Proceedings of the National Seminar : 23 Nov 20 0 › pdf › APAB SOUVENIR 2010.pdf · the like; the science or art of designing and accelerating projectiles so as to achieve a desired

P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | �

Proceedings of the National Seminar : 23 Nov 20�0

2 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa


P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 3


SOUVENIR

PROcEEdINgS Of thE NatIONal SEmINaR ON

REcENt tRENdS IN BallIStIcS aNd matERIal ScIENcE( November 23 , 20�0 )

Organised byP. G. DePartment of aPPlieD Physics anD Ballistics

Fakir Mohan University Vyasa Vihar , South Campus, Balasore-7560�9 , Orissa

Website: www.fmuniversity.nic.in

� | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa


Editorial Board :Editor-in-Chief : Flt Lt Dr Munesh Chandra AdhikaryEditors : Prof Govinda Chandra Rout Dr Sidhartha Pattanaik Dr Santosh Kumar Agarwalla Er Ashanta Ranjan Routray











About the Department

The Department of Applied Physics and Ballistics was established

in the year 2007 as a regular Post Graduate Department of Fakir Mohan

University, Balasore, Orissa. This Department offers the course like M.Sc

in Applied Physics and Ballistics having a strength of �6 with two Special

Papers like Ballistics and Electronics.. The uniqueness of the Department

is that it is the first and only Post Graduate Department under a

general State University , all over the country, introducing a course like

Ballistics with a vision to fulfill the requirement of defence research and

development services.

The vision of this department is to become a center of excellence

in education and research in the field of Applied Physics and Ballistics.

And its mission is to achieve success in University examinations, National

level competetive examinations like NET, GATE,JEST, SLET etc and also

in the qualifying examinations of DRDO , UPSC and othe research

institutes.

The syllabus of M.Sc. course has been framed based on the latest

UGC curriculum as well as various national level tests like NET, GATE etc.

In addition to the general topics of Physics , it includes most innovative

topics like Internal Ballistics, External Ballistics, Terminal Ballistics, Weapon

Systems, Ballistics Instruments, Rocket Ballistics, Modelling & Simulations,

Fluid Dynamics and Material Science etc. It provides the Special Paper

like Ballistics and Electronics. The Department is fortunate to have a team

�0 | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa


of well trained, young and dynamic teaching staffs having determination to impart quality teaching.

Apart from the lecture time, interaction with students is the top priority of all the staff members. The

specialized topics are covered by the reputed scientists of Proof and Experimental Establishments ( PXE

) and Integrated Test Range ( ITR ) , Chandipur.

The Department motivates the students to persue research career and at present it gives the

opportunity for doctoral degree in the emerging fields like Condensed Matter Physics, Material Science

( Nanotechnology) , Nuclear Physics, Ballistics and Computer Science. The experimental facilities for

the M.Sc. students are provided by its various labs like Computational Physics Lab, Modern Physics Lab,

Material Science and Ballistics Lab and Electronics Lab. For advance researches, a new Advanced Research

Laboratory is set up having the imported equipments like Scanning Electron Microscope ( SEM ) with

EDX , Fourier Transform Infra Red ( FTIR ) with TGA-�000 and others Universal Testing Machine ( UTM ) ,

Internal Mixer, Hot Air Oven, Hydraulic Press etc. Future vision is there to procure X-Ray Diffractometer (

XRD ), Impedance Analyser, Atomic Force Microscope ( AFM ) , LASER etc.

As the heighlights of Department , it provides a number of facilities to the students like

internet access through wireless LAN, Seminar library books, reading room , Class rooms provided with

audio-visual systems, LCD Projectors, Computers etc. The departmental seminars have been conducted

regularly involving the students , teachers and invited speakers from outside renouned research

institutes, universities , DRDO labs and even from abroad. The students are sent to DRDO Labs like PXE

and ITR, Chandipur for their Project works as requirement of University examination. Besides, number

of students are sent each year for undergoing Summer Training Courses at different renouned research

institutes of India like Variable Electron Cyclotron Centre( VECC ), Kolkata ; Institute of Plasma Research (

IPR ) , Ahamadabad ; Physical Research Laboratory ( PRL) , Ahamadabad; Bose Institute of Basic Sciences,

Kolkata ; Institute of Physics ( IOP ), Bhubaneswar etc. Further all the students as per requirement, are

exposed to workshops & Continuing Education Programme( CEP ) conducted at PXE, Chandipur. Above

all, our students are given free coaching for the preparation of various competitive examination like NET,

GATE, JEST, SLET etc. on Sundays and holidays by the internal as well as external faculties.

So finally this Department keeps the vision of Fakir Mohan University to excel in five ethoses :

• The Culture of Excellence

• The Culture of Innovation

• The Culture of Quality

• The Culture of Flexibility and Dynamism

• The Culture of Sustainability

**********************

P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | �


RECENT TRENDS IN BALLISTICS AND MATERIAL SCIENCE

V. Anguswamy

Scientist-F, Associate Director, PXE, DRDO, Chandipur

introDUction

Ballistics is the science of mechanics that deals

with the flight, behaviour, and effects of projectiles,

especially bullets, gravity bombs, rockets, or

the like; the science or art of designing and

accelerating projectiles so as to achieve a desired

performance.

The field of ballistics can be broadly

classified into three major disciplines: interior

ballistics, exterior ballistics, and terminal ballistics.

In some instances, a fourth category named

intermediate ballistics has been used.

Interior ballistics deals with the

interaction of the gun, projectile, and propelling

charge before emergency of the projectile from

the muzzle of the gun. This category would include

the ignition process of the propellant, the burning

of propellant in the chamber, pressurization of the

chamber, the first-motion event of the projectile,

engraving of any rotating band and obturation

of the chamber, in-bore dynamic of the projectile,

and tube dynamics during the firing cycle.

internal Ballistic

A ballistic body is a body which is free to move,

behave, and be modified in appearance, contour,

or texture by ambient conditions, substances, or

forces, as by the pressure of gases in a gun, by

rifling in a barrel, by gravity, by temperature, or

by air particles. A ballistic missile is a missile only

governed by the laws of classical mechanics.

ProPellant charGe

(Load density and consistency)

Load density is percentage of the space

in the cartridge of the3 space in the cartridge case

that is filled with powder. In general, loads close

to �00% density (or even loads where seating the

bullet in the case, compresses the poser) ignite and

burn more consistently than lower-density loads.

In cartridges surviving from the black-powder era,

the case is much larger than is needed to hold

the maximum charge of high-density smokeless

powder. This extra room allows the power to shift

in the case, piling up near the front or back of the

case and potentially causing significant variations

in burning rate, as powder near the rear of the

case will ignite rapidly but powder near the front

of the case will ignite later. This charge has less

impact with fast powders. Such high-capacity, low-

Invited Paper



density cartridges generally deliver best accuracy

with the fastest appropriate powder, although this

keeps the total energy low due to the sharp high-

pressure peak.

Peak vs area

Energy is defined as a force exerted over a

distance; for example, the work required to lift

a one-pound weight, one foot against the pull

of gravity defines a foot- pound of energy (One

joule is equal to energy used to move a body

over a distance of one meter using one Newton

of force). If we were to modify the graph to reflect

pressure as a function of distance, the area under

that curve would be the total energy imparted to

the bullet. From this, it can be seen that the way to

increase the energy of the bullet is to increase the

are under that curve, either by raising the average

pressure, or increasing the distance, the bullet

travels under pressure (in other words, lengthen

the barrel).

Propellant burnout

Another issue to consider, when choosing a

powder burn rate, is the time the powder takes

to completely burn vs. the time the bullet spends

in the barrel. Since the burn rate of nitrocellulose-

based powders increases with increasing pressure,

this can be a very difficult interaction to guess,

and requires careful testing with gradual changes.

Looking carefully at the left graph, there is a

change in the curve, at about 0.� ms. This is the

point at which the powder is completely burned,

and no new gas is created. With a faster powder,

burnout occurs earlier, and with the slower

powder, it occurs later. Propellant that is unburned

when the bullet reaches the muzzle is wasted — it

adds no energy to the bullet, but it does add to

the recoil and muzzle blast. For maximum power,

the powder should burn until the bullet is just

short of the muzzle.

Since smokeless powders burn, not

detonate, the reaction can only take place on the

surface of the powder. Smokeless powders come

in a variety of shapes, which serve to determine

how fast they burn, and also how the burn rate

changes as the powder burns. The simplest shape

is a ball powder, which is in the form of round

or slightly flattened spheres. Ball powder has a

comparatively small surface-area-to-volume ratio,

so it burns comparatively slowly, and as it burns, its

surface area decreases. This means as the powder

burns, the burn rate slows down.

To some degree, this can be offset by

the use of a retardant coating on the surface of

the powder, which slows the initial burn rate and

flattens out the rate of change. Ball powders are

generally formulated as slow pistol powders, or

fast rifle powders.

This is a graph of a simulation of the 5.56 mm NATO

round, being fired from a 20-inch (510 mm) barrel.

The horizontal axis represents time, the vertical axis

represents pressure (green line), bullet travel (red

line), and bullet velocity (light blue line). The values

shown at top are peak values



Flake powders are in the form of flat, round flakes

which have a relatively high surface-area-to-

volume ratio. Flake powders have a nearly constant

rate of burn, and are usually formulated as fast

pistol or shotgun powders. The last common

shape is an extruded powder, which is in the form

of a cylinder, sometimes hollow. Extruded powders

generally have a lower ratio of nitroglycerin to

nitrocellulose, and are often progressive burning

— that is, they burn at a faster rate as they burn.

Extruded powders are generally medium to slow

rifle powders.

eXternal Ballistics

Just two key factors determine the external

ballistics of a projectile; the muzzle velocity

and the ballistic coefficient. The ballistic

coefficient is significant because it determines

the rate at which the projectile slows down, and in

conjunction with the muzzle velocity this decides

the maximum range (at any given elevation) and

the time of flight to any particular distance. The

time of flight in turn decides the amount by which

the projectile drops downwards as this happens

at a constant rate due to gravity. The curved path

of the projectile which results from the muzzle

velocity, the ballistic coefficient and gravity drop

is called the trajectory.

In most types of long-range shooting

(whether by rifles or large cannon) a short time of

flight is considered desirable because it maximizes

the hit probability by reducing the time of flight

and flattening the trajectory. It also results in the

projectile striking the target at a high velocity and

therefore with greater effect. The main exception

is when artillery fires in the “upper register” (above

�5 degrees elevation) to achieve plunging fire.

The advantages of a high muzzle velocity

in reducing the time of flight are self-evident. So

are the disadvantages: more propellant is required,

the barrel will need to be longer, the gun will be

This graph shows different pressure curves for powders with different burn rates. The leftmost graph is the

same as the large graph above. The middle graph shows a powder with a 25% faster burn rate, and the

rightmost graph shows a powder with a 20% slower burn rate.



heavier and (in the case of a mounted weapon)

so will be the mounting to cope with the greater

recoil. In an automatic weapon, the rate of fire is

also usually lower. As we have seen, there is also

a practical limit to how high the velocity of any

given projectile can be pushed. To make the most

of the muzzle velocity, we need to achieve a high

ballistic coefficient.

There are two elements which decide the

ballistic coefficient (Bc); the sectional density

(sD) and the form factor (ff). The SD is a simple

calculation as it is the ratio between calibre and

projectile weight. The formula is:

For metric measurements: multiply

the projectile weight in grams by �.�22, then

divide the result by the square of the calibre in

millimetres. So for a �2.7mm bullet weighing �0

grams: (�0x�.�22)/(�2.7x�2.7) = an SD of 0.353

For Imperial measurements: divide the

projectile weight in pounds by the square of the

calibre in inches (if bullet weights are in grains,

divide the result by 7,000).

The higher the SD figure, the better the

velocity retention (assuming equal form factors).

What the SD measures is the weight (or

momentum, when moving) behind every square

millimetre of the projectile calibre (i.e. the cross-

sectional area of the projectile). If projectiles were

solid cylinders then for a given SD figure they would

all be the same length regardless of their calibre. In

practice, of course, the length varies with the calibre;

a �0mm projectile will be about twice the length of

a 20mm, and will therefore have about double the

SD figure. This explains why artillery shells travel

much further than rifle bullets, no matter how fast

or streamlined. Other things being equal, the bigger

the calibre, the longer the range and the shorter the

flight time to any given range.

The first problem is that the FF is different

at subsonic and supersonic velocities, because

shapes which work best at subsonic speeds are

not the best at supersonic velocities. At subsonic

speeds, the drag caused by the low-pressure area

created at the back or base of the projectile is

significant, and major reductions in drag can be

made by tapering this to some extent (streamlining

or boat-tailing). At supersonic speeds, it is the

nose shape that is critical; finely pointed noses

are needed, but the back end doesn’t matter so

much. Some taper towards the base is useful, but

the optimum taper angle is different from that at

subsonic velocities. The benefit of boat-tailing at

very long range can be demonstrated by two .30-

06 bullets, both weighing ��0 grains (��.7g) and

fired at 2,700 fps (�23 m/s). At sea level, the flat-

based bullet will travel a maximum of 3,�00m, the

boat-tail 5,200m.

A further factor affecting military

projectiles is the addition of tracer elements.

These generate gas which helps to fill the low-

pressure area at the base, reducing drag. This gives

them a different trajectory by comparison with

non-tracer rounds, not helped by the fact that as

the tracer burns up the weight of the projectile

reduces, thereby worsening its sectional density.

Tracers can therefore never achieve a perfect

match with other projectiles and can only ever be

an approximate guide to their trajectory.

Putting all of this together, the most

aerodynamically sophisticated projectiles in use

today are the long-range artillery shells known as

erfBBB (extended-range full-bore base-bleed).

These have a long, finely pointed nose to work well

at their initial supersonic speeds, and a tapered

base filled with a “base bleed” burning chemical

which essentially does the same aerodynamic job



as a tracer. Furthermore, the nose is so pointed

that only the base of the shell is in contact with

the barrel, so small streamlined stubs are fitted

part way up the shell to keep it centred in the

bore. It was discovered that these generate some

aerodynamic lift, like tiny wings, and extend the

range still further. The advantage of all of this

can be seen in the range improvement over a

conventional �55mm HE shell; in a 39 calibre barrel,

the standard M�07 shell has a range of ��,�00m,

the ERFB shell 25,500m and the ERFBBB 32,�00m.

Furthermore, unlike rocket-assisted or sub-calibre

shells, there is no penalty in effectiveness as they

carry at least as much HE (in fact, the South African

�55mm M57 ERFB shell contains 30% more HE

than the standard M�07 shell).

terminal Ballistics

There are two different aspects to this; the effect

of projectile strike against soft targets (animals or

people) and the effect against armour. The former

is described in more detail here.

First, against soft targets (the squeamish

have permission to duck this section!). A military

(i.e. fully jacketed, pointed, non-expanding) rifle

bullet will be destabilised when hitting a soft

target and will tumble. This is because its shape

means that the centre of gravity of the bullet

is towards the rear so it naturally prefers to fly

base-first. Spinning the bullet by means of the

rifling keeps the bullet flying point-first through

the air, but flesh is about �00 times denser than

air so spinning is no longer enough; the bullet

destabilises and turns over to travel base-first,

a process known as tumbling. In so doing it

obviously inflicts a far more serious wound than

if it carried on flying straight through the body.

Incidentally, bullets designed for penetrating

heavy game animals like elephant - which need to

penetrate very deeply in a straight line and must

therefore not yaw or tumble - have long, parallel

sides and blunt round noses, just like early military

rifle bullets.

Not all bullets tumble at the same rate.

Other things being equal, small bullets will tumble

more quickly than large ones, but the design of

the bullet is also important; some visually identical

bullets will tumble at different speeds, generally

depending on the internal construction. For

example, the Yugoslavian bullet for the 7.62x39

has a lead core and has been found in tests to

tumble much more quickly than the Russian steel-

cored bullet in the same cartridge. Various tricks

have been used to increase the probability of a

bullet tumbling; the British .303 Mk VII bullet had a

lightweight tip filler with the weight concentrated

towards the rear of the bullet, and the current

Russian 5.�5mm rifle bullet has a hollow tip.

If a bullet has a relatively weak jacket, the

stresses of tumbling may cause it to break apart

while it is travelling sideways through flesh - a

process known as fragmentation - which further

increases the wounding effect. Most 5.56x�5

military bullets fragment, although they have to

be travelling at high velocity to do so. This limits

their maximum effectiveness to fairly short range,

particularly from short-barrelled carbines which

have a lower muzzle velocity. Most 7.62x5� NATO

bullets do not fragment, although the German

one does - by accident rather than design.

Fragmentation is not an official requirement for

any military bullets; if it were, there might be some

legal challenge over the international prohibition

on bullets designed to cause unnecessary

suffering. The noses of hunting rifle bullets (and



many commercial handgun bullets) are designed

to expand on impact, which greatly increases the

size of the wound channel. Such bullets are illegal

for military use.

It is often claimed by hunters that as the

striking velocity of the bullet increases beyond

about 700 m/s (2,300 fps), so hydrostatic shock

begins to appear, with the effect that animals drop

dead much more dramatically than if hit in the

same place with a low-velocity bullet. However, this

effect does not seem to be replicated in people;

there are many cases of soldiers continuing to

fight for some time despite receiving severe (and

ultimately fatal) wounds from high-velocity rifle

bullets. Furthermore, serious shock effects are

only likely if the bullet exceeds the speed of sound

in flesh, which is around �,500 m/s (�,900 fps), but

even this has been disputed.

This brings us onto the vexed question of

stopping power, about which it is impossible to

make any pronouncements without stimulating

fierce arguments. Stopping power may be defined

as the ability of a particular weapon to immediately

disable an opponent so he can take no further

part in the fighting. It is not the same as lethality;

quite low-powered weapons can be lethal, but

considerably more power is normally required to

achieve reliable stopping power. Incidentally, this

shows that the notion that modern military rifle

bullets are meant to wound rather than kill is a

myth; if it is powerful enough to disable, it is more

than powerful enough to kill.

Materials

Various materials are use in mechanical devices,

components, & systems; these materials are

selected & applied based on their merits. It is

required above all that they conform to all of the

design specifications & requirements. They must

either be readily available in the specified final

form, or they must be capable of being made and

processed with minimum effort, be repairable,

and serviceable during use. They should also be

economical in general.

metallic materials are the prime

materials of choice, and steels of all kinds get the

first pick. In addition, copper alloys, such as brasses

and bronzes, are widely used due to their excellent

thermal conduction characteristics. Among the

light metals, aluminum alloys and titanium alloys

find widespread applications. Superalloys based

on nickel or cobalt or iron are widely sought after.

Although several other metallic materials do find

some applications in Armament systems.

Ceramic Materials

Ceramics are used in Armament applications

because of their inertness, hardness, were and

corrosion resistances, and insulation traits. They

are also able to withstand fairly high temperatures

without any deterioration. Ceramics are light and

creep resistant generally. They are inherently

brittle. Important ceramics are : oxides, nitrides

and silicates. carbides are also considered as

ceramics.

Plastics and Polymeric Materials

Polymers are giant organic molecules synthesized

from smaller compounds. They are essentially

based on group � non-transition elements.

They are of two varieties : one based on carbon

and the other on silicon ( the silicones). Because

combinations of both of these elements in



organic molecules is possible, there are polymeric

compounds containing both carbon and silicon.

Composites are generally three-

dimensional, man-made materials that contains

two or more distinct component material types,

such as metals, ceramics, and polymers, or phases

with vastly different properties, such as Kevlar

fibers strengthening nylon; these are unified to

develop the best of both types, that is, to extract

unique and optimum properties that are not

available otherwise. A unique interface exists

among the component entities, the matrix, and

the strengthening agent. Indeed this is the cause

for some of the weakness encountered in some

composites.

Under the man- made category of

composites, five important classes can be identified

based on the component materials present. In all

of these composites, there is a continuous matrix

into which a second-phase or different material

kind is embedded. The matrix material or phase

should also be dominate, meaning it should

occupy the bulk of the volume. The five classes

of composites are : polymer-matrix composites

(PMCs), metal-matrix composites (MMCs), ceramic-

matrix composites (CMCs), bio-matrix composites

(BMCs), and similar material composites (SMCs).

Within these classes, the composites are also sub-

divided as fiber-reinforced, particle-reinforced

or dispersion strengthened, and laminate types;

these sub-divisions depend on the morphological

features of the strengthening second material or

phase component.

conclUsion

Conventional Armaments continues to play a

decisive role even in the present scenario of

nuclear weapons and electronic warfare. As a war

fighting technology, they are low cost, reliable,

highly effective and proven in several battle

field situations. Application of advancements

in electronics, materials and manufacturing

technologies, computers and propulsion

technologies has added new dimensions to

armament technology.

reference

[�] Donald E. Carlucci and Sidney S. Jacobson -“Ballisitcs” Theory and Design of Gun and ammunition

[2] GM Moss, , D W Leeming & C L Farrar -“ Military Ballistics”

[3] A Raman-“Materials selection and application in Mechanical Engineering”

[�] Ludwing Stiefel - “Gun Propulsion Technology”

[5] Jaiprakash Agrawal -“High energy Materials”

[6] Richard M Lloyd -“Conventional Warhead systems

Physics And Engineering Design



MULTI-TARGET TRACKING IN A TEST RANGE SCENARIO

R Appavu Raj

Sc ‘G’, Additional Director, Integrated Test Range, Chandipur

Abstract

Integrated Test Range (ITR) handles various types of multiple target flight trials.

To facilitate target tracking and estimation in such multi-target scenario, nearest

neighbourhood (NN) technique based data association algorithm has been adopted

at ITR. The present paper discusses the NN-based data association algorithm and its

performance in a real flight trial situation by using multiple-target track data from a

multi-target tracking radar.

1. introDUction

Integrated Test Range (ITR), Chandipur handles

test and evaluation of short, medium and long

range guided missiles, rockets and various other

air-borne objects. Ensuring safety of life and

properties in and around the launch corridor

is indispensable requirement during test and

evaluation of these developmental flight vehicles.

This necessitates real time monitoring of the flight

vehicle’s trajectory and health status with that of

the desired one. This in turn is possible with the use

of an efficient tracking and estimation algorithm

which extracts useful information from multiple

tracking sensor’s noisy measurement data for the

purpose of real time flight safety monitoring as

well as for post-flight performance analysis.

The different flight scenarios encountered

at ITR are engagement of multiple targets by

multiple missiles, ejection of multiple payloads,

engagement of air to air missiles, etc. In view of

this, the target tracking and estimation algorithm

should be capable of detecting and tracking

different targets by utilizing the measurements

from various sensors. In a multi-target tracking

situation, a single sensor or a number of sensors

can observe multiple targets at a time. Assessment

of the actual scenario in such situations becomes

complicated due to increased level of uncertainties

as opposed to single target tracking. In addition to

the presence of measurement noise of unknown

or partially known statistical properties, the source

responsible for each measurement is unknown in

this case. The situation gets further complex in

presence of false alarm & clutter and when the

number of targets is also unknown. In a dense

target scenario, it is very difficult to associate a

measurement with its source (even when each of

the targets is resolved by the sensors) with certainty.

On the other hand, the inherent limitations of the

tracking sensors may fail to resolve closely spaced

targets and thus inhibit appropriate assessment

of target scenario. Hence, the central problem

in multi-target tracking is data association, i.e.,

identifying the target responsible for individual

measurement. Further, the algorithm must have

efficient methodology for track initiation and

track deletion.

Commonly used association techniques

are distance measure, association coefficient,

correlation coefficient, probabilistic similarity

measures etc. [�]. Based on these techniques,

there are a number of algorithms for tracking

in multiple target environment [2], e.g. track

splitting approach, nearest neighbourhood

method, maximum likelihood method, Bayesian

approach etc. In track-splitting approach, a track

is split, whenever more than one detection

is observed in the neighbourhood of the

predicted measurement. The likelihood function

of each trajectory is computed and the track is

dropped when the likelihood value is less than a

predetermined threshold. Although this method

is suitable for track initiation and update, memory

and computational requirements become very

high in a dense target environment. For simplicity

as well as efficiency of the algorithm, Nearest

Neighbourhood based data association algorithm

has gained popularity. It is accomplished by

defining a measure of association that quantifies

the closeness between measurement pairs or

measurement to track pairs. There are some

difficulties in performing multi sensor tracking

due to uncertain data and disparate data

sources. The identity of the targets responsible

for each individual data set is unknown, so there

is uncertainty as how to associate data from

one sensor which are obtained at one time and

location to those of another sensor at another

point in time and location. Tracking is further

complicated by the fact that some sensors may

not observe the targets due to the variation of

signals and the sensor characteristics. Also, false

alarms and the clutter may be present which are

not easily distinguishable from the true target

measurements.

Gating and data association enable

tracking in multi sensor multi target scenario.

Gating helps in deciding if an observation (which

includes clutter, false alarms and electronic counter

measures) is a probable candidate for track

maintenance or track update and Data association

is the step to associate the measurements to the

targets with certainty when several targets are in

the same neighborhood.

2. Basic comPonents of raDar

The schematic diagram of radar in Fig. 2.� shows

its fundamental components. A transmitter

generates the radio signal with an oscillator such as

a klystron or a magnetron and controls its duration

by a modulator. A waveguide links the transmitter

and the antenna. The duplexer serves as a switch

between the antenna and the transmitter or the

receiver for the signal when the antenna is used in

both situations. Knowing the shape of the desired

received signal (a pulse), an optimal receiver can

Invited Paper



MULTI-TARGET TRACKING IN A TEST RANGE SCENARIO

R Appavu Raj

Sc ‘G’, Additional Director, Integrated Test Range, Chandipur

Abstract

Integrated Test Range (ITR) handles various types of multiple target flight trials.

To facilitate target tracking and estimation in such multi-target scenario, nearest

neighbourhood (NN) technique based data association algorithm has been adopted

at ITR. The present paper discusses the NN-based data association algorithm and its

performance in a real flight trial situation by using multiple-target track data from a

multi-target tracking radar.

1. introDUction

Integrated Test Range (ITR), Chandipur handles

test and evaluation of short, medium and long

range guided missiles, rockets and various other

air-borne objects. Ensuring safety of life and

properties in and around the launch corridor

is indispensable requirement during test and

evaluation of these developmental flight vehicles.

This necessitates real time monitoring of the flight

vehicle’s trajectory and health status with that of

the desired one. This in turn is possible with the use

of an efficient tracking and estimation algorithm

which extracts useful information from multiple

tracking sensor’s noisy measurement data for the

purpose of real time flight safety monitoring as

well as for post-flight performance analysis.

The different flight scenarios encountered

at ITR are engagement of multiple targets by

multiple missiles, ejection of multiple payloads,

engagement of air to air missiles, etc. In view of

this, the target tracking and estimation algorithm

should be capable of detecting and tracking

different targets by utilizing the measurements

from various sensors. In a multi-target tracking

situation, a single sensor or a number of sensors

can observe multiple targets at a time. Assessment

of the actual scenario in such situations becomes

complicated due to increased level of uncertainties

as opposed to single target tracking. In addition to

the presence of measurement noise of unknown

or partially known statistical properties, the source

responsible for each measurement is unknown in

this case. The situation gets further complex in

presence of false alarm & clutter and when the

number of targets is also unknown. In a dense

target scenario, it is very difficult to associate a

measurement with its source (even when each of

the targets is resolved by the sensors) with certainty.

On the other hand, the inherent limitations of the

tracking sensors may fail to resolve closely spaced

targets and thus inhibit appropriate assessment

of target scenario. Hence, the central problem

in multi-target tracking is data association, i.e.,

identifying the target responsible for individual

measurement. Further, the algorithm must have

efficient methodology for track initiation and

track deletion.

Commonly used association techniques

are distance measure, association coefficient,

correlation coefficient, probabilistic similarity

measures etc. [�]. Based on these techniques,

there are a number of algorithms for tracking

in multiple target environment [2], e.g. track

splitting approach, nearest neighbourhood

method, maximum likelihood method, Bayesian

approach etc. In track-splitting approach, a track

is split, whenever more than one detection

is observed in the neighbourhood of the

predicted measurement. The likelihood function

of each trajectory is computed and the track is

dropped when the likelihood value is less than a

predetermined threshold. Although this method

is suitable for track initiation and update, memory

and computational requirements become very

high in a dense target environment. For simplicity

as well as efficiency of the algorithm, Nearest

Neighbourhood based data association algorithm

has gained popularity. It is accomplished by

defining a measure of association that quantifies

the closeness between measurement pairs or

measurement to track pairs. There are some

difficulties in performing multi sensor tracking

due to uncertain data and disparate data

sources. The identity of the targets responsible

for each individual data set is unknown, so there

is uncertainty as how to associate data from

one sensor which are obtained at one time and

location to those of another sensor at another

point in time and location. Tracking is further

complicated by the fact that some sensors may

not observe the targets due to the variation of

signals and the sensor characteristics. Also, false

alarms and the clutter may be present which are

not easily distinguishable from the true target

measurements.

Gating and data association enable

tracking in multi sensor multi target scenario.

Gating helps in deciding if an observation (which

includes clutter, false alarms and electronic counter

measures) is a probable candidate for track

maintenance or track update and Data association

is the step to associate the measurements to the

targets with certainty when several targets are in

the same neighborhood.

2. Basic comPonents of raDar

The schematic diagram of radar in Fig. 2.� shows

its fundamental components. A transmitter

generates the radio signal with an oscillator such as

a klystron or a magnetron and controls its duration

by a modulator. A waveguide links the transmitter

and the antenna. The duplexer serves as a switch

between the antenna and the transmitter or the

receiver for the signal when the antenna is used in

both situations. Knowing the shape of the desired

received signal (a pulse), an optimal receiver can

Invited Paper



be designed using a matched filter. Finally, the

electronic section controls all those devices and

the antenna to perform the radar scan ordered by

a software [�, 5].

3.2 Gating

This step aims at finding possible measurement

to target pairings based on the likelihood of the

predicted target position and the measurement

based on Chi-square threshold. This makes use of

state prediction covariance, innovation covariance

obtained from Kalman filter. This defines the

gate G such that the correlation is allowed if the

following relationship is satisfied:

d2 = yk S

k-�y

kT ≤ G

where, d2 = norm of measurement residual

yk = measurement residual at k-th instant

= Zk - Hx

k|k-�

Zk = actual measurement at k-th instant

xk|k -�

= predicted state at k-th instant

H = measurement matrix

S = covariance matrix of measurement residual

= HPk|k-�

HT + R

Pk|k =�

= estimation error of predicted state at k-th

instant

R = covariance matrix of measurement error

Assuming the components of measurements

(i.e. measurement in x, y and z-direction) to

be independent and measurement noise and

process noise to be zero mean and Gaussian and

independent of each other, yk becomes zero mean

and Gaussian. Hence, d2 (as defined above) being

Fig. 2. �: Radar System Schematics [�]

3. alGorithm aDoPteD at itr

Nearest Neighbourhood (NN) technique (based

on distance measure) for data association

has been adopted at ITR for the purpose of

identifying measurement-to-target pairs [�, 3].

Nearest Neighbourhood (NN) technique aims

at providing target information by resolving

targetmeasurement pairings in a multi-target

multi sensor scenario. This algorithm is based

on likelihood theory and the goal is to minimise

an overall distance function that considers

all observation to track pairings that satisfy a

preliminary gating test. As the number of targets

are not known a priori, track-oriented approach is

adopted for the present application. The different

steps of NN algorithm adopted at ITR are shown in

Fig. 3.� and are discussed below.

3.1 Data Alignment

Measurements from different sensors are available

in different sensor-specific coordinate frame, in

different data rate and w.r.t. respective sensor

locations. These data are converted into a uniform

temporal and spatial reference.

∼

∼

∼

sum of square of M (number of components of

measurements=3 in present case) independent

zero-mean unity variance Gaussian random

variable, is a random variable with Chi-Square

distribution. Assuming allowable probability of

valid observation falling outside the gate G, the

value of G can be determined by Chi-Square table

and the following relation:

Probab [ χM

2 > G ] = �- PG ,

where, PG = probability of valid observation falling

within the gate. Hence, for a particular M, the size

of gate is decided by PG and the performance of

the NN algorithm is affected by the value of PG .

3.3 Correlation

This is the process to update target

information based on the associated

measurements to the target in a situation

where either one measurement satisfies the

gate of more than one target [�], or more than

one measurement satisfies the gate of one

target, or no measurement fulfils the gating

criteria of a particular target. The process of

correlation is executed in NN by minimising


all measurement to track pairings that satisfy

the preliminary gating test. This way only one

measurement is used at each scan to update

information pertaining to a particular target

(in contrary to all measurements satisfying

the gate as in Probabilistic Data Association

technique [�]).

3.4 Track Update, Track Initiation

Based on the results of correlation, each of the

existing tracks is updated with the correlated

measurement. If there is any measurement

which does not satisfy gating test of any of the

existing tracks, the measurement is assumed to

be generated by a new target. Hence, a new track

is initiated based on that measurement. If there is

some existing tracks, which do not have any valid

measurements associated with them, the track

is predicted for the next time interval (without

measurement update).

Fig. 3.� : Block diagram for data association In

multi-sensor-multi-target scenario

P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | ��


be designed using a matched filter. Finally, the

electronic section controls all those devices and

the antenna to perform the radar scan ordered by

a software [�, 5].

3.2 Gating

This step aims at finding possible measurement

to target pairings based on the likelihood of the

predicted target position and the measurement

based on Chi-square threshold. This makes use of

state prediction covariance, innovation covariance

obtained from Kalman filter. This defines the

gate G such that the correlation is allowed if the

following relationship is satisfied:

d2 = yk S

k-�y

kT ≤ G

where, d2 = norm of measurement residual

yk = measurement residual at k-th instant

= Zk - Hx

k|k-�

Zk = actual measurement at k-th instant

xk|k -�

= predicted state at k-th instant

H = measurement matrix

S = covariance matrix of measurement residual

= HPk|k-�

HT + R

Pk|k =�

= estimation error of predicted state at k-th

instant

R = covariance matrix of measurement error

Assuming the components of measurements

(i.e. measurement in x, y and z-direction) to

be independent and measurement noise and

process noise to be zero mean and Gaussian and

independent of each other, yk becomes zero mean

and Gaussian. Hence, d2 (as defined above) being

Fig. 2. �: Radar System Schematics [�]

3. alGorithm aDoPteD at itr

Nearest Neighbourhood (NN) technique (based

on distance measure) for data association

has been adopted at ITR for the purpose of

identifying measurement-to-target pairs [�, 3].

Nearest Neighbourhood (NN) technique aims

at providing target information by resolving

targetmeasurement pairings in a multi-target

multi sensor scenario. This algorithm is based

on likelihood theory and the goal is to minimise


all observation to track pairings that satisfy a

preliminary gating test. As the number of targets

are not known a priori, track-oriented approach is

adopted for the present application. The different

steps of NN algorithm adopted at ITR are shown in

Fig. 3.� and are discussed below.

3.1 Data Alignment

Measurements from different sensors are available

in different sensor-specific coordinate frame, in

different data rate and w.r.t. respective sensor

locations. These data are converted into a uniform

temporal and spatial reference.

∼

∼

∼

sum of square of M (number of components of

measurements=3 in present case) independent

zero-mean unity variance Gaussian random

variable, is a random variable with Chi-Square

distribution. Assuming allowable probability of

valid observation falling outside the gate G, the

value of G can be determined by Chi-Square table

and the following relation:

Probab [ χM

2 > G ] = �- PG ,

where, PG = probability of valid observation falling

within the gate. Hence, for a particular M, the size

of gate is decided by PG and the performance of

the NN algorithm is affected by the value of PG .

3.3 Correlation

This is the process to update target

information based on the associated

measurements to the target in a situation

where either one measurement satisfies the

gate of more than one target [�], or more than

one measurement satisfies the gate of one

target, or no measurement fulfils the gating

criteria of a particular target. The process of

correlation is executed in NN by minimising


all measurement to track pairings that satisfy

the preliminary gating test. This way only one

measurement is used at each scan to update

information pertaining to a particular target

(in contrary to all measurements satisfying

the gate as in Probabilistic Data Association

technique [�]).

3.4 Track Update, Track Initiation

Based on the results of correlation, each of the

existing tracks is updated with the correlated

measurement. If there is any measurement

which does not satisfy gating test of any of the

existing tracks, the measurement is assumed to

be generated by a new target. Hence, a new track

is initiated based on that measurement. If there is

some existing tracks, which do not have any valid

measurements associated with them, the track

is predicted for the next time interval (without

measurement update).

Fig. 3.� : Block diagram for data association In

multi-sensor-multi-target scenario



4. nUmerical simUlation anD resUlts

The relevance of NN algorithm to a typical

Test Range scenario like ITR can be established

by testing and evaluating the algorithm for

different possible multi-target scenario. This is

accomplished by testing the algorithm by using

data from a multiple target tracking radar. Here,

the number of target tracked by the radar varies

at different instant of time. The algorithm does not

assume the maximum number of target tracked

by the sensor. In turn it identifies the number of

valid target within the field of view of the sensor

and estimates state of the targets by using the

noisy measurement from the sensor. Apart from

the nearest neighbourhood data association

algorithm, the algorithm uses a Kalman filter for

estimating the target state. The estimator uses

second order kinematics in Cartesian coordinates

for the target model.

The values assumed for the different

design parameters of Nearest Neighbourhood

algorithm are as given in Table 3.�. With these

parameter values the algorithm has been tested

for two different process noise levels as mentioned

above.

The track results of the algorithm for noise

standard deviation of 5-m, 50m and 5 m in x, y &

z directions respectively are shown in fig. �.�(a)-

�.�(c) and for noise standard deviation of 5m, 50m

and �0 m in x, y & z directions respectively are

shown in fig. �.2(a)-�.2(c).

It is seen from the track data of the Multi-

Target Tracking (MTT) radar that the elevation

measurement is very noisy and that has been

reflected in noisy altitude measurement data.

Although the estimation results in x and y position

is satisfactorily, the noisy altitude measurement

results in poor performance of altitude estimation.

Moreover, the noise standard deviation for the

sensor plays a major role in gating performance

(by computing the volume around the existing

track within which the measurement in the future

scans is likely to be). Fig �.2 brings out that the

larger noise standard deviation assumed in this

case results in a erroneous association result at

one instant (apparent from the track switching

between two targets near sample no. 790.

Table �.�

Distance threshold �00m

Redundant Threshold �00m

Prune Threshold 0

Chi Square Threshold 25

No. of Samples �000

Kalman Filter model for

target state estimation

Process noise standard

deviation

Measurement noise

standard deviation

Constant velocity

model with additive

white Gaussian noised

in acceleration

�0 m2/sec� and

�00 m2/sec� in two

different cases of the

study

5 m in x direction, 50m

in y direction and 5 &

�0m in z direction

5. conclUDinG remarKs

The nearest neighbourhood based data

association and target tracking algorithm has

been presented in this paper and the performance

of the algorithm has been established by using

multiple target tack data from a radar. The results

show that by judicious choice of error variances,

the algorithm performs satisfactorily to

estimate the kinematic state of all the targets

during the flight trials of multiple targets. Since

the algorithm utilizes track oriented approach,

the information regarding the number of

targets present in the scenario is not required

for execution of the algorithm. Exhaustive

sensitivity studies have been carried out for

the adopted algorithm and the results show

that the algorithm can perform unambiguously

even in the presence of false alarm and for very

closely spaced targets.

references

[�] S S Blackman, Multiple target tracking with radar applications, Artech House Inc., Norwood.

[2] Y Bar-Shalom, ‘Tracking methods in a multi-target environment’, IEEE Transaction on Automatic Control, Vol. AC-23, No. �, August, �97�.

[3] Shrabani, R Appavu Raj, ‘Multi-target Tracking in a Test Range Scenario’, Defence Science Journal, vol 57, issue 03, May 2007, ISSN-00��-7��X.

[�] L Varshney, ’Technical Report Radar System Components and System Design’, November 2002, Syracuse Research Corporation.

[5] http://en.wikipedia.org/wiki/radar

P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | �3


4. nUmerical simUlation anD resUlts

The relevance of NN algorithm to a typical

Test Range scenario like ITR can be established

by testing and evaluating the algorithm for

different possible multi-target scenario. This is

accomplished by testing the algorithm by using

data from a multiple target tracking radar. Here,

the number of target tracked by the radar varies

at different instant of time. The algorithm does not

assume the maximum number of target tracked

by the sensor. In turn it identifies the number of

valid target within the field of view of the sensor

and estimates state of the targets by using the

noisy measurement from the sensor. Apart from

the nearest neighbourhood data association

algorithm, the algorithm uses a Kalman filter for

estimating the target state. The estimator uses

second order kinematics in Cartesian coordinates

for the target model.

The values assumed for the different

design parameters of Nearest Neighbourhood

algorithm are as given in Table 3.�. With these

parameter values the algorithm has been tested

for two different process noise levels as mentioned

above.

The track results of the algorithm for noise

standard deviation of 5-m, 50m and 5 m in x, y &

z directions respectively are shown in fig. �.�(a)-

�.�(c) and for noise standard deviation of 5m, 50m

and �0 m in x, y & z directions respectively are

shown in fig. �.2(a)-�.2(c).

It is seen from the track data of the Multi-

Target Tracking (MTT) radar that the elevation

measurement is very noisy and that has been

reflected in noisy altitude measurement data.

Although the estimation results in x and y position

is satisfactorily, the noisy altitude measurement

results in poor performance of altitude estimation.

Moreover, the noise standard deviation for the

sensor plays a major role in gating performance

(by computing the volume around the existing

track within which the measurement in the future

scans is likely to be). Fig �.2 brings out that the

larger noise standard deviation assumed in this

case results in a erroneous association result at

one instant (apparent from the track switching

between two targets near sample no. 790.

Table �.�

Distance threshold �00m

Redundant Threshold �00m

Prune Threshold 0

Chi Square Threshold 25

No. of Samples �000

Kalman Filter model for

target state estimation

Process noise standard

deviation

Measurement noise

standard deviation

Constant velocity

model with additive

white Gaussian noised

in acceleration

�0 m2/sec� and

�00 m2/sec� in two

different cases of the

study

5 m in x direction, 50m

in y direction and 5 &

�0m in z direction

5. conclUDinG remarKs

The nearest neighbourhood based data

association and target tracking algorithm has

been presented in this paper and the performance

of the algorithm has been established by using

multiple target tack data from a radar. The results

show that by judicious choice of error variances,

the algorithm performs satisfactorily to

estimate the kinematic state of all the targets

during the flight trials of multiple targets. Since

the algorithm utilizes track oriented approach,

the information regarding the number of

targets present in the scenario is not required

for execution of the algorithm. Exhaustive

sensitivity studies have been carried out for

the adopted algorithm and the results show

that the algorithm can perform unambiguously

even in the presence of false alarm and for very

closely spaced targets.

references

[�] S S Blackman, Multiple target tracking with radar applications, Artech House Inc., Norwood.

[2] Y Bar-Shalom, ‘Tracking methods in a multi-target environment’, IEEE Transaction on Automatic Control, Vol. AC-23, No. �, August, �97�.

[3] Shrabani, R Appavu Raj, ‘Multi-target Tracking in a Test Range Scenario’, Defence Science Journal, vol 57, issue 03, May 2007, ISSN-00��-7��X.

[�] L Varshney, ’Technical Report Radar System Components and System Design’, November 2002, Syracuse Research Corporation.

[5] http://en.wikipedia.org/wiki/radar

�� | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa


COMPATIBILIzING ABILITY OF POLYPHOSPHAzENE AND SIC COATED MWCNTS FOR THE PEI/LCP NANOCOMPOSITES - A COMPARATIVE STUDY

Chapal Kr. Das*, Ganesh Ch. Nayak*, A. Ranjan** and A. K. Saxena**

*Materials Science Centre, IIT Kharagpur, West Bengal, India

**DMSRDE Kanpur, India

Abstract

In the present study, the effect of silicone carbide (SiC) modified multiwalled carbon

nanotube (MWCNT) and polyphosphazene, as compatibilizers, in the melt-compounded

Polyetherimide (PEI)/Liquid crystalline polymer (LCP) blend was investigated in details.

From rheological study it was evident that the viscosities of the binary and ternary

blends were lower than those of the neat polymers, indicating a synergistic effect of

LCP in reducing the melt viscosity and also signifying its great ability as a processing

aid. Scanning electronic microscopic (SEM) observation had revealed that the addition

of polyphosphazene and modified MWCNT, together, results in a decrease in average

disperse domain size of LCP phase and leading to the improved filler-matrix adhesion.

Measurement of surface energy from contact angle measurements also point towards

the improved interfacial interaction, in presence of compatibilizers.

Keywords: MWCNT , Polyphosphazene, SiC coating, PEI, LCP.

1. introduction

Blending of liquid crystalline polymers (LCPs) with

thermoplastics has attracted considerable interest

for many reasons. One of these is that, under

appropriate conditions, the LCP phase can be

deformed into the fiber form, leading to so-called

in situ composites.[�–�] Secondly, addition of a

small amount of LCPs to the thermoplastics may

result in a considerable reduction in the blend melt

viscosity, thereby improving the processability

of engineering plastics.[5-7] However,

incompatibility between thermoplastic and LCPs

is an issue of major concern and this lacuna need

to be addressed in such a way that, we can achieve

polymer blends having superior mechanical,

thermal, and morphological properties. One way

to solve the afore¬mentioned problem is to use

of a compatibilizer. In recent years a large amount

of research focused on the compatibilization of

LCP blends has been published. [�-��] Baird et

al. used functionalized polypropylene, MAH-g-

PP, as a compatibilizer for the polypropylene/

LCP blends and they found improved interfacial

adhesion due to some specific interactions like

hydrogen bonding.[��-�3] Seo demonstrated

the Compatibilization of PA6/vectra B950, PA�6/

Vectra B950, PBT/Vectra A950 blends by MAH-g-

EPDM.According to Seo, some chemical reaction

between MAH groups and LCP were responsible

for the compatibilization.[��-��]. In the previous

works done at our laboratory, we had explored

the effectiveness of polyphosphazene as a

compatibilizer for the PES/LCP [�9], PEI/LCP[20]

and Nylon/LCP[2�] blends. We found that

incorporation of polyphosphazene reduced

the particle size of the LCP domains indicating

towards the improvement of compatibility

between the blend partners. We had also studied

the effect of SiC coated MWCNTs on the properties

of ABS/LCP[22] blend and improvement in the

dispersion of modified MWCNTs was noticed in

the blend matrix as compared to pure MWCNTs.

In the present work, an attempt has been made to

explore the combine effect of polyphosphazene

and SiC coated MWCNTs on the thermal,

morphology and interfacial property of PEI/LCP

blends. The goal of this study is to interpret the

effectiveness of polyphosphazene and SiC coated

MWCNT, as compatibilizer, for PEI/LCP blend.

2. experimental section:

2.1 Materials Used:

Polyetherimide (PEI), (Ultem �0�0), was

obtained from General Electric Company. Liquid

crystalline polymer (Vectra A950) was supplied by

Ticona, USA. This LCP is wholly aromatic copolyester

containing 25 mol% of 2, 6-hydroxynaphthoic acid

(HNA) and 75 mol% of p-hydroxybenzoic acid (HBA).

Polyphosphazene which has been used in

this research work was made by us in the laboratory

of applied chemistry division, DMSRDE, Kanpur,

India. Polyphosphazene used in this research

work are having inorganic backbone skeletal

(P=N) with various organic pendant groups. The

chemical structures of the components used, are

given in figure �.

The MWCNTs (MWCNTs-�000) were from

IIjin Nano Technology, Korea. The diameter, length

and aspect ratio were �0–20 nm, 20 µm and ~�000,

respectively. The density of MWCNT is 2.�6 g/cm3.

Figure 1: Chemical structure of PEI, LCP and

Polyphosphazene

2.2 Modification of MWCNT with silicon carbide

(SiC)

The procedure for modification is as

follows [22]:

i. Solid-state polycarbosilane (PCS) (Indigenously made

by DMSRDE, Kanpur, Mw ~ ��00) is put in a beaker

containing 50 ml of n-hexane, and ultrasonically

dissolved using a horn type ultrasonicator.

ii. Then, the MWCNTs (IIjin Nano Technology,

Korea.) are introduced to the PCS solution and

then ultrasonically dispersed for 30 min at 60oC.

The weight ratio of PCS/ MWCNTs was 3/7.

Invited Paper



COMPATIBILIzING ABILITY OF POLYPHOSPHAzENE AND SIC COATED MWCNTS FOR THE PEI/LCP NANOCOMPOSITES - A COMPARATIVE STUDY

Chapal Kr. Das*, Ganesh Ch. Nayak*, A. Ranjan** and A. K. Saxena**

*Materials Science Centre, IIT Kharagpur, West Bengal, India

**DMSRDE Kanpur, India

Abstract

In the present study, the effect of silicone carbide (SiC) modified multiwalled carbon

nanotube (MWCNT) and polyphosphazene, as compatibilizers, in the melt-compounded

Polyetherimide (PEI)/Liquid crystalline polymer (LCP) blend was investigated in details.

From rheological study it was evident that the viscosities of the binary and ternary

blends were lower than those of the neat polymers, indicating a synergistic effect of

LCP in reducing the melt viscosity and also signifying its great ability as a processing

aid. Scanning electronic microscopic (SEM) observation had revealed that the addition

of polyphosphazene and modified MWCNT, together, results in a decrease in average

disperse domain size of LCP phase and leading to the improved filler-matrix adhesion.

Measurement of surface energy from contact angle measurements also point towards

the improved interfacial interaction, in presence of compatibilizers.

Keywords: MWCNT , Polyphosphazene, SiC coating, PEI, LCP.

1. introduction

Blending of liquid crystalline polymers (LCPs) with

thermoplastics has attracted considerable interest

for many reasons. One of these is that, under

appropriate conditions, the LCP phase can be

deformed into the fiber form, leading to so-called

in situ composites.[�–�] Secondly, addition of a

small amount of LCPs to the thermoplastics may

result in a considerable reduction in the blend melt

viscosity, thereby improving the processability

of engineering plastics.[5-7] However,

incompatibility between thermoplastic and LCPs

is an issue of major concern and this lacuna need

to be addressed in such a way that, we can achieve

polymer blends having superior mechanical,

thermal, and morphological properties. One way

to solve the afore¬mentioned problem is to use

of a compatibilizer. In recent years a large amount

of research focused on the compatibilization of

LCP blends has been published. [�-��] Baird et

al. used functionalized polypropylene, MAH-g-

PP, as a compatibilizer for the polypropylene/

LCP blends and they found improved interfacial

adhesion due to some specific interactions like

hydrogen bonding.[��-�3] Seo demonstrated

the Compatibilization of PA6/vectra B950, PA�6/

Vectra B950, PBT/Vectra A950 blends by MAH-g-

EPDM.According to Seo, some chemical reaction

between MAH groups and LCP were responsible

for the compatibilization.[��-��]. In the previous

works done at our laboratory, we had explored

the effectiveness of polyphosphazene as a

compatibilizer for the PES/LCP [�9], PEI/LCP[20]

and Nylon/LCP[2�] blends. We found that

incorporation of polyphosphazene reduced

the particle size of the LCP domains indicating

towards the improvement of compatibility

between the blend partners. We had also studied

the effect of SiC coated MWCNTs on the properties

of ABS/LCP[22] blend and improvement in the

dispersion of modified MWCNTs was noticed in

the blend matrix as compared to pure MWCNTs.

In the present work, an attempt has been made to

explore the combine effect of polyphosphazene

and SiC coated MWCNTs on the thermal,

morphology and interfacial property of PEI/LCP

blends. The goal of this study is to interpret the

effectiveness of polyphosphazene and SiC coated

MWCNT, as compatibilizer, for PEI/LCP blend.

2. experimental section:

2.1 Materials Used:

Polyetherimide (PEI), (Ultem �0�0), was

obtained from General Electric Company. Liquid

crystalline polymer (Vectra A950) was supplied by

Ticona, USA. This LCP is wholly aromatic copolyester

containing 25 mol% of 2, 6-hydroxynaphthoic acid

(HNA) and 75 mol% of p-hydroxybenzoic acid (HBA).

Polyphosphazene which has been used in

this research work was made by us in the laboratory

of applied chemistry division, DMSRDE, Kanpur,

India. Polyphosphazene used in this research

work are having inorganic backbone skeletal

(P=N) with various organic pendant groups. The

chemical structures of the components used, are

given in figure �.

The MWCNTs (MWCNTs-�000) were from

IIjin Nano Technology, Korea. The diameter, length

and aspect ratio were �0–20 nm, 20 µm and ~�000,

respectively. The density of MWCNT is 2.�6 g/cm3.

Figure 1: Chemical structure of PEI, LCP and

Polyphosphazene

2.2 Modification of MWCNT with silicon carbide

(SiC)

The procedure for modification is as

follows [22]:

i. Solid-state polycarbosilane (PCS) (Indigenously made

by DMSRDE, Kanpur, Mw ~ ��00) is put in a beaker

containing 50 ml of n-hexane, and ultrasonically

dissolved using a horn type ultrasonicator.

ii. Then, the MWCNTs (IIjin Nano Technology,

Korea.) are introduced to the PCS solution and

then ultrasonically dispersed for 30 min at 60oC.

The weight ratio of PCS/ MWCNTs was 3/7.

Invited Paper



iii. The resultant suspension is then dried naturally

in a draft chamber at 25oC in order to remove

n-hexane.

iv. Then, the PCS–MWCNTs mixture is put into a

quartz crucible and is cured at 2�0oC for 90

minutes under an oxidizing atmosphere, in

order to prevent agglomeration of PCS during

subsequent high temperature treatments.

v. Finally, the product obtained in the previous

step is heat-treated at ��50oC in oven for one

hour in argon atmosphere.

2.3 Preparation of composites

Prior to mixing PEI and LCP and polyphosphazene

are dried under vacuum at �0 oC and MWCNTs

at 200 oC for �2 hours. PEI/LCP composites with

polyphosphazene and SiC modified MWCNTs

are prepared by melt blending in a sigma high

temperature internal mixture equipped with two

Sigma type counter rotating rotors. The blending

compositions were presented in the table �.

Blending is carried out at 330 oC and �00 rpm. One

set of pure PEI/LCP binary blend also prepared by

the same route for comparison. Samples for the

mechanical testing are prepared by compression

molding at 350 oC using �0 MPa pressure and

then allowed to cool to room temperature.

3. characterization

3.1 Scanning electron Microscopy (SEM)

The fractured surface of the blend

systems were analyzed by using a Tescan VEGA

LSU SEM. Before the analysis the fractured surfaces

were sputtered with gold for making the surface

conducting.

3.2 Rheology

Rheology study is carried out in a Capillary

Rheometer (Smart RHEO �000, CEAST) at 330oC, at

different shear rates, to investigate the effect of

polyphosphazene and modified MWCNTs on the

viscosity of PEI/LCP blend.

3.3 Mechanical Properties

Tensile tests are carried out on dumb-bell

shaped samples using a Hounsfield HS �0 KS (universal

testing machine) operated at room temperature with

a gauge length of 35 mm and crosshead speed of

5mm/min. Tensile values reported here are an average

of the results for tests run on at least four specimens.

3.4 Thermogravimetric Analysis (TGA)

Thermogravimetric analysis curves were

recorded with a Dupont 2�00 thermogravimetric

analyzer. The TGA measurements were conducted

with a heating rate of �0oC/min under air

atmosphere from �00 to 650oC.

4. results and Discussion

4.1 Morphological Study

The fracture surfaces of binary and ternary

blends were investigated using SEM and the

images were presented in figure 2(a-d). Figure 2a

depicted the SEM micrograph of PEI/LCP (B) binary

blend system. It showed that, spherical domains

Table 1: Sample codes and formulation of

nanocomposites

Sample PEI LCP Polyphosphazene MWCNT

Code (Wt%) (Wt%) (Wt%) (Wt%)

A �00 - - -

B 75 25 - -

C 75 22.5 2.5 -

D 75 22.5 - 2.5

E 75 20 2.5 2.5



of LCPs were distributed in the PEI matrix with an

average particle size of �.02 µm (measured using

the VEGA LSU SEM software). The voids shown

in the Figure 2a were formed due to the pullout

of the LCP phase from the PEI matrix, indicating

towards the poor adhesion at the interface of

PEI and LCP. Addition of polyphosphazene to the

PEI/LCP blend reduced the average particle size of

LCP to 6.27 µm and a reduction in the LCP pullouts

also observed, as compared to PEI/LCP blend

system. This indicates towards the improvement of

interfacial adhesion at the PEI/LCP interface due to

the compatibilization effect of polyphosphazene

(Figure 2b). However, incorporation of SiC¬modified

MWCNTs (D) showed further reduction in the

average particle size (5.62 µm, which is clear from

Figure 2c) suggesting a better interfacial adhesion

at the interface.

The difference between the blend systems

with polyphosphazene (sample C) and with SiC

coated MWCNTs (sample D), was the shape of the LCP

domains and the fibrillation of LCP. The system with

polyphosphazene showed spherical domains of LCP

without any LCP fibrillation while the system with SiC

coated MWCNTs shows slight deformation of the LCP

domains to ellipsoidal form with a little fibrillation

on there surfaces. We proposed a mechanism for the

above observed morphology as follows:

Since PEI and LCP were incompatible with each

other, during melt blending there will be a

slippage between the two phases (due to the

poor adhesion at the interface) which reduces the

chances of LCP deformation to form fibers out of

it. Due to this reason, only spherical domains of

LCPs were formed in the binary blend system. The

voids observed in the fracture surface of binary

blend were formed by the pullout of LCP domains

during fracture process. In the ternary blend C,

polyphosphazene was acting as a compatibilizer

between the blend partners and hence step up

the interfacial adhesion due to which the LCP

domains were broken into smaller particles and

average particle size was reduced. However, in the

SiC coated MWCNTs added system the nanotubes

might acting as a bridging agent between the

two phases and hence helped in dragging the

LCP phase along the flow direction, during mixing,

which deform the spherical LCP domains to

slightly ellipsoidal form. The rougher surface of SiC

coated MWCNTs decreased the slippage of these

modified MWCNTs at the interface and hence

slight fibrillation was observed in these samples. If

this proposed mechanism is true then addition of

both polyphosphazene and SiC coated MWCNTs

to the PEI/LCP blend should give rise to more

fibrillation in the system due to the combined

effect of polyphosphazene and SiC coated

MWCNTs. The above mentioned inference was

found in figure 2d. As we can see the LCP domains

were completely fibrillated for the system E.

(a) (b) (c) (d)

Figure 2: SEM image of (a) PEI/LCP, (b) PEI/LCP/Polyphosphazene, (c) PEI/LCP/SiC coated MWCNTs and (d) PEI/LCP/SiC coated MWCNTs /Polyphosphazene blends



4.2 Rheological Study

The flow properties of pure PEI, and its

respective blends (B, C, D, and E) were investigated

at 330oC using a capillary rheometer. The viscosity–

shear rate relationship for the pure PEI and the

blends were shown in Figure 3. The viscosities of

the binary and the ternary blends were found to

be lower than that of the pure PEI, which indicating

towards the ability of LCP as a processing aid in

these blend systems. The binary blend of PEI/

LCP is having the lowest viscosity among all the

blend systems which may be due to the following

factors i. The incompatibility between the two phases

gives rise to interlayer slippage between the PEI and LCP phases and hence reducing its viscosity.[23]

ii. Under the shear force (in the capillary rheometer) the LCP domains might align in the direction of the flow and hence enhance the

melt flow and reduce the melt viscosity.

modified MWCNTs which is due to presence of

these modified MWCNTs at the interface of PEI and

LCP and acting as a bridging agent between the

two phases. We had found in our previous work

[22] that the coating of SiC makes the MWCNTs

surface rougher which restricts the slippage of

these modified nanotubes from the polymer

matrix. The same phenomenon might also occur

at the interface of PEI and LCP where nanotubes

reduced the chain slippage at the interface which

increases the viscosity of the PEI/LCP/SiC coated

MWCNTs blend system. However the distribution

of SiC coated MWCNTs in bulk also can increase

the viscosity. But viscosity of blend system with

both polyphosphazene and SiC coated MWCNTs

appears to be the lower than the blends with only

polyphosphazene and SiC coated MWCNTs. This is

due to the formation of LCP fibers during mixing

which were aligned along the flow direction and

reduces the viscosity of this blend system in the

capillary rheometer analysis.

4.3 Mechanical Properties

Variations in mechanical properties of pure matrix

along with the blends were shown in Figure

�a&b. In binary blend system (B), tensile strength

decreases as compared to pure PEI matrix (A),

indicating the poor adhesion between the matrix

phase and dispersed phase. In case of PEI/LCP/

polyphosphazene blend system (C), the tensile

strength, and tensile modulus was found to be

increase in comparison to PEI/LCP blend system

(B) suggesting an enhancement of interfacial

adhesion between the PEI and LCP matrix which

helps in the stress transfer from the PEI phase to

the LCP phase and thus improves both tensile

strength and modulus of the blend. However,

the elongation at break has also increased with

Figure 3: Rheological properties of pure PEI and its blends with LCP

The polyphosphazene compatibilized

blend exhibits a rise in viscosity, in comparison

to uncompatilized binary blend because of the

restricted interlayer slippage between the PEI

and LCP phase, by the presence of compatibilizers

at the interface. The rise in viscosity is most

pronounced in case of PEI/LCP blend with SiC-



the addition of polyphosphazene indicating the

plasticizing effect of polyphosphazene in making

the blend flexible in nature. The tensile strength,

and modulus of PEI/LCP/SiC-modified MWCNTs (D)

blend system showed higher value in comparison

to PEI/LCP blend system but elongation at break

had followed the usual way, i.e., it was decreased

for the PEI/LCP/2.5 wt% SiC-modified MWCNT

composites. The probable reasons behind this

enhancement in tensile strength and modulus are

as follows [2�]: (i) Bridging effect of SiC coated MWCNTs at the PEI

and LCP interface (discussed in the morphology section), which requires more energy to pull out the LCP phase and thus resists the fracture which increased the tensile strength.

(ii) Presence of SiC coated MWCNTs in the bulk matrix enhanced the stress transfer from the matrix to the MWCNTs hence improves the modulus.

However, for combine addition of SiC

coated MWCNTs and polyphosphazene to the PEI/

LCP blend (E) shows a synchronous improvement

in strength and modulus. The enhancement in

tensile strength may be ascribed to the mechanical

reinforcement offered by SiC-modified MWCNTs.

4.4 Thermal Stability

Thermal stability of the composites is

graphically represented in Figure 5. As showed in

the figure 5, binary blend of PEI/LCP (B) followed a

two-step degradation process at �52oC and 527oC.

Addition of 2.5% of polyphosphazene (C) and

SiC modified MWCNTs (D) to the PEI/LCP blend

increased the first onset degradation temperature

to �70 and �7�oC respectively, which suggested

that the polyphosphazene and SiC modified

MWCNTs aided blend systems were more thermal

stable as compared to the uncompatibilized

blend system (B). However, addition of both SiC

modified MWCNTs and polyphosphazene to the

PEI/LCP blend (E), improved the thermal stability

of the composite to �9�oC. The superior thermal

stability of E can be apparently attributed to the

restricted motion of polymer chains due to SiC

modified MWCNTs [25] and compatibilization

effect of polyphosphazene between the PEI matrix

and dispersed LCP phase. [20]

(b)

(a)

Figure 4: Tensile properties of different PEI/LCP blend

systems (a)Tensile Modulus and (b) Tensile Strength Figure 5: TGA analysis of pure PEI and its blends with LCP



5. conclusions

Ternary blends of PEI/LCP with

polyphosphazene and SiC modified MWCNTs

were prepared by melt blending. Rheological

study confirms that viscosity of ternary blends

exhibit higher value in comparison to binary

blend system. Combination of polyphosphazene

and SiC modified MWCNTs in PEI/LCP blend has

improved the tensile strength and tensile modulus

as compared to binary and ternary blends as well

as pure PEI. In presence of polyphosphazene,

reduction in number average particle size of LCP

was observed as compared to PEI/LCP binary

blend. SEM study reveals that the fibrillation of

LCP in presence of SiC modified MWCNTs and

polyphosphazene.

6. references

[�] Kiss G. Polym. Eng. Sci. �9�7; 27:��0-�23. [2] Handlos V, Baird D G. J. Macromol. Sci. Rev. C. �995;

35(2):��3-23�. [3] Crevecour G., Groeninckx G. Polym Comp.�992; �3

(3):2��-250. [�] Seo Y, Kim B, Kwak S, Kim K U, Kim J. Polym. �999;

�0 (�6): ��-��50. [5] Kohli A., Chung N, Weiss A R. Polym Eng Sci.

�9�9;29:573. [6] Croteau J F, Laivins G V. J. of App. Poly. Sci. �990;39:

2377. [7] Malik T Q, Carreau P J, Chaplean N. Polym Eng Sci.

�9�9;29:600. [�] Seo Y, Hong S M., Hwang S S, Park T S, Kim K U, Lee

S Lee. J. Polymer.�995; 36:5�5. [9] Yongsok S, Soon M H, Kwang U K. Macromolecules.

�997;30: 297�. [�0] Dutta D, Weiss R.A. Polym. Compos. �992; �3:39�. [��] Datta A., Chen H.H., Baird D G. Polymer.

�993;3�:759. [�2] Datta A, Baird D G, Polymer. �995;36:505.

[�3] O’Donnell H J, Baird D G. Polymer. �995;36:3��3. [��] Seo Y, J Appl Polym Sci. �997;6�:359. [�5] Seo Y, Hong S M, Kim K U. Macromolecules.

�997;30:297�. [�6] Seo Y, Kim K U. Polym Engg Sci. �99�;3�:5�3. [�7] Seo Y. J Appl Polym Sci. �99�;70:�5�9. [��] Seo Y, Kim B, Kim K U. Polymer. �999;�0:��3. [�9] Bose S, Mukherjee M, Das C K, Saxena A K. Polymer

Composites. 2009;3�:5�3. [20] Bose S, Pramanik N, Das C K, Ranjan A, Saxena A K.

Materials and Design. 2009;3�:��. [2�] Bose S, Mukherjee M, Rath T, Das C K. J Reinf plast

Comp. 2009;2�: �57. [22] Bose S, Mukherjee M, Pal K, Nayak G C, Das C K.

Polym Advan Technol.2009:2�:272. [23] Utarcki L A, Kamal MWCNTs R. Polymer Blends

Handbook Vol.�. Netherlads: Kluwer Academic publisher; 2002.

[2�] Sachariades A, Porter P S. High Modulus Polymer. New York: Marcel Dekker;�9��.

[25] Lozano K, Barrera E V. J. Appl Polym Sc. 200�;79:�25.

P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa | 2�


MATERIALS FOR BALLISTIC APPLICATIONS

Basudam Adhikari

Materials Science Centre, Indian Institute of Technology, Kharagpur 72�302

E. Mail: [email protected]

Prior to the development of synthetic polymers,

metals and ceramics were the classical materials

for battlefield devices till the World War II. War

situations in �9�0s compelled the superpowers to

develop technologies for manufacturing synthetic

polymers especially synthetic rubbers and other

high performance polymers. Revolutionary

research on polymers exploded in two decades

following the World War II in American and

European countries and the result is the success

in polyolefin technology and the award of Noble

Prize to ziegler and Natta. Beyond �970s there is an

outburst of technological development in polymers

including other strategic materials. Polymers with

high strength, toughness and thermal stability

have been developed. Nanocomposites are

stronger, creating greater durability and requiring

less total material. It has been established that

nanotechnology will produce a host of advanced

materials with unprecedented strength and

versatility. Although polymeric materials produce

relatively soft devices but metals and ceramics are

also used in combination to obtain a balance of

ultimate performance. Since ballistic armor uses a

host of polymers, ceramics and metals an overview

of application of these materials is presented in

this lecture.

A ballistic vest, bulletproof vest or bullet-

resistant vest is an item of personal armor to

absorb the impact from firearm-fired projectiles

and shrapnel from explosions. In ballistic vest

layers of very strong fiber are used. In fact a

bullet is caught, deformed and mushroomed

into a dish shape, and its force is spread over a

larger portion of the vest fiber. The vest absorbs

the energy from the deforming bullet, bringing it

to a stop before it can completely penetrate the

textile matrix. On the contrary vests designed

for bullets are not suitable for sharp weapons

such as knives, arrows, etc. due to concentrated

impact force, which punctures the fiber layers of

the vest fabric. As a measure of extra protection

sometimes textile vests are supported with

metal (steel or titanium), ceramic or polyethylene

plates. Vests which are designed specifically

against bladed weapons and sharp objects may

incorporate coated and laminated para-aramid

textiles or metallic components.

Invited Paper



research Progress in Ballistic Vests

Advances in material science have opened the

door for bulletproof vest to stop handgun and

rifle bullets with a soft textile vest, viz., Kevlar

without additional metal or ceramic plating.

The para-aramids have not progressed beyond

the limit of 23 grams per denier in fiber tenacity.

Improvements in ballistic performance have also

been made by UHMWPE fiber. The basic fiber

properties have been improved to the 30–35

g/d range. The major ballistic performance of

poly-p-phenylenebenzobisoxazole (PBO) fiber

is also known [Tooru Kitagawa, Hiroki Murase,

Kazuyuki Yabuki, Morphological Study on Poly-p-

phenylenebenzobisoxazole (PBO) Fiber, Journal of

Polymer Science: Part B: Polymer Physics, Vol. 36,

39–�� (�99�)]. This fiber permitted the design of

handgun soft armor that was 30–50% lower in

mass as compared to the aramid and UHMWPE

fibers.

Spider silk fibers spun from soluble

recombinant silk produced in mammalian cells is

considered as a second generation “super” fibers

although the science of this material is complex.

Spider dragline silk is a flexible, lightweight

fiber of extraordinary strength and toughness

comparable to that of synthetic high-performance

fibers. The process of spider silk production was

biomimicked by expressing the dragline silk

genes (ADF-3/MaSpII and MaSpI) of two spider

species in mammalian cells and produced soluble

recombinant (rc)-dragline silk proteins with

molecular masses of 60 to ��0 kilodaltons. The

wet spinning of silk monofilaments spun from

a concentrated aqueous solution of soluble rc-

spider silk protein (ADF-3; 60 kilodaltons) was

done. The water insoluble spun fibers had a �0

to �0 µm diameter and toughness and modulus

values comparable to those of native dragline

silks but with lower tenacity. Further research aims

to develop artificial spider silk which could be

super strong, yet light and flexible. Simultaneous

research is underway to harness nanotechnology

to help create super-strong fibers that could be

used in future bulletproof vests [Anthoula Lazaris,

Steven Arcidiacono, Yue Huang, Jiang-Feng zhou,

François Duguay, Nathalie Chretien, Elizabeth A.

Welsh, Jason W. Soares, Costas N. Karatzas, Spider

Silk Fibers Spun from Soluble Recombinant Silk

Produced in Mammalian Cells, Science 295 (555�):

�72–�76].

A new type of carbon fibre, developed at

the University of Cambridge is reported. This fiber

could be woven into super-strong body armour for

the military and law enforcement. The inventors of

this fiber claimed that this material is several times

stronger, tougher and stiffer than fibres currently

used to make protective armour. The lightweight

fibre, made up of millions of tiny carbon nanotubes,

is also known to reveal exciting properties. Carbon

nanotubes are hollow cylinders of carbon just one

atom thick. This material was developed by Alan

Windle et al. (Science, 2007) at the Department of

Materials Science and Metallurgy at University of

Cambridge. Windle claimed that these nanotube

fibers can be woven as a cloth, or incorporated

into composite materials to produce super-strong

products, i.e., very strong, lightweight and good

at absorbing energy. This fibre is someway better

than the existing high performance Kevlar fibres.

It appears that this new material can also find

applications in the area of hi-tech “smart” clothing,

bomb-proof refuse bins, flexible solar panels, and,

eventually, as a replacement for copper wire in

transmitting electrical power and signals.



A high performance M5 fiber based on the

rigid-rod polymer poly [diimidazo pyridinylene

(dihydroxy) phenylene] was developed for

ballistics / structural composites [Cunniff, Philip

M.; Auerbach, Margaret; Vetter, Eugene; Sikkema,

Doetze J. High Performance “M5” Fiber for

Ballistics/Structural Composites, http://web.mit.

edu/course/3/3.9�/OldFiles/www/slides/cunniff.

pdf.]. The ballistic impact potential of this fiber-

based armor system was estimated using an

“armor materials by design” model for personnel

armor. The model was based on a dimensional

analysis of the mechanical properties of the

fibers used to construct the armor system. The

performance of these armor systems was found

to be exceptional.

textile wovens and laminates research

Finer yarns and lighter woven fabrics are key

factors in improved ballistic performances.

Decreasing the yarn size increases the cost of

ballistic fiber. The current practical limit of fiber

size is 200 denier with most woven fabrics limited

at the �00 denier level. A study on the ballistic

impact characteristics of Kevlar woven fabrics

impregnated with a colloidal shear thickening fluid

[Young S. Lee, E. D. Wetzel N. J. Wagner, The ballistic

impact characteristics of Kevlar woven fabrics

impregnated with a colloidal shear thickening

fluid, Journal of Materials Science, 3� (2003)

2�25 – 2�33] reports the ballistic penetration

performance of a composite. The composite is

made of woven Kevlar fabric impregnated with a

colloidal shear thickening fluid (silica particles (�50

nm) dispersed in ethylene glycol). The composite

exhibited penetration resistant characteristics.

Ballistic penetration measurements at 2�� m/s

were performed to demonstrate the efficacy of

this composite. A significant enhancement in

ballistic penetration resistance was demonstrated.

The reason was due to the addition of shear

thickening fluid to the fabric, without any loss in

material flexibility.

Developments in ceramic armor

The use of small ceramic components is an area

of special activity pertaining to vests. Ceramic

materials, their processing and progress in ceramic

penetration mechanics have been identified as

significant areas required for ceramic armor. While

large torso sized ceramic plates are complex to

manufacture as well as subject to cracking in

use, monolithic plates also have limited multi hit

capacity as a result of their large impact fracture

zone. These have become the motivations for new

types of armor plate comprising new designs of

2 and 3 dimensional arrays of ceramic elements

that can be rigid, flexible or semi-flexible. The

manufacture of array type systems with flex,

consistent ballistic performance at edges of ceramic

elements is an active area of research. A ceramic

armor material database has been reported [T. J.

Holmquist; A. M. Rajendran; D. W. Templeton; K. D.

Bishnoi; http://www.stormingmedia.us /62/6292/

A629263.html]. Experimental data obtained from

numerous journals and conference proceedings

have been reported. The data on nine different

ceramic materials are presented. The ceramics are:

silicon carbide, boron carbide, titanium diboride,

aluminum nitride, silicon nitride, aluminum

oxide (�5% pure), aluminum oxide (high purity),

tungsten carbide and glass. For each ceramic

material experimental data are presented based

on: mechanical tests, hydrostatic tests, plate

2� | P. G. Department of Applied Physics and Ballistics, F. M. University, Balasore, Orissa


impact tests, semi-infinite penetration tests, depth

of penetration (DOP) tests, perforation tests and

other tests.

nanomaterials in ballistics

With the progress in nanotechnology a number

of methods are being implemented incorporating

nanomaterials in body armor production. One

good example is the use of shear thickening fluids

(silica particles (�50 nm) dispersed in ethylene

glycol) in woven Kevlar fabric. The suit produced in

this way is rigid enough to protect the wearer as

soon as a kinetic energy threshold is surpassed. In

another development it was demonstrated that

a nanocomposite based on tungsten disulfide

nanotubes was able to withstand shocks generated

by a steel projectile traveling at velocities of up to �.5

km/s. The material was also reported to withstand

shock pressures generated by the impacts of up to

250 MT-force/cm2 (2�.5 GPa; 3,550,000 psi). During

the tests, the material proved to be so strong that

after the impact the samples remained essentially

unmarred. A recent study in France tested the

material under isostatic pressure and was found to

be stable up to at least 3� GPa. In mid-200�, spider

silk bulletproof vests and nano-based armors were

developed for potential market release. Both the

British and American militaries have desired to use

woven carbon fiber fabric from carbon nanotubes

that was developed at University of Cambridge for

use as body armor.



DOPING IN SEMICONDUCTOR NANOCRYSTALS

Narayan Pradhan

Department of Materials Science

Indian Association for the Cultivation of Science

Jadavpur, Kolkata 700032, India

Email: [email protected]

Abstract:

Light emitting semiconductor nanocrystals (quantum dots or Q-dots) have been

attracting interest over the last two decades in view of enormous technological

possibilities in various fields, particularly in the field of display or lighting devices and

in biological labelling or diagnostic. These are the direct band gap semiconductor

nanocrystals where the exciton of the nanocrystals recombines within the valence and

conduction bands of the nanocrystals and provides size dependent tunable emission.

In recent progress, doped semiconductor nanocrystals are emerged as new series of

nanocrystal emitters which are not only intense but also associated with several other

advantages i.e. larger Stoke shift, minimized self-absorption, thermal and environmental

stability etc. These nanocrystals are made by doping different transition metal ions in

semiconductor host nanocrystals which allows the host exciton to recombine by this/

these additional energy state/s. A detail study of the doping, particularly the emission

properties and its comparison with undoped nanocrystals are presented in this

manuscript.

introduction:

Semiconductor nanocrystals with size tunable

optical emissions�-3 have been extensively studied

as light emitting source for LEDs,� lasers,5 bar-

coding,6 biological labeling2,7 and chemical

sensing� etc. These highly emissive nanocrystals

with tunable, narrow and stable emission are

mostly direct band gap inorganic semiconductors

where the generated exciton relaxes within their

valance and conduction bands.�-3, 9 Apart from this

direct exciton relaxation, introducing additional

impurity or dopant states in between the

valance and conduction band diverts the exciton

relaxation process through these additional

energy states leading to intense dopant related

Invited Paper



emission at host excitations.�0-�6 These dopant

related emission compete with tunable exciton

emission for the comparable intensity, stability�7

and other related photo-physical aspects for

different applications.��,�9

The photo-physical properties and

particularly the choice of the exciton of the

nanocrystals to select the allowed path for

recombination when more than one possible

channel is present remained important to govern

the optical properties of nanocrystals. Among

different transition metal ions dopants Mn and

Cu are the well studied one and provide stable,

tunable and bright emission. �0-�6 Similarly, a

larger number of hosts both in group II-VI and

group III-V semiconductor nanocrystals can be

chosen to provide the excitation. znSe, znS and

alloy of CdznS, having well established synthetic

protocols have been explored for doping either

Mn or Cu to provide different emissions.�0-�2 Figure

� shows the emission color (images) of undoped

znSe and three different emissions in longer

wavelength but in visible window on doping

Mn and Cu ions. This spectacular change of light

emission attracts researcher to understand the

novelty of the synthesis as well as the new photo-

physical properties.

The appropriate condition to allow

the exciton to relax via the dopant states is the

selection of hosts which should have high band

gap and should accommodate these dopant states

within their valence and conduction bands. Figure

2 shows the schematic presentation of the band

structure of a semiconductor and the possible

existence of Cu and Mn states. Mn provides its two

excited states in between the host band gap, and

both hole and electron of the host exciton migrate

to Mn states.�0-�2 The recombination within these

Mn states provides the orange emission. This

emission, as it depend on the Mn bands remains

mostly non-tunable with tuning the size and

composition of hosts. But there are several reports

of small range tuning because of the interaction of

ligands on the crystal field of Mn (d5).�2 However,

Cu follows a different mechanism. Even though

the exact origin of Cu emission is not yet known

but the widely acceptable mechanism suggests

that Cu provides t2 states just above the valance

band of the host nanocrystals and only the hole

of the host exciton migrates to these states.20, 2�

The recombination occurs within the electron in

the conduction band of the host nanocrystals and

the hole in Cu states, and hence the emission is

expected tunable as the conduction band of the

host tunes with tuning size and composition of

the nanocrystals.

Figure 1. Digital images from the reaction flasks of ZnSe and after doping with Copper, Manganese and Manganese with sulphur. Undoped ZnSe emits blue and doping with Cu provides tunable emission and green is the best one. Doping with Mn, ZnSe emits yellow and in presence of additional ligand (S), the yellow emission changes to red. Excitation wavelength is 365 nm. The UV lamp used has power 6 mw.



nanocrystals where the excitation band overlaps

with the emission band, in that case the emission

energy again used to excite the nanocrystals. When

the concentration of the sample increases, it is more

pronounced.22 This is a disadvantage characteristic

as while these nanocrystals are used for making

a device where larger number of materials are

used, in that case the overall emission decreases

with increase of nanocrystal concentration. In

undoped quantum dots, this happens and hence

to explore nanocrystal emitters for making device,

nanocrystals should have minimized or no self-

absorption i.e. should have large Stoke shift.

Doped nanocrystals are perfect example of this

category. As introduced dopant sates shifts the

emission band to longer wavelength, the Stoke

shift became larger and hence the chance of self-

absorption reduces. For the case of Mn doped znS,

Mn doped znSe, almost no reabsorption has been

In this communication, we report the

photophysical processes involved in various

doped nanocrystals to understand the possible

electronic transition and explained the nature

and properties of these emissions, change of

excited state lifetime and possible interference

with surface states, and also all these properties

are compared with undoped nanocrystals. Some

of the observations we have obtained agree with

the old reports and some are found new to provide

more information to understand the fundamental

aspects of electronic transition of these newly

developed doped nanocrystals.

results and Discussion

Self-Absorption:

Self-absorption or reabsorption of the

nanocrystal emitters is very common. For those

Figure 2. Schematic presentation of possible excitonic recombination paths of (a) undoped quantum dot, (b) Mn doped and (c) Cu doped nanocrystals. Two intermediate states in (b) are 4T1(4G) - 6A

1(6S) of Mn. The

intermediate state of Cu in (c) is t2 states of Cu.



observed and for Cu doped nanocrystals (znS,

or znSe), minimized reabsorption is there which

contributes negligible amount for the overall

emission quenching.�2 Figure 3 shows the emission

of nanocrystals with changing the secondary

Figure 3. (a) A schematic presentation of the measurement in Fluoremeter sample chamber. The secondary pathlength is towards the detector. Changing this path length photoluminescence (PL) has been measured. Emission changes for undoped nanocrystals is in (a) and doped nanocrystals is presented in (b).

pathlength of the sample for undoped and doped

semiconductor nanocrystals. It indicates that the

emission intensity decreases with increase of

secondary pathlength and unaltered for doped

nanocrystals.



Excited State Lifetime and the Photo-Physical

Process:

As nanocrystals show emission, it is

associated with some excited state lifetime. This is

the time of the exciton takes for the recombination.

For undoped nanocrystals, which show size

tunable emission the excited state lifetime is

in nano seconds.23 This emission is the exciton

emission which positioned at the band edge

absorption of the nanocrystals. But for doped

nanocrystals, it varies and certainly the lifetime

falls in higher order than in nanosecond.�� For the

case of Mn doped nanocrystals, it is found that the

excited state lifetime remains in millisecond which

is much higher than the excitonic emission.�0 In

fact the recombination within the Mn states is d-

d forbidden and that enhances the lifetime of this

yellow emission.�0 This is a perfect tool to distinguish

the Mn dopant emission from band edge excitonic

emission. Next, for Cu doped nanocrystals whose

emission tunes with their size, the excited state

lifetime falls mostly in microseconds or hundreds

of nanoseconds which is also in much higher order

than the band edge emission.�7 Unlike Mn dopant

emission, the lifetime of Cu dopant emission tunes

with the emission tuning. Once the emission red

shifts, the lifetime of Cu dopant emission increases.

Similar trend has been observed for the excitonic

emission of the band edge emission but they are

difference in their excited state lifetime.2� Typical

lifetime plots for Mn and Cu doped nanocrystals

are shown in Figure �.

Figure 4. Lifetime decay plot for Mn doped ZnS (b) and Cu doped ZnCdS alloy.

Functionalization and Solubility:

Semiconductor nanocrystals, either

doped or undoped, they are synthesized mostly

at high reaction temperature in solution and

hence they are hydrophobic in nature. To use

them in Biology or different other potential

applications they need to be water soluble

or surface modification. Keeping the quality

of nanocrystals same, surface organics are

exchanged with appropriate new organic/s as

per the requirement.25 One of the successful

attempts to make water them soluble is using

mercaptopropionic acid or (or mercaptocarboxylic

acids) where one end has thiol which binds to the



inorganic nanocrystal surfaces26, 27 and other end has

carboxylic acid which makes them water soluble.

To use these materials in LED, they are embedded

with sometimes appropriate polymer to make a

good film. The problem of this surface modification

which is called surface functionalization is not easy.

This has high chance of creating additional energy

states mostly due to surface oxidation. These

states hinder the exciton relaxation process and

sometimes they behave like non-radiative channel

or create another emission at longer wavelength.

One of the advantages of doped nanocrystals is

that the excitonic process is not harmed with these

surface states. Even the surface gets oxidized, the

exciton follows the more allowed dpant states and

hence the emission is not quenched like undoped

nanocrystals. This helps to make them a potential

candidate for various applications.

Thermal Stability and Photo-Stability:

Undoped quantum dots has phonon

coupling and hence with increase of temperature

the emission intensity decreases. This is a

disadvantage for these nanocrystals for their

application is light emitting devices as heat can

generate for long time use which can reduce the

emission intensity. It is found that within �50 oC,

the emission of CdSe nanocrystals completely

quench.22 However, this process is reversible

and during cooling the emission reappears. But

fortunately doped nanocrystals are sable at least

till 300 oC which we have measured for Mn doped

as well as Cu doped znSe (or znS) nanocrystals.

The lattice vibration with increase of temperature

does not harm the exciton recombination process

of these nanocrystals. Figure 5 shows the digital

image of Mn doped znSe showing bright emission

at different temperatures.

Photo-oxidation is another harmful

process to quench the emission of nanocrystals. In

presence of UV light and oxygen the nanocrystal

surface gets photo-oxidized very quickly and

hence undoped quantum dots are always kept

under Argon for their applications. As stated

above even oxidations states are created in doped

nanocrystals but their excitonic recombination

is not harmed and hence these would be useful

for many applications as the emission is not

susceptible to photo-oxidation.

Current Applications and Future Prospects:

As stated above doped nanocrystal

emitters whose intensity is as similar to undoped

nanocrystals can be useful for various applications

e.g. making light emitting devices, biological

labeling etc. These are free from heavy metal

cadmium and hence would be acceptable by

the community. Unfortunately these doped

nanocrystals do not have all color emission

and their higher excited state lifetime always

provide less emission in comparison to undoped

quantum dots. However, the field of this research

is just started and hope in near future the details

of synthesis, mechanism of origin of doped

nanocrystals, their various applicatiosn etc would

come out and would be helpful in various practical

applications.

Figure 5. Digital images of the reaction flask of Mn doped ZnSe at different reaction temperature. Excitation wavelength is 365 nm.



Experimental

Mn or Cu doped semiconductor (ZnS,

ZnSe, ZnCdS, ZnCdSe) nanocrystals are synthesized

following a generic synthetic method using dopant

oxides as dopant source.

materials. zinc stearate (zn(St)2, tech), zinc

undecylenate (zn(Un)2, 9�%), Octadecylamine

(ODA, 97%), �-Octadecene (ODE, tech.), Oleylamine

(OA, tech.,70%), Manganese acetate tetrahydrate

(Mn(OAc)2;�H

2O), 99%), Stearic acid (SA), Quinine

sulphate dehydrate dye and Sulfur (S) powder

were purchased from Aldrich. Selenium powder

(200 mesh, 99.99%) was purchased from Alfa-

Aesar. Cupric acetate monohydrate (Cu(OAc)2;H

2O),

has been purchased from Loba Chemie.

Tributylphoshphine (TBP, 97%) was purchased

from Spectrochem. Cadmium oxide (brown) was

purchased from Fluka. All these chemicals were

used without further purification.

metal oxide nanocrystals synthesis. Metal

oxide nanocrystals are synthesized by thermal

decomposition of respective metal carboxylates

in presence of fatty amines in a modified literature

method (Jana et. al. Chem. Mater. 200�, �6, 393�).

In a typical synthesis, 0.5 mmol of manganese

acetate and 5 ml oleylamine are loaded in a 25 ml

three necked flask, degassed by purging Argon

and heated to �50 oC. After annealing 30 min at

this temperature, the reaction was cooled to room

temperature and manganese oxide nanocrystals

are precipitated using methanol as non-solvent.

These oxide nanocrystals are purified by

washing with methanol and stored in chloroform

for reaction. XRD supports these manganese

oxides are Mn3O

� and their size varies (up to 20

nm) depending on the annealing time. Cu oxides

are prepared similarly from their carboxylate

(acetate) precursors decomposition.

synthesis of Doped Zns nanocrystals. For Mn

doped zinc sulfide nanocrystals first the host

znS nanocrystals were synthesized and Mn3O

�

solutions were injected during growth stage.

For znS nanocrystals synthesis, 0.� mmol of zinc

Stearate, zn(St)2 and �0 ml of ODE are loaded in a

50 ml three necked flask, degassed for �0 minutes

at �00 oC by purging with argon and then heated

to 300 oC. In a vial, 0.5 mmol S powder in � ml of

ODE was taken with 0.3 g of ODA under argon and

mixture was injected into the above reaction flask

at 300 oC. The temperature was reduced to 250oC

and � ml of Mn3O

� stock solution was injected. Then

the reaction temperature was again increased to

2�0 oC for znS growth. �.0 mmol zn(St)2 with 0.5

mmol SA in 5 ml of ODE were injected into it. The

mixture was annealed at 250 oC for �0 min and

cooled to room temperature. In case of copper

doped znS, after the sulfur injection the reaction

flask was cooled to ��0 oC and � ml of CuO

solution oleylamine was added drop wise into it.

The mixture was annealed at that temperature for

60 min.

Synthesis of other doped nanocrystals

are followed in similar method. Host nanocrystals

are synthesized following literature methods.

instrumentation:

UV-Vis and Photoluminescence

spectra were collected using Shimadzu UV 2550

spectrophotometer and Horiba Jobin Yvon

Fluromax-� spectroflurometer respectively.

TEM images were taken on a JEOL-JEM 20�0

electron microscopy using 200 kV electron source.

Specimens were prepared by dropping a drop



of purified nanocrystal in chloroform or water

on a carbon coated copper grid, and the grids

were dried in air. ICP was done by Perkin – Elmer

Optima 2�00 DV machine. Samples for ICP were

prepared using a method described elsewhere.

XRD of the doped sample was performed by

Bruker D� Advance powder diffractometer, using

Cu Kα (λ= �.5� Ǻ) as the incident radiation. EPR

measurement was done using a 9.5 GHz Bruker

ESP-300 spectrometer operated at X-band

frequency.

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BIAS ESTIMATION STRATEGIES

M.V.Bhaskarachary�, J.R.Pati2 and M.C.Adhikary3

�Integrated Test Range, Defence R&D Organization, Chandipur756025

Email: [email protected], Tel. No: 09�37297�2� 2 Balasore College of Engineering & Technology, Balasore 756060

Email: jnyana.pati9�@gmail.com, Tel. No: 09�37��5299 3 P.G. Department of Applied Physics and Ballistics, FM University, Balasore 7560�9

Email: [email protected], Tel. No: 09�3��200�7

Abstract

Bias estimation is a prerequisite to data fusion and processing before deploying

the Tracking instruments in a Missile Test Range for obtaining accurate measurements.

Various bias estimation strategies using Kalman Filtering techniques are explored in

this paper. The strategies mentioned can be adopted any type of problem with suitable

models.

1. introduction

In a Test Range various tracking instruments

deployed to track the airborne weapon in real

time have got different accuracies. Some of

these instruments like radars have fixed offsets

called biases with reference to true values or more

accurate sources. Bias is a constant offset in a

measurement by an instrument with reference to

a true value. Here the true value is generally track

Keywords: Bias, Filtering, Range, Azimuth, Elevation, Synchronization, Real time, Tracking, Simulation,

Modeling.

data obtained by an accurate measurement

source like Differential GPS system. Tracking

radar measures the position of an object in

space and gives Range, Azimuth, and Elevation

of the object including other parameters. These

measurements may be biased and the biases

are to be estimated prior to a real flight as a

part of calibration in dynamic conditions from

Contributed Paper



the data obtained during helicopter sorties.

These biases are assumed to be constant in

Azimuth, and Elevation. And the Range bias

may vary as a function of Range.

A bias is defined as systematic constant

or slowly variant error in all measurements. These

biases are mainly due to an incorrect sensor

calibration and signal propagation.

Bias = Measured value – True value

1.2 Kalman Filter

In statistics, the Kalman Filter [�] is a

mathematical method named after Rudolf E.

Kalman. Its purpose is to use measurements

that are observed over time that contain noise

(random variations) and other inaccuracies, and

produce values that tend to be closer to the true

values of the measurements and their associated

calculated values. The Kalman filter has many

applications in technology, and is an essential

part of the development of space and military

technology. Perhaps the most commonly

used type of very simple Kalman filter is the

phaselocked loop, which is now ubiquitous in

FM radios and most electronic communications

equipment. Extensions and generalizations to

the method have also been developed.

The Kalman filter produces estimates

of the true values of measurements and their

associated calculated values by predicting a

value, estimating the uncertainty of the predicted

value, and computing a weighted average of

the predicted value and the measured value.

The most weight is given to the value with the

least uncertainty. The estimates produced by the

method tend to be closer to the true values

than the original measurements because the

weighted average has a better estimated

uncertainty than either of the values that went

into the weighted average.

From a theoretical standpoint, the Kalman

filter is an algorithm for efficiently doing exact

inference in a linear dynamical system, which is a

Bayesian model similar to a hidden Markov model

but where the state space of the latent variables

is continuous and where all latent and observed

variables have a Gaussian distribution (often a

multivariate Gaussian distribution).

The Kalman filter is a recursive estimator.

This means that only the estimated state from the

previous time step and the current measurement

are needed to compute the estimate for the

current state. In contrast to batch estimation

techniques, no history of observations and/or

estimates is required. In what follows, the notation

xn|m

represents the estimate of x at time n given

observations up to, and including at time m .

The state of the filter is represented by two variables:

xk|k

, the a posteriori state estimate at time k given

observations up to and including at time k;

Pk|k

, the a posteriori error covariance matrix (a

measure of the estimated accuracy of the state

estimate).

The Kalman filter can be written as

a single equation, however it is most often

conceptualized as two distinct phases: Predict

and Update. The predict phase uses the state

estimate from the previous timestep to produce

an estimate of the state at the current timestep.

This predicted state estimate is also known as

the a priori state estimate because, although it

is an estimate of the state at the current timestep,

it does not include observation information

from the current timestep. In the update phase,



the current a priori prediction is combined with

current observation information to refine the

state estimate. This improved estimate is termed

the a posteriori state estimate.

Typically, the two phases alternate,

with the prediction advancing the state until

the next scheduled observation, and the update

incorporating the observation. However, this is

not necessary; if an observation is unavailable

for some reason, the update may be skipped and

multiple prediction steps performed. Likewise, if

multiple independent observations are available

at the same time, multiple update steps may be

performed (typically with different observation

matrices Hk).

Predict

Predicted (a priori) state estimate

xk|k -�

= FkX

k-�|k-� + B

ku

k

Predicted (a priori) estimate covariance

Pk|k -�

= FkX

k-�|k-� F

kT+ Q

k

Update

Innovation or measurement residual

yk

= zk

- Hk

xk|k-�

Innovation (or residual) covariance

Sk

= Hk

Pk|k-�

Hk

T +Rk

Optimal Kalman gain

Kk

= Pk|k-�

Hk

T Sk

-�

Updated (a posteriori) state estimate

Xk|k

= Xk|k-�

+ Kky

k

Updated (a posteriori) estimate covariance

Pk|k

= (I - KkH

k) + P

k|k-�

The formula for the updated estimate and

covariance above is only valid for theoptimal

Kalman gain.

invariants

If the model is accurate, and the values for x0|0

and P0|0 accurately reflect the distribution of the

initial state values, then the following invariants

are preserved: (all estimates have mean error

zero)

E [xk - x

k|k]

= E [x

k - x

k|k -�] = 0

E [yk ] = 0

Where E [ ε ] is the expected value of ε, and

covariance matrices accurately reflect the

covariance of estimates.

Pk|k

= cov (xk- x

k|k)

Pk|k-�

= cov (xk- x

k|k-�)

Sk|k

= cov (yk)

1.3 example

Consider a truck on perfectly frictionless,

infinitely long straight rails. Initially the truck is

stationary at position 0, but it is buffeted this way

and that by random acceleration. We measure

the position of the truck every t seconds, but

these measurements are imprecise; we want to

maintain a model of where the truck is and

what its velocity is. We show here how we derive

the model from which we create our Kalman

filter.

Since f, h, r and Q are constant, their

time indices are dropped. The position and velocity

of the truck is described by the linear state space

x

k =[ x ] x

Where x is the velocity, that is, the

derivative of position with respect to time.

We assume that between the (k − �)st

and kth timestep the truck undergoes a constant

acceleration of ak that is normally distributed, with

mean zero and standard deviation σa.



From Newton’s laws of motion we

conclude that

xk

= Fxk-�

+ Gak

Note that there is no Bu term since there

is no known control inputs,

where F = [ � ∆t ] and G =[ ∆t2

], so that

0 � ∆t

xk = Fx

k-1 + w

k

Where wk~ N(0, Q) and Q =GGT σ2 =[ ]

a

At each time step, a noisy measurement

of the true position of the truck is made. Let

us suppose the measurement noise vk is also

normally distributed, with mean 0 and standard

deviation σz.

zk = Hx

k + v

k

Where H = [1 0] and R = E [vk vT] = [σ2]

k z

We know the initial starting state of the truck with

perfect precision, so we initialize

x0|0

=[ 0 ] 0

and to tell the filter that we know the exact

position, we give it a zero covariance matrix:

P0|0

= [ 0 0 ] 0 0

If the initial position and velocity are

not known perfectly the covariance matrix

should be initialized with a suitably large number,

say L, on its diagonal.

P0|0

= [ L 0 ] 0 L

The filter will then prefer the information

from the first measurements over the information

already in the model.

2. Bias estimation strategies

Kalman Filtering is a technique for

filtering and prediction which had been used

extensively in many applications. The idea is to

utilize this technique for estimation of biases and

establish a profound mechanism to quantify

and correct the bias errors. The following three

strategies are explored.

2.1 strategy 1

Data obtained from an accurate

source from Differential GPS (DGPS) is

taken as a reference to estimate the biases

based on the differences with reference to

a common reference frame after making the

required transformations. The computations

are made in Cartesian reference frame. The

data obtained from DGPS primarily consisting

of Time, Latitude, Longitude and Altitude

of a flight vehicle which is converted in

to a Cartesian reference frame T�,X

�,Y

�,z

� (

Reference taken as point “O” say). Radar data

obtained consisting of Time, Range , Azimuth

and elevation which is converted to Cartesian

reference frame T2,X

2,Y

2,z

2 (Reference taken as

point “R” say). After proper time synchronization,

appropriate Kalman Filtering is used in both

the sets of data to remove the noise and

to compensate any modeling errors. After

filtering the data is transformed back to a

common reference point and R, A, E biases are

estimated. This estimation can be done in off line

after obtaining the track data from simulations

or from a real flight data. These bias corrections

can be applied in real flight situations after

proper validations.

∆t4 ∆t3

4 2 σ2

a∆t3

2 ∆t2



2.2 strategy 2

Another strategy is to augmentation

of state[2]. The bias vector is appended to

the state vector, and he bias dynamic equation

= 0 is appended to the original process dynamic

equation to form an augmented dynamic system.

A Kaman filter applied to the new system then

estimates the state of the original problem as

well as the bias terms. However, when the number

of bias terms is comparable to or larger than

the number of states of the original problem,

the implementation of the filter involves much

larger matrices, which may pose the numerical

conditioning difficulties and effect the accuracy

of bias estimation.

2.3 strategy 3

Another strategy is to estimate the biases

of a set of Radars R�, R

2…R

N by formulating

appropriate error models [3]. All these radar bias

estimation methods are based on processing

differences of measurements taken from pairs

of sensors and referred to the same aircraft. It is

important to notice that the first measure used

in the measurement pair needs to be extrapolated

(using the velocity estimation of the track to

which the two plots are associated with) to the

second measure timestamp. The three methods

are a) Bias estimation based on LSE estimator, b)

Bias estimation based on MSE estimator and c)

Bias estimation based on Extended Kalman Filter.

3. summary

Various strategies for estimating the biases are

mentioned in this paper. The first strategy is simple

to implement and the biases can be estimated in

offline by calibration trials before the actual flight.

Reducing the computational effort in real time,

the same can be implemented in real flight also

with appropriate logics. The second strategy

of State Augmentation [2] is more logical at

cost of computational complexities which can

be minimized by separate bias estimation with

reduced order kalman filter. The third strategy

requires more number of tracking sources

connected in a network with appropriate error

models [3]. The estimates obtained in all the

three strategies can be compared with simulated

data and methods can be adapted to various

applications.

references

[�] Kalman Filter Wikipedia [2] D Haessig, B Friedlan “SeparateBias Estimation with

ReducedOrder Kalman Filters” IEEE Transactions on Automatic Control, Vol �3 No.7, July �99�

[3] A.S.Jaramillo, J.A.B. Portas, J.R.Casar Corredera, J.I.Portillo Garcia “Online Bias Estimation of Secondary Radar Network for ATC” Universidad Politécnica de Madrid Despacho C3�5.�. ETSI de Telecomunicación Ciudad universitaria, Sno.2�0�0 Madrid, Spain.



AN INTRODUCTION TO SOME IMPORTANT FORCES ACTING ON A SPINNING PROJECTILE

PK Mahapatra

Scientist-F ( Retd),PXE, Chandipur

Abstract

When in flight, the main forces acting on a projectile are gravity, drag, and if present,

wind. Gravity imparts a downward acceleration on the projectile, causing it to drop

from the line of sight. Drag or the air resistance decelerates the projectile. Wind makes

the projectile deviate from its trajectory. During flight gravity, drag and the wind have

major impact on the path of the projectile, and must be accounted for when predicting

how the projectile will travel.

Drag opposes the motion but is not exactly opposite to the longitudinal axis of the

projectile. This give rise to yaw and introduces instability. Imparting spin is a method

to stabilise a projectile. But this introduces other impediments. Some of such important

impediments have been discussed in this short introductory presentation.

introduction

Generally, a body moving through the atmosphere

is affected by a variety of forces. Some of those

forces are mass forces, which apply at the center

of gravity of the body and depend on the body

mass and the mass distribution. A second group

of forces is called aerodynamic forces, resulting

from the interaction of the projectile with the

surrounding airflow.

A quite simple experimental photographic

technique which enables the visualization of

the flow of air in the vicinity of a moving body

produces a picture called a “shadowgraph”.

The first photograph shows a projectile traveling at

approximately approx. 850 m/s

Contributed Paper



At least three different shock waves can

be distinguished. The first and most intensive one

emerges from the projectile’s nose and is called

the Mach cone. A second shock wave originates

from the location of the cannelure, and the third

shock wave forms behind the projectile’s base.

Besides, a highly turbulent flow behind the base

can be seen. It is called the wake.

The flow type at the projectile’s surface

changes from a laminar boundary layer at

the forward region of the projectile, which is

characterized by parallel stream lines, into a

turbulent flow showing vortexes, beginning at the

cannelure.

For a projectile, moving slightly faster

than the speed of sound, one finds the following

significant differences: the Mach cone is still

present but no longer attached to the projectile’s

tip and the vertical angle of this cone has increased.

The wake is still visible,

forces and moments

The shadowgraphs have shown that the flowfield

in the vicinity of a projectile most generally

consists of laminar and turbulent regions. The

flowfield depends mostly on :

➢ the projectile’ velocity

➢ its shape, and

➢ the surface roughness.

The flowfield obviously changes

tremendously, as the velocity drops below the

speed of sound, which is about 3�0 m/s at standard

atmospheric conditions.

The mathematical equations, by means

of which the flowfield parameters (for example

pressure and flowfield velocity at each location)

might be determined are well known as the

Navier-Stokes equations. With the help of powerful

computers, numeric and practically useful

solutions to these equations have been found up

to now only for very specific configurations.

Because of these computational

restrictions, ballisticians all over the world

consider projectile motion in the atmosphere

by disregarding the specific characteristics of

but the boundary layer appears to be laminar

from the tip to the base, all along the projectile’

s surface.

Finally, for another projectile, moving at

subsonic speed, all shock waves are absent, and

what remains is slight turbulences behind the

projectile’s base.



Let F� be the resultant wind force (air

resistance) opposing the motion of a projectile

moving with velocity v and a yaw angle δ This

force seems to apply at the centre of pressure

CP of the wind force. The location of the center

of pressure depends on the flow field structure,

in other words, depending on whether the bullet

is in supersonic, transonic or subsonic flight. It

also depends on the projectile conditions and

the surface exposed to the force during the spin.

Since for all practical purposes the flight of the

projectile is considered by tracing the path of its

CG, we shall shift the force acting at CP to CG and

proceed further.

overturning moment

Introduce two equal and opposite forces fW

and

f2, (both equal to F

�) at the CG. These mutually

neutralize.

Now let us consider the two forces f� and

f2. It can be shown that this couple is a free vector,

which is called the aerodynamic moment of the

wind force or, for short, the overturning moment

mW

, or, the yawing moment.

We can proceed one step further and

split the force fW

, which applies at the CG, into

a force which is parallel but opposite to the

direction of movement of the CG plus a force,

which is perpendicular to this direction. The first

force is said to be the drag force fD or simply drag,

the other force is the cross-wind force. Thus

cross wind force is the component of the total

air resistance perpendicular to the trajectory, in

the plane of yaw. It introduces lateral shift for the

projectile.

The overturning moment mW

tends to

rotate the projectile about an axis, which goes

through the CG and which is perpendicular to the

plane of drag, the plane, formed by the velocity

vector v and the longitudinal axis of the projectile.

Obviously, the overturning moment tends to

tumble the projectile end over end.

If the CP is kept behind the CG by

introduction of fins, as in case of mortars, APFSDS

shots and missiles, overturning moment is

overcome. If, on the other hand, the CP is ahead

of the CG, as in case of artillery projectiles,

introduction of spin is the only way out.

Gyroscopic effect comes into play. This opposes

the overturning moment and tends to keep the

axis in the original direction.

side effects of gyroscopic effect

According to the laws of gyroscope, the action

of the projectile in seeking to overcome this

overturning moment must manifest itself in a

the flowfield and apply a simplified viewpoint:

the flowfield is characterized by the forces and

moments affecting the body.



precession of the projectile about the direction

of the force which creates the moment. Also,

the projectile having right handed spin, the

precessional revolution must be clock-wise as

viewed from the rear.

Generally, the wind force is the dominant

aerodynamic force. However, there are numerous

other smaller forces but we will consider the

magnus force and cushioning force, which turn

out to be very important for projectile stability

and also drift.

magnus force

A spinning object creates a kind of whirlpool of

rotating air about itself. On one side of the object,

the motion of the whirlpool will be in the same

direction as the wind stream that the object

is exposed to. On this side the velocity will be

increased. On the other side, the motion of the

whirlpool is in the opposite direction of the wind

stream and the velocity will be decreased. The

pressure in the air is reduced from atmospheric

pressure by an amount proportional to the square

of the velocity, so the pressure will be lower on

one side than the other causing an unbalanced

force at right angles to the wind.

With respect to the figure, we are looking

at a projectile from the rear spinning clockwise.

We additionally assume the presence of an angle

of yaw δ. The projectile’s longitudinal axis should

be inclined to the left. Thus, there is a pressure

difference, which results in a downward (only in

this diagram!) directed force, which is called the

magnus force fm

.

The Magnus effect has a significant role

in bullet stability because the Magnus force does

not act upon the bullet’s center of gravity, but

the center of pressure, affecting the yaw of the

bullet. If the centre of pressure is ahead of the

CG then Magnus force has a destabilising effect.

The following variables affect the magnitude of

gyroscopic drift:

• Projectile length: longer projectiles

experience more gyroscopic drift because

they produce more lateral “lift” for a given

yaw angle.

• Spin rate: faster spin rates will produce more

gyroscopic drift because the nose ends up

pointing farther to the side.

• Range, time of flight and trajectory height:

gyroscopic drift increases with all of these

variables.

cushioning force

The theory of cushioning force also depends on

the obliquity of the projectile. If the underside

is presented to the air stream, the air banks up

against this side, forming a sort of hard cushion.

The projectile tends to roll on this cushion because

of the friction imposed by it. This movement is to



the right in a projectile with right-handed spin. As

the projectile moves down the range it builds up

speed while moving to the right and the further

downrange it goes the faster it moves to the right

as it accumulates right-hand speed due to the

rolling motion on the cushion of air. This is also

known as Poisson’s effect.

spin damping moment

Skin friction at the projectile’s surface retards its

spinning motion. However, the angular velocity

of the rotating projectile is much less damped by

the spin damping moment than the translational

velocity, which is reduced due to the action of the

drag force.This is the reason why projectiles, which

are gyroscopically stable at the muzzle will remain

gyroscopically stable for the rest of their flight.

coriolis effect

Before concluding, we shall discuss one more effect

which affects long range projectiles. These effects

cause drift related to the spin of the Earth, known

as Coriolis drift. Coriolis drift can be up, down, left or

right. It is not an aerodynamic effect. It is a result of

flying from one point to another across the surface

of a rotating planet (Earth). The direction of Coriolis

drift depends on the firer’s and target’s location or

latitude on the planet Earth, and the azimuth of

firing. The magnitude of the drift depends on the

firing and target location, azimuth, and time of

flight. The Coriolis effect is at its maximum at the

poles and negligible at the equator of the Earth.

conclusion

Once a projectile is out of the gun it forces its way

through the atmosphere and thus is affected by

it. Some are inherent, like that of gravity. Some are

created because of its motion, like air resistance.

If the projectile’s axis coincides with the tangent

to the trajectory at the CG throughout the

trajectory from gun muzzle to the target, then

life would have been much simpler! There would

not be any requirement of fin or gyroscopic

stabilisation, there will not be any crosswind force,

no precession and no Magnus force. Of course

there will be Coriolis effect. No pure analytical

model has been developed till now to exactly

predict all the forces and their effects by taking

the projectile parameters and initial conditions

as input and pinpoint the arrival point before the

projectile arrives there.

references:

[�] How do bullets fly? by Ruprecht Nennstiel, Wiesbaden, Germany (www.nennstiel-ruprecht.de/ )

[2] Gene Slovers US Navy Pages – Exterior Ballistics �935, Chapter 9 (www.eugeneleeslover.com)

[3] en.wikipedia.org



THE IMPORTANCE OF PLASTIC DEFORMATION AND CYCLIC STRESS IN WEAPON DESIGN

G. C. Rout

Condensed Matter Physics Group, Dept. of Applied Physics and Ballistics,

F. M. University, Vyasa Vihar, Balasore - 7560�9.

Abstract

The weapons are made of special materials having the characteristics of high ductility,

high fatigue resistance and very high yield-stress with high strain hardening qualities.

This communication briefly reports the plastic deformation with respect to tensile and

shear stress of the materials. Further it discuses how cyclic stress induces fatigue in

the materials and emphasizes the importance of the endurance limit of the materials.

Finally it emphasizes the importance of the plastic deformation and fatigue in the

weapon design.

Key words: Plastic deformation, yield-strength, fatigue, endurance limit.

1. introduction

The weapon designer requires the basic

forces acting on the projectiles and guns and the

mechanics of the materials [�]. Before weapon

design one should know several special materials

that can support higher stresses. Here we present

stress-strain relations in section 2 and the plastic

deformation in section 3. The section � deals

with the failure criteria. We discuss the fatigue of

materials in section 5 and the endurance limit in

section 6 and finally the conclusion in section 7.

2. stress- strain relations

Before proceeding to examine the

weapon design practice, one should discuss

the fundamentals of the general state of stress

in materials. The stress defines the force acting

on unit surface area. The stress on the material

gives rise to the strain. Here the strain in the

material is defined as the change length of a part

over its initial length. We require a relationship

between stress and strain to evaluate the material

behaviour under a load. According to the Hooke’s

Contributed Paper



a metal or plastic? Whether it has a distinct yield-

strength? Is it very brittle or ductile? Accordingly

we have three criteria for the yield or failure of

weapon components. These criteria are the Von

Mises, Tresca and Coulomb [3]. The Von Mises

criterion is applicable for metals and it assumes the

maximum distortion energy required to change

the shape of the material causing the yielding. The

material has a distinct yield-strength. If σ�, σ

2, σ

3 be

the principal tensile stresses, the conditions are

(σ� - σ

2) 2 + (σ

2 - σ

3) 2 + (σ

3 - σ

�) 2 = 6τ 2

and τ = �.�55 (σy / 2) (�)

Where, σy and τ are the yield-strength in simple

tension and in pure shear respectively. τ and σy

can be found experimentally. The Tresca or the

maximum shear stress condition is used for the

material with great ductility. The condition for a

weapon component not to exhibit failure is

(σ� - σ

3) < σ

y and τ = σ

y / 2 (2)

The Mohr-Coulomb or maximum normal stress

criterion is applied to the brittle materials which

show no yielding point. The condition for no

failure in the material is

σ�, σ

2, σ

3 < σ

U (3)

i. e. all the principal stresses must be less than the

ultimate stress σU of the material.

The designer takes into account these

criteria, while designing the weapons. The

weapons are categorized by their uses as gun

(low angle, line-of-sight, direct fire), howitzers

(high angle, beyond line-of-sight, indirect fire)

or mortars (very high angle, short range, indirect

fire). There are several types of tube designs

encountered in service weapons: (i) the monobloc

tube is made from one piece of metal which is

not the most efficient, (ii) the jacketed tube which

consists of separate layers or jackets built up as a

composite structure. This type is most obsolete

now, and (iii) autofrettaging or self-jacketing in

which the quasi-two piece tube is formed by

inserting a liner into an otherwise monobloc tube.

This pressure containing tube allows for a more

resilient material for the projectile to ride against

and helps the wear of the tube.

5. cyclic stress and fatigue

Many components in civil and military

services are subject to fatigue. The fatigue is the

term used for a mechanical part that undergoes

cyclic loading and fails suddenly. A part that is

subject to fatigue failure has been subjected to

many small loads that stresses the components

below the yield strength. Damage begins to

accumulate through various mechanisms. A simple

example of fatigue is where you take a metal

paper clip and bend it 900. After this first bend,

the paper clip is still in one piece and the ultimate

yield-strength of the material is not exceeded. If

one repeats this multiple times with the same

paper clip, it will eventually break. This failure can

occur even without yielding the material.

A projectile usually undergoes one

cycle of loading and so fatigue is normally not

an issue. Gun tubes undergo thousands of cycles

and fatigue is a major consideration in their

design. The weapon design practice is to ensure

that a weapon shots out, before it fatigues out.

law, the strain is proportional to stress. In ordinary

materials, the tensile stress will reach some

critical value of stress (σ0), called the tensile yield-

strength. When this stress is removed, a very small

permanent strain (usually 0.0� % to 0.02 %) still

remains. The stress-strain relation is linear below

the yield-strength. When the strain increases

too much beyond the yield point, the material

deforms permanently up to a maximum stress

(σmax

). This permanent deformation is called the

plastic deformation. The process whereby the

plastic deformation increases the yield-strength

is called the strain hardening [�]. The plastically

deformed materials with high strength of the strain

hardening are the important criteria for selecting

the material as gun material. A specialized steel is

more suitable as weapon material.

3. Plastic deformation of materials

If a pure copper rod is twisted, it at first

behaves elastically i.e. the shear strain increases

linearly up to the shear yield-strength (τ0 ∼ 6000

psi) of copper. If the copper rod is twisted too

much, it deforms permanently. This permanent

deformation is called the plastic deformation of

copper metal. It should be noted that the volume

remains constant during the plastic deformation.

Sometimes the original rod is capable of a large

plastic deformation. This shows the ductile nature

of the material. The maximum shear strain (γmax

)

is a measure of the ductility of the material. The

ductility of copper is 2 and the corresponding

shear yield-strength rises from τ0 = 6000 psi in

the elastic region to τmax

= 30,000 psi in the plastic

deformation region. The process whereby the

plastic deformation increases the yield-strength is

called the strain hardening. The copper rod begins

to show fracture at the shear yield-strength of τmax

.

We note here that it is necessary as

exactly as possible to know the nature of copper.

The copper with a slightly different composition,

a different history or copper which has been

mechanically deformed will behave differently.

The pure copper is conveniently used as projectile

material for a shear stress of 25,000 psi at a shear

strain of 0.9. In contrast to copper, the window glass

or a piece of chalk exhibits only elastic behaviour,

but not the plastic behaviour. They are known as

brittle materials that can not be considered as the

weapon grade materials.

The tensile test on the copper shows that

the tensile stress increases linearly with strain in

the elastic region up to a tensile yield-strength (σ0

= �0,000 psi) corresponding to the tensile strain

of 0.0�. On further increasing the strain, the plastic

deformation begins in copper up to the fracture

print with plastic yield-point of σmax

= 35,000

psi at a strain of ε = 0.5. Beyond this strain the

specimen exhibits necking showing the plastic

instability. Hence it is convenient to work with

pure copper as a weapon grade material with a

yield-strength of 30,000 psi at strain ε = 0.�5. It is

more convenient to work with the real stress (σr)

and real strain (εr) in dealing with large strains. The

empirical expression σr = Kε

rn represents plastic

deformation region of the ductile materials. K and

n are constants and n is called the strain hardening

exponent. Certain materials can be stretched to

�000% without fracture. This behaviour of the

material is called the superplasticity.

4. failure criteria

Before the design of the weapon

components, we have to determine the

characteristics of the materials [�, 2]. Will we use



a metal or plastic? Whether it has a distinct yield-

strength? Is it very brittle or ductile? Accordingly

we have three criteria for the yield or failure of

weapon components. These criteria are the Von

Mises, Tresca and Coulomb [3]. The Von Mises

criterion is applicable for metals and it assumes the

maximum distortion energy required to change

the shape of the material causing the yielding. The

material has a distinct yield-strength. If σ�, σ

2, σ

3 be

the principal tensile stresses, the conditions are

(σ� - σ

2) 2 + (σ

2 - σ

3) 2 + (σ

3 - σ

�) 2 = 6τ 2

and τ = �.�55 (σy / 2) (�)

Where, σy and τ are the yield-strength in simple

tension and in pure shear respectively. τ and σy

can be found experimentally. The Tresca or the

maximum shear stress condition is used for the

material with great ductility. The condition for a

weapon component not to exhibit failure is

(σ� - σ

3) < σ

y and τ = σ

y / 2 (2)

The Mohr-Coulomb or maximum normal stress

criterion is applied to the brittle materials which

show no yielding point. The condition for no

failure in the material is

σ�, σ

2, σ

3 < σ

U (3)

i. e. all the principal stresses must be less than the

ultimate stress σU of the material.

The designer takes into account these

criteria, while designing the weapons. The

weapons are categorized by their uses as gun

(low angle, line-of-sight, direct fire), howitzers

(high angle, beyond line-of-sight, indirect fire)

or mortars (very high angle, short range, indirect

fire). There are several types of tube designs

encountered in service weapons: (i) the monobloc

tube is made from one piece of metal which is

not the most efficient, (ii) the jacketed tube which

consists of separate layers or jackets built up as a

composite structure. This type is most obsolete

now, and (iii) autofrettaging or self-jacketing in

which the quasi-two piece tube is formed by

inserting a liner into an otherwise monobloc tube.

This pressure containing tube allows for a more

resilient material for the projectile to ride against

and helps the wear of the tube.

5. cyclic stress and fatigue

Many components in civil and military

services are subject to fatigue. The fatigue is the

term used for a mechanical part that undergoes

cyclic loading and fails suddenly. A part that is

subject to fatigue failure has been subjected to

many small loads that stresses the components

below the yield strength. Damage begins to

accumulate through various mechanisms. A simple

example of fatigue is where you take a metal

paper clip and bend it 900. After this first bend,

the paper clip is still in one piece and the ultimate

yield-strength of the material is not exceeded. If

one repeats this multiple times with the same

paper clip, it will eventually break. This failure can

occur even without yielding the material.

A projectile usually undergoes one

cycle of loading and so fatigue is normally not

an issue. Gun tubes undergo thousands of cycles

and fatigue is a major consideration in their

design. The weapon design practice is to ensure

that a weapon shots out, before it fatigues out.

law, the strain is proportional to stress. In ordinary

materials, the tensile stress will reach some

critical value of stress (σ0), called the tensile yield-

strength. When this stress is removed, a very small

permanent strain (usually 0.0� % to 0.02 %) still

remains. The stress-strain relation is linear below

the yield-strength. When the strain increases

too much beyond the yield point, the material

deforms permanently up to a maximum stress

(σmax

). This permanent deformation is called the

plastic deformation. The process whereby the

plastic deformation increases the yield-strength

is called the strain hardening [�]. The plastically

deformed materials with high strength of the strain

hardening are the important criteria for selecting

the material as gun material. A specialized steel is

more suitable as weapon material.

3. Plastic deformation of materials

If a pure copper rod is twisted, it at first

behaves elastically i.e. the shear strain increases

linearly up to the shear yield-strength (τ0 ∼ 6000

psi) of copper. If the copper rod is twisted too

much, it deforms permanently. This permanent

deformation is called the plastic deformation of

copper metal. It should be noted that the volume

remains constant during the plastic deformation.

Sometimes the original rod is capable of a large

plastic deformation. This shows the ductile nature

of the material. The maximum shear strain (γmax

)

is a measure of the ductility of the material. The

ductility of copper is 2 and the corresponding

shear yield-strength rises from τ0 = 6000 psi in

the elastic region to τmax

= 30,000 psi in the plastic

deformation region. The process whereby the

plastic deformation increases the yield-strength is

called the strain hardening. The copper rod begins

to show fracture at the shear yield-strength of τmax

.

We note here that it is necessary as

exactly as possible to know the nature of copper.

The copper with a slightly different composition,

a different history or copper which has been

mechanically deformed will behave differently.

The pure copper is conveniently used as projectile

material for a shear stress of 25,000 psi at a shear

strain of 0.9. In contrast to copper, the window glass

or a piece of chalk exhibits only elastic behaviour,

but not the plastic behaviour. They are known as

brittle materials that can not be considered as the

weapon grade materials.

The tensile test on the copper shows that

the tensile stress increases linearly with strain in

the elastic region up to a tensile yield-strength (σ0

= �0,000 psi) corresponding to the tensile strain

of 0.0�. On further increasing the strain, the plastic

deformation begins in copper up to the fracture

print with plastic yield-point of σmax

= 35,000

psi at a strain of ε = 0.5. Beyond this strain the

specimen exhibits necking showing the plastic

instability. Hence it is convenient to work with

pure copper as a weapon grade material with a

yield-strength of 30,000 psi at strain ε = 0.�5. It is

more convenient to work with the real stress (σr)

and real strain (εr) in dealing with large strains. The

empirical expression σr = Kε

rn represents plastic

deformation region of the ductile materials. K and

n are constants and n is called the strain hardening

exponent. Certain materials can be stretched to

�000% without fracture. This behaviour of the

material is called the superplasticity.

4. failure criteria

Before the design of the weapon

components, we have to determine the

characteristics of the materials [�, 2]. Will we use



In other words, the weapon becomes inaccurate

because of wearing away of the rifling or the bore

well before it fails in sudden manner because of

fatigue. The maintenance crew determines this

by periodically checking the internal condition

of the bore of the weapon. If the bore has been

worn away sufficiently, the tube is condemned.

The condemnation occurs after a certain large

number of rounds have been fired. The weapon

designer limits the number of firings keeping in

eye with the fatigue life of the weapon.

6. endurance

The endurance of a material is the

ability of the material to survive multiple cycles

of loading. This ability of the material can be

described graphically by S – N diagram. The S – N

diagram plots the allowable stress (S) in psi in

the material against the number of cycles (N)

required by the designer [�, 5]. For example, if the

designer requires �0,000 cycles for a particular

design using AISI �3�0 steel, it will be necessary

to keep the stress below approximately 3�,000

psi. Some materials show endurance limit, i. e.

after a certain large number of cycles, the stress

(S) of the material stops decreasing and reaches

a limiting value. The material can withstand an

infinite number of load cycles, if operated below

this endurance stress limit. The endurance limit

of this AISI �3�0 steel is around 2�,000 psi. The

tensile stress of different specialized steel is

given in table – I. A rough rule for stress (S) is

σ0 / � < S < σ

0 / � for �0� cycles. The aliminium

is notorious in a sense that it has no endurance

limit i. e. its stress continues to decrease.

Aluminium components always have a finite

fatigue life expectancy.

Table–I Tensile yield-strength (σ0) of special iron

Materials σ0 (in thousand psi)

Gray case iron 20

Pearlite malleable cast iron �5

AISI �020 steel 35 – �0

AISI �095 steel (hardened) �00 – ��0

AISI �3�0 annealed alloy steel 65 – 70

AISI �390 fully hardened alloy steel �30 – 22�

Marraging (300) steel 290

Piano wire 350 – 500

Note: - AISI �020 stands for American Iron and Steel

Institute with the �020 for a code specifying the

alloy components of steel and psi is abbreviation

of pound/ square inch.

There are many contributing factors to

the endurance of a weapon component. They

include the material part of the weapon, the

number of loading cycles and the stress level of

each load cycle. The other factors are the rate of

loading, rate of load reversal and the surface finish

of the components [6, 7]. The load that can not be

exceeded by one cycle is defined as,

Sn = S CR C

G C

S (�)

Here S is the stress in psi read from the

S – N diagram for the desired number of cycles,

CR is the factor for reliability required in the

design, CG is the factor for the rapidity of the

load reversal and CS is the factor for the surface

finish. These factors effectively reduce the

allowable stress in the part of the weapon (they

all should be ≤ �). For example, for a 70 mm gun

made of AISI �020 steel working at pressure

�3,000 psi, the typical parameters are CR = 0.93,

CG = 0.95, CS = 0.99.



7. conclusion

The propellant charge and the projectile

combination apply the maximum stress to

the weapon. These pressures are applied over

and over again as the weapon tube is cycled

with each shot fired. Hence the designer has to

predict the fatigue failure of the design. Many

of the concepts discussed above are applicable

to the design of the gun tube. The idea of safety

margin is essential in the design of the gun tube.

The gun tube must remain serviceable for many

cycles at stress levels very much comparable to

the fired projectiles.

references

[�] Ruoff A. L., Introduction to Material Science, (Prentice Hall of India.)

[2] Carlucci D. E., and Jacobson S. S., Ballistics: Theory and Design of Guns and Ammunition, (CRC Press, New York, 200�)

[3] Elam C. F., Distortion of Metal Crystals (Oxford Press, New York, �935)

[�] Bishop T., Fatigue and the Comet Disasters, Metal Progress, 67 (�955)77

[5] Sines G. and Waisman J. L., Metal Fatigue, (Mc Graw Hill, New York. �955)

[6] Deutschman A. D., Michel W. J., and Wilson C. E., Machine Design, Theory and Practice (Mac millan Publishing Company, New York, �975)

[7] Norton R. L., Machine Design, An Integrated Approach, (Pearson – Prentice Hall, New York, 2006)



HIGH-SPEED IMAGING IN BALLISTICS TEST AND EVALUATION

T K Biswal and M C Adhikary *

320,Ballistics Centre,Proof & Experimental Establishment, Channdipur,Balasore-756 025

*Department of Applied Physics & Ballistics, F. M. University, Balasore

ABSTRACT

High-speed imaging plays a major role in a Test Range where the direct access is

possible through imaging in order to understand a dynamic process thoroughly and

both qualitative and quantitative data are obtained thereafter through necessary

image processing and analysis. During ballistic test & evaluation process lots of physical

events are visualized after post analysis to have a better understanding of the whole

process. Though there is a maturity in the development of high-speed imaging devices,

but now there is a trend to evolve new methodologies to meet various goals in different

fields of science and technology. This paper depicts some of the methodologies applied

to the field of experimental ballistics in recent past.

1.introDUction

Performance evaluation of any armament store

by dynamic firing is the ultimate acceptance

criteria before its issue to users. At the same time

dynamic firing data is crucial for design validation

and optimization during the development phase.

Laboratory testing and simulation studies, many

a times, do not represent the true performance as

in actual condition. It is also difficult to simulate

the actual condition in the laboratory due to the

magnitude of firing stress and environmental

effect. Hence, dynamic test and evaluation is of

paramount importance both from the designers

and users point of view. To mention some of the

techniques� evolved during recent years, this

paper primarily focuses three different aspects

of test and evaluation methodologies pertaining

to performance of �0mm proximity fuze within

a close vicinity of an aerial target, estimation of

rapid rate of fire of AK630 weapon and attitude of

a �0mm AP shot before its impact on armor.

2. DeVeloPment of methoDoloGies

Recent developments in conventional armaments

focus more on pin-pointed accuracy, rate of fire and

reliability of the product for absolute performance.

Appropriate technique to evaluate the product

becomes a challenge to range technologists due

to variety type of stores and its intended use. Since

no single technique or methodology can meet

the evaluation requirement, there is a need to

develop methodologies for deriving performance

parameters from case to case basis. Some of the

methodologies are presented in subsequent

paragraphs.

2.1 spatial information of 40mm Proximity fuze

functioning against low flying target & study of

miss Distance of non-functioning ones

Measurement of miss distance2 is a vital

parameter for the fuze designer to know the

performance of ammunitions/warhead in

the close vicinity of intended target. Spatial

measurement accuracy of this parameter is very

important to judge ammunitions lethality and its

defeating capabilities. In the evaluation process

of fuze ammunitions, it is mandatory to know

about miss distance of the fuze-based projectile

when it fails to function with respect to some

aerial target.

2.1.1 methodology

The missile target (MT) is erected at 5m height

with respect to seabed and downrange �000m

along the line of fire. It simulates a low flying

missile flying at �000m altitude. It is an extended

target of cylindrical shape with 0.2m radius,

5.0m length and made of aluminum alloy sheet.

Proper distance is maintained between the

target and gun by use of distometer/laser range

finder and the line of fire is chosen considering

the range safety in to account. MT is erected

in a horizontal way such that its body axis and

gun axis lie in a vertical plane. DGPS is used

to measure the altitude of target and that of

camera location so that camera can be adjusted

to match its axis to that of MT and both axes

lie in one horizontal straight line. Measurement

accuracy down to 0.0�m is achieved in this DGPS.

It helps to know the exact separation between

camera and target and also to ascertain both

are at same height. High-speed digital CMOS

camera, Speed Cam Visario, is used where a

maximum resolution of �536x�02� pixel is

achieved at �000pps. Its sensor has got square

pixel of size ��µm x��µm.Image acquisition is

performed through an external trigger, a flash-

trigger, that picks up muzzle flash of the gun

during firing and initiates image acquisition.

This trigger time is considered as reference time

t0 at which projectile leaves the muzzle. Camera

records the event in the post-trigger mode to

facilitate determining time to burst of fuze

functioning over MT which is obtained through

off-line video analysis. In a series of functioning

rounds, burst time is determined for each round

and then mean burst time is calculated. This is

probable because in a firing series, parameters

like charge mass, charge temperature, gun

elevation etc are maintained constant through

out. Minimum distance of the projectile with

respect to MT needs to be calculated during

flight for miss distance calculation. Ideally in

�0mm proximity ammunitions, shell is designed

to function within 3m radius with respect to

MT body axis. So a field-of-view (FOV) of more

than 3.0m radius around MT longitudinal axis is

chosen using suitable optics.

Contributed Paper



HIGH-SPEED IMAGING IN BALLISTICS TEST AND EVALUATION

T K Biswal and M C Adhikary *

320,Ballistics Centre,Proof & Experimental Establishment, Channdipur,Balasore-756 025

*Department of Applied Physics & Ballistics, F. M. University, Balasore

ABSTRACT

High-speed imaging plays a major role in a Test Range where the direct access is

possible through imaging in order to understand a dynamic process thoroughly and

both qualitative and quantitative data are obtained thereafter through necessary

image processing and analysis. During ballistic test & evaluation process lots of physical

events are visualized after post analysis to have a better understanding of the whole

process. Though there is a maturity in the development of high-speed imaging devices,

but now there is a trend to evolve new methodologies to meet various goals in different

fields of science and technology. This paper depicts some of the methodologies applied

to the field of experimental ballistics in recent past.

1.introDUction

Performance evaluation of any armament store

by dynamic firing is the ultimate acceptance

criteria before its issue to users. At the same time

dynamic firing data is crucial for design validation

and optimization during the development phase.

Laboratory testing and simulation studies, many

a times, do not represent the true performance as

in actual condition. It is also difficult to simulate

the actual condition in the laboratory due to the

magnitude of firing stress and environmental

effect. Hence, dynamic test and evaluation is of

paramount importance both from the designers

and users point of view. To mention some of the

techniques� evolved during recent years, this

paper primarily focuses three different aspects

of test and evaluation methodologies pertaining

to performance of �0mm proximity fuze within

a close vicinity of an aerial target, estimation of

rapid rate of fire of AK630 weapon and attitude of

a �0mm AP shot before its impact on armor.

2. DeVeloPment of methoDoloGies

Recent developments in conventional armaments

focus more on pin-pointed accuracy, rate of fire and

reliability of the product for absolute performance.

Appropriate technique to evaluate the product

becomes a challenge to range technologists due

to variety type of stores and its intended use. Since

no single technique or methodology can meet

the evaluation requirement, there is a need to

develop methodologies for deriving performance

parameters from case to case basis. Some of the

methodologies are presented in subsequent

paragraphs.

2.1 spatial information of 40mm Proximity fuze

functioning against low flying target & study of

miss Distance of non-functioning ones

Measurement of miss distance2 is a vital

parameter for the fuze designer to know the

performance of ammunitions/warhead in

the close vicinity of intended target. Spatial

measurement accuracy of this parameter is very

important to judge ammunitions lethality and its

defeating capabilities. In the evaluation process

of fuze ammunitions, it is mandatory to know

about miss distance of the fuze-based projectile

when it fails to function with respect to some

aerial target.

2.1.1 methodology

The missile target (MT) is erected at 5m height

with respect to seabed and downrange �000m

along the line of fire. It simulates a low flying

missile flying at �000m altitude. It is an extended

target of cylindrical shape with 0.2m radius,

5.0m length and made of aluminum alloy sheet.

Proper distance is maintained between the

target and gun by use of distometer/laser range

finder and the line of fire is chosen considering

the range safety in to account. MT is erected

in a horizontal way such that its body axis and

gun axis lie in a vertical plane. DGPS is used

to measure the altitude of target and that of

camera location so that camera can be adjusted

to match its axis to that of MT and both axes

lie in one horizontal straight line. Measurement

accuracy down to 0.0�m is achieved in this DGPS.

It helps to know the exact separation between

camera and target and also to ascertain both

are at same height. High-speed digital CMOS

camera, Speed Cam Visario, is used where a

maximum resolution of �536x�02� pixel is

achieved at �000pps. Its sensor has got square

pixel of size ��µm x��µm.Image acquisition is

performed through an external trigger, a flash-

trigger, that picks up muzzle flash of the gun

during firing and initiates image acquisition.

This trigger time is considered as reference time

t0 at which projectile leaves the muzzle. Camera

records the event in the post-trigger mode to

facilitate determining time to burst of fuze

functioning over MT which is obtained through

off-line video analysis. In a series of functioning

rounds, burst time is determined for each round

and then mean burst time is calculated. This is

probable because in a firing series, parameters

like charge mass, charge temperature, gun

elevation etc are maintained constant through

out. Minimum distance of the projectile with

respect to MT needs to be calculated during

flight for miss distance calculation. Ideally in

�0mm proximity ammunitions, shell is designed

to function within 3m radius with respect to

MT body axis. So a field-of-view (FOV) of more

than 3.0m radius around MT longitudinal axis is

chosen using suitable optics.

Contributed Paper



2.1.2 experimental set-up & observations

The experimental lay out is shown in Fig.�..

Burst time is calculated for both shells and mean

time to burst is found out (typically in the order

of 976ms). The functioning of the two rounds

is affirmed well within three meter radius with

respect to MT. Subsequently two inert shells

are fired which simulate non-functioning ones.

These shells are also captured in flight. Separation

between MT center and the shell at 976ms from

reference time t0 is calculated from offline image

analysis and found out to be 0.37�m in one case

as shown in Fig.3.

C1 – in-line high-speed digital camera; C2 –range

camera; PC – camera control computer; T- flash

trigger; MT- missile target

Fig.� Schematic set up of experimental lay out

The in-line high-speed digital camera C� and

MT are separated by �000m and a telephoto lens

of �00mm focal length is used to have a spatial

resolution of �3mm/pixel in the object plane.

It ensures a 3x3 pixels image point of �0mm

proximity fuze at the target plane that can be

well resolved. To ascertain that shell is functioning

within the miss distance zone of the target, one

conventional camera C2, called as range camera, is

placed at right angle to MT and also maintaining

co-planarity to have equal height with respect

to MT. In case of functioning, the co-ordinates of

point of functioning is determined from both C�

and C2 data which read two orthogonal planes of

functioning.

Initially two fuze shells are fired to

function over MT that is confirmed by range

camera C2.Orthogonal views of inline and range

camera are shown in Fig. 2.

(a)

(b)

Fig. 2. Functioning of fuze (a) Perpendicular view

by C2 (b) In-line view by C�

Fig. 3 Measurement of miss distance with respect

to MT center

2.2 Determination of rate of fire of aK630

naval Weapon

AK-630 weapon of Russian origin has six barrels of

30mm caliber and determination of its high rate

of fire is crucial for its acceptance.

2.2.1. methodology

Rate of fire of the order �500 rounds/min has

been determined by an innovative layout by firing

a salvo of 30 rounds on to a witness target and

simultaneously recording target hit points by a

conventional video camera. The cumulative impact

on the target is calculated over time through

frame by frame analysis leading to estimation of

rate of fire. The same has also been attempted by

acoustics method and the results are in very close

agreement and reproducible.

2.2.2. experimental set up & observations

One witnessing target; a ply board of size

2.5mX2.5m, is erected at �00m downrange from

muzzle in the transverse plane with respect to the

line of fire. Conventional video camera is placed

adjacent to the gun to image the witnessing target

and to find out the number of shots crossing the

very target plane over time from their impacts on

target. Schematic set up for rate of fire studies of

AK-630 weapon is shown in Fig.�.

Here an IT ½” CCD camera is used with an

objective lens of focal length ��0mm. It covers a

field of view of 3.5mX2.66 m in the target plane.

Its sensor has got a resolution of 6�0 x ��0 pixels

which corresponds to 5mm resolution in the

target plane. Camera is powered form a camera

control unit (CCU) which is connected to a PC for

display and image analysis. Camera is positioned

on a platform to match with the line of fire and

its image center coincides with the witnessing

target center. The main aim is to look at the cluster

of impacts from a right angle position. Passive

imaging is incorporated in the total process and

due care is taken to image impact points. The

impact points are well defined and accounted for

its quanta unless otherwise there is a complete

superimposition of one above the other.

T

C

GUN

PC

CCU

C-camera, CCU-camera control unit, T-witnessing target

Fig.� Schematic set-up for recording Rate of Fire of weapon

(a)

(b)

Fig.5. a) Witnessing target showing impact points, b) graph showing impact points vs. time

Cluster of 30 munitions is fired in a salvo mode and

their impacts are shown on the witnessing target

in Fig.5.(a).Then offline analysis is performed to

obtain rate of fire which has been depicted in

Fig.5.(b). Here cumulative impacts over time is



2.1.2 experimental set-up & observations

The experimental lay out is shown in Fig.�..

Burst time is calculated for both shells and mean

time to burst is found out (typically in the order

of 976ms). The functioning of the two rounds

is affirmed well within three meter radius with

respect to MT. Subsequently two inert shells

are fired which simulate non-functioning ones.

These shells are also captured in flight. Separation

between MT center and the shell at 976ms from

reference time t0 is calculated from offline image

analysis and found out to be 0.37�m in one case

as shown in Fig.3.

C1 – in-line high-speed digital camera; C2 –range

camera; PC – camera control computer; T- flash

trigger; MT- missile target

Fig.� Schematic set up of experimental lay out

The in-line high-speed digital camera C� and

MT are separated by �000m and a telephoto lens

of �00mm focal length is used to have a spatial

resolution of �3mm/pixel in the object plane.

It ensures a 3x3 pixels image point of �0mm

proximity fuze at the target plane that can be

well resolved. To ascertain that shell is functioning

within the miss distance zone of the target, one

conventional camera C2, called as range camera, is

placed at right angle to MT and also maintaining

co-planarity to have equal height with respect

to MT. In case of functioning, the co-ordinates of

point of functioning is determined from both C�

and C2 data which read two orthogonal planes of

functioning.

Initially two fuze shells are fired to

function over MT that is confirmed by range

camera C2.Orthogonal views of inline and range

camera are shown in Fig. 2.

(a)

(b)

Fig. 2. Functioning of fuze (a) Perpendicular view

by C2 (b) In-line view by C�

Fig. 3 Measurement of miss distance with respect

to MT center

2.2 Determination of rate of fire of aK630

naval Weapon

AK-630 weapon of Russian origin has six barrels of

30mm caliber and determination of its high rate

of fire is crucial for its acceptance.

2.2.1. methodology

Rate of fire of the order �500 rounds/min has

been determined by an innovative layout by firing

a salvo of 30 rounds on to a witness target and

simultaneously recording target hit points by a

conventional video camera. The cumulative impact

on the target is calculated over time through

frame by frame analysis leading to estimation of

rate of fire. The same has also been attempted by

acoustics method and the results are in very close

agreement and reproducible.

2.2.2. experimental set up & observations

One witnessing target; a ply board of size

2.5mX2.5m, is erected at �00m downrange from

muzzle in the transverse plane with respect to the

line of fire. Conventional video camera is placed

adjacent to the gun to image the witnessing target

and to find out the number of shots crossing the

very target plane over time from their impacts on

target. Schematic set up for rate of fire studies of

AK-630 weapon is shown in Fig.�.

Here an IT ½” CCD camera is used with an

objective lens of focal length ��0mm. It covers a

field of view of 3.5mX2.66 m in the target plane.

Its sensor has got a resolution of 6�0 x ��0 pixels

which corresponds to 5mm resolution in the

target plane. Camera is powered form a camera

control unit (CCU) which is connected to a PC for

display and image analysis. Camera is positioned

on a platform to match with the line of fire and

its image center coincides with the witnessing

target center. The main aim is to look at the cluster

of impacts from a right angle position. Passive

imaging is incorporated in the total process and

due care is taken to image impact points. The

impact points are well defined and accounted for

its quanta unless otherwise there is a complete

superimposition of one above the other.

T

C

GUN

PC

CCU

C-camera, CCU-camera control unit, T-witnessing target

Fig.� Schematic set-up for recording Rate of Fire of weapon

(a)

(b)

Fig.5. a) Witnessing target showing impact points, b) graph showing impact points vs. time

Cluster of 30 munitions is fired in a salvo mode and

their impacts are shown on the witnessing target

in Fig.5.(a).Then offline analysis is performed to

obtain rate of fire which has been depicted in

Fig.5.(b). Here cumulative impacts over time is



plotted which shows a linear curve .It means a

uniform rate of fire is obtained in this weapon and

from its slope rate of fire is calculated. This is found

out to be ��52 shots/min and has got a very close

match with the one taken by normal acoustic

method.

2.3 Determination of attitude of Projectile

before impact on target

The attitude of a projectile at the point of impact

on armor affects the depth of penetration3.

Methodology for recording the attitude of the

projectile before its impact on target has been

developed by single shot capture of images

of the projectile in two orthogonal planes

simultaneously. It provides projectile orientation

both in vertical and horizontal planes leading

to measurement of both yaw and pitch angles

resulting its determination of attitude at the very

instance of space and time.

2.3.1 methodology

Imaging the projectile in two orthogonal planes

simultaneously, both horizontal and vertical,

determines both pitch and yaw angles from which

the attitude angle (angle of attack) is determined

as shown in Fig.6.

Let ∈ be the angle of attitude which is defined in 3-

D as shown above. It is resolved in two orthogonal

planes resulting є v and є

h which are yaw and

pitch angles respectively considering paraxial

firing as practiced during armor testing. Here the

angle of attitude є is expressed as

є = tan-� є (tan2 є v + tan 2 є

h )

Further tan є v and tan є

h are slopes of the

projectile image body axis captured in the vertical

and horizontal planes respectively.

2.3.2 experimental set up & observations

The mirror set up is positioned along the line

of fire such that longitudinal axis of the mirror

and the line of fire lie in the same vertical plane

of camera FOV. Here the projectile is allowed to

pass within a hollow cylindrical object containing

the very mirror at �5º with respect to the vertical

plane. Both direct and mirror images are recorded

simultaneously by a single ICCD camera. In this

case SVR II Ballistic Range Camera is used as

shown in Fig.7.

Fig. 6 Vector diagram for defining angle of attack є of the projectile in terms of vertical and horizontal angles є

v and є

h representing yaw and pitch

respectively

Gun Mirror

T

S

PC CAM

Fig. 7 Schematic set up for projectile attitude studies: T- optical trigger (sky screen); S-Xenon strobe



Optical trigger, a sky screen, placed under line

of fire and close to the mirror set up, is used as

external trigger for capture of shot image within

the camera FOV after incorporating appropriate

delay to the Xenon strobe, used as illuminating

source. The attitude of a �0mm AP shot before

impact on armor at 50m has been generated and

image is shown in Fig.�.

found to be less than 5º.This technique can be

used for different types of AP shots. During set up

perpendicularity of the camera to the line of fire

as well to the longitudinal axis of the mirror has

to be done very carefully. To achieve this, simple

pendulum can be used as a test image where

center of circles of both the direct and mirror

images should lie in one vertical line.

3. conclUsion

Techniques for estimation of miss distance

measurement of �0mm proximity fuze ,rate of

fire of AK630 weapon and attitude of a �0mm AP

shot have been established and are being used

currently in day to day trial activities.

acKnoWleDGement

The authors wish to express their sincere thanks

to Maj Gen Praveen Mathur , Director, Proof &

Experimental Establishment, Chandipur for his

encouragement and permission to publish this

paper.

Fig.� Orthogonal images of �0mm shot captured

in SVR II: Top-direct image (vertical plane) &

bottom-mirror image (horizontal plane)

In this case є v

and є h are found to be �.�º and

2.��º respectively and є is found out as 3.0�º.

Three shots were fired and in all the cases є was

references

[�] T K Biswal et al. “Dynamic test & evaluation methodologies for measurement of critical test parameters of armaments: case studies”, National Conf on Advances in Armament Technologies (NCAAT),ARDE, Pune Nov 200�.

[2] T.K. Biswal et al. “ Miss distance studies of �0mm proximity fuze with respect to anti-missile target using high-speed videography”, NACORT-2006, ITR (DRDO), Balasore.

[3] Manfred Held “Impact parameters of projectiles”, Propellants, Explosives, Pyrotechnics 2�,2��-2�6,�999.



MODELLING INTERIOR BALLISTIC PRESSURE GRADIENT PHENOMENON INSIDE GUN BARREL SYSTEM

KK Chanda , Smt NN Jenab and MK Dasc

a,bProof & Experimental Establishment, Chandipur, Balasore, Orissa-756 025ae-mail: [email protected]

be-mail: [email protected] of Physics, NC College, Jajpur Cuttack, Orissa

ce-mail: [email protected]

ABSTRACT

The science of interior ballistics is concerned with the converting some form of stored

energy into significant kinetic energy and transmitted to the projectile in gun systems,

or the work to be done against external forces. Interior ballistics processes are a very

complex phenomenon. Performance of a gun propellant is assessed through two

important parameters, pressure and velocity and carried out dynamic trials or actual

gun firings. The paper discusses with various modeling approach for pressure gradient

distribution phenomenon in the space behind the projectile and analyzed with the

availabled results of 30mm caliber cannon experimental firings. Lastly, performance of

a higher caliber weapon has been depicted as an example.

Keywords: gun system, ballistics, interior/internal ballistics, pressure gradient, projectile base pressure,

breech pressure, and gun propellant.

1. introDUction

1.1 THE SCIENCE OF GUN PROPULSION –

INTERIOR BALLISTICS

The science of interior ballistics is concerned with

the propulsion of a projectile along the tube of a

weapon by the gas pressure on the base of the

projectile, or, for rockets, by the backward exhaust

of the gas jet. Interior ballistics processes are a very

complex phenomenon. The basic interior ballistic

process may be considered as a heat engine, which

converts some form of stored energy (classically,

chemical energy of a solid propellant released

upon burning) into significant kinetic energy

of a launch package in a very short timeframe

and employing a launch system that occupies

limited space. The interior ballistic cycle includes

the entire phenomena-taking place during the

tube phases of gun firing. The kinetic energy

transmitted to the projectile in gun systems, or

the work to be done against external forces such

as the deformation force of the rotating band, is

produced by an exothermic and gas producing

reaction of solid propellants. Most processes of

warheads and ballistics – interior, exterior and

terminal – are very dependent on the use and

properties of energetic materials – propellants

and explosives – for their functioning. The very

nature of this highly dynamic launch environment

defines the fundamental problem for the gun

interior ballistician – managing the competition

between the production of gases from the

burning propellant and the volume to put them

in as the projectile moves down the bore, so as

to maximize the conversion of stored chemical

energy of the propellant to kinetic energy of the

projectile at muzzle exit, Figure �.

As shown in Figure 2, the challenge for more

performance thus translates into one of

increasing the area under the pressure vs. travel

curve without exceeding the maximum pressure

limits of the system, be they imposed by the gun

tube, the recoil system, or the projectile itself.

Produce the gases too rapidly and excessive

pressurization occurs; too slowly, the propellant

is not all burned and/or expansion of combustion

gases is limited, reducing the extraction of energy

to accelerate the projectile. Proper programming

of energy release, however, broadens the curve

and increases projectile kinetic energy at the

muzzle. This interesting process thus defines

the fundamental tasking to interior ballisticians

throughout history: increasing interior ballistic

performance by (i) increasing the total energy

available to the propulsion system and, equally

important, (ii) tailoring the release of this energy,

both temporarily and spatially, to maximize its

transfer to the projectile. Numerous contributions,

both experimental and theoretical, have addressed

this grand challenge for centuries.

1.2 INTERIOR BALLISTIC MODEL

The fundamental books and documents covering

the state of theoretical and practical knowledge

on propellant combustion, as a first approximation

recommend the burning law expressed as

exponential dependence on pressure

r = β • pα (�)

where α is the pressure index and β is the burning

rate constant of the propellant composition.

Above-mentioned equation is known as Saint

Robert’s equation. The burning rate law usually

approximates the burning rate of a propellant

where the value of pressure index is �. It means

Figure 1: Conversion of chemical energy stored in the propellant into kinetic energy in the projectile

Figure 2: Increasing the area under the pressure vs. travel curve without exceeding system pressure limits

Contributed Paper



MODELLING INTERIOR BALLISTIC PRESSURE GRADIENT PHENOMENON INSIDE GUN BARREL SYSTEM

KK Chanda , Smt NN Jenab and MK Dasc

a,bProof & Experimental Establishment, Chandipur, Balasore, Orissa-756 025ae-mail: [email protected]

be-mail: [email protected] of Physics, NC College, Jajpur Cuttack, Orissa

ce-mail: [email protected]

ABSTRACT

The science of interior ballistics is concerned with the converting some form of stored

energy into significant kinetic energy and transmitted to the projectile in gun systems,

or the work to be done against external forces. Interior ballistics processes are a very

complex phenomenon. Performance of a gun propellant is assessed through two

important parameters, pressure and velocity and carried out dynamic trials or actual

gun firings. The paper discusses with various modeling approach for pressure gradient

distribution phenomenon in the space behind the projectile and analyzed with the

availabled results of 30mm caliber cannon experimental firings. Lastly, performance of

a higher caliber weapon has been depicted as an example.

Keywords: gun system, ballistics, interior/internal ballistics, pressure gradient, projectile base pressure,

breech pressure, and gun propellant.

1. introDUction

1.1 THE SCIENCE OF GUN PROPULSION –

INTERIOR BALLISTICS

The science of interior ballistics is concerned with

the propulsion of a projectile along the tube of a

weapon by the gas pressure on the base of the

projectile, or, for rockets, by the backward exhaust

of the gas jet. Interior ballistics processes are a very

complex phenomenon. The basic interior ballistic

process may be considered as a heat engine, which

converts some form of stored energy (classically,

chemical energy of a solid propellant released

upon burning) into significant kinetic energy

of a launch package in a very short timeframe

and employing a launch system that occupies

limited space. The interior ballistic cycle includes

the entire phenomena-taking place during the

tube phases of gun firing. The kinetic energy

transmitted to the projectile in gun systems, or

the work to be done against external forces such

as the deformation force of the rotating band, is

produced by an exothermic and gas producing

reaction of solid propellants. Most processes of

warheads and ballistics – interior, exterior and

terminal – are very dependent on the use and

properties of energetic materials – propellants

and explosives – for their functioning. The very

nature of this highly dynamic launch environment

defines the fundamental problem for the gun

interior ballistician – managing the competition

between the production of gases from the

burning propellant and the volume to put them

in as the projectile moves down the bore, so as

to maximize the conversion of stored chemical

energy of the propellant to kinetic energy of the

projectile at muzzle exit, Figure �.

As shown in Figure 2, the challenge for more

performance thus translates into one of

increasing the area under the pressure vs. travel

curve without exceeding the maximum pressure

limits of the system, be they imposed by the gun

tube, the recoil system, or the projectile itself.

Produce the gases too rapidly and excessive

pressurization occurs; too slowly, the propellant

is not all burned and/or expansion of combustion

gases is limited, reducing the extraction of energy

to accelerate the projectile. Proper programming

of energy release, however, broadens the curve

and increases projectile kinetic energy at the

muzzle. This interesting process thus defines

the fundamental tasking to interior ballisticians

throughout history: increasing interior ballistic

performance by (i) increasing the total energy

available to the propulsion system and, equally

important, (ii) tailoring the release of this energy,

both temporarily and spatially, to maximize its

transfer to the projectile. Numerous contributions,

both experimental and theoretical, have addressed

this grand challenge for centuries.

1.2 INTERIOR BALLISTIC MODEL

The fundamental books and documents covering

the state of theoretical and practical knowledge

on propellant combustion, as a first approximation

recommend the burning law expressed as

exponential dependence on pressure

r = β • pα (�)

where α is the pressure index and β is the burning

rate constant of the propellant composition.

Above-mentioned equation is known as Saint

Robert’s equation. The burning rate law usually

approximates the burning rate of a propellant

where the value of pressure index is �. It means

Figure 1: Conversion of chemical energy stored in the propellant into kinetic energy in the projectile

Figure 2: Increasing the area under the pressure vs. travel curve without exceeding system pressure limits

Contributed Paper



that the burning rate and pressure rise in direct

proportion. Then the burning rate law is expressed

as linear dependence on pressure

r = r� • p , (2)

where it is assumed that value of coefficient r1 is

constant (for given type of propellant) regardless

of value of propellant gas pressure.

There are several interior ballistic models,

starting with classic models, up to so-called 3rd

generation models, which cover a wide area of

hypotheses, more or less realistic. In classic models,

the solution is entirely analytical, supposing

that all the physicochemical phenomena can be

modeled by polynomial or differential equations,

with known coefficients. For example, let us

consider the Muraour law (1st generation model-0

dimensional model) for burning rate of propellant

grain as a function of pressure:

v(p) = α • pn + b (3)

These models are no longer satisfied, while

the real behaviour of burning propellant is

far away from this hypothesis. The modern

models use numerical analysis and allow to skip

some analytical expressions, instead of using

experimental data like form function and burning

rate as input data in a source code, but this doesn’t

let us to avoid a number of simplifying hypotheses.

In the 2nd generation models, the pressure behind

projectile and the pressure on the breech are no

longer calculated based on the medium pressure

measured with the piezoelectric transducer. So, the

space between breechblock and the projectile is

divised into a number of finite elements (volumes)

and the pressure is a determined using CFD

algorithm. In 3rd generation models the biphasic

flow is considered, as the gases generation

process is not instantaneous, but there is, in the

first part of burning process, a mixture between

gases and unburned or partial burned propellant

grains (which is beyond the scope of discussion in

this paper).

Starting point of the model proposed is

the perspective on the propellant and burning

gases state. In both, closed vessel and gun barrel,

the dual phase (propellant-burning gases)

physical state can by defined at any moment of

time by some global parameters as pressure,

temperature, burned propellant mass fraction,

relative propellant density. The biphasic state may

be expressed by the equations bellow:

Eb = E

b ( P, Ψ , T, ∆ ) (�)

Eg= E

g ( P, Ψ , T, ∆ )

where: Eb - dual phase state in closed vessel; E

g -

dual phase state in gun barrel;

P - gases pressure; ψ - burned propellant mass

fraction; T - gases temperature;

∆ - relative propellant density (propellant mass

versus closed vessel or barrel internal volume ratio.

Further, for sake of simplicity and

assuming the hypothesis of closed vessel tests

data with similar heat loses as in gun barrel, we

could neglect the temperature evolution and its

effects. In this case, the equation (�) becomes:

Eb = E

b ( P, Ψ , T, ∆ ) (5)

Eg= E

g ( P, Ψ , T, ∆ )

Typical evolutions of gun barrel chamber pressure

and projectile velocity are shown in Figure 3.

Figure 3: Typical gun barrel pressure and projectile velocity time evolution

In the field of interior ballistics of guns, one of

the objectives of the studies carried out is the

development of numerical tools to understand

the behaviour of complex ammunition. Over

the past three decades, the field of interior

ballistic modelling has undergone a number of

major advances with the continual increase of

computing power. Before, lumped-parameter

models were used to perform large parametric

interior ballistics studies and they are still used for

most basic interior ballistics systems and charge

design studies.

2. mathematical moDellinG

When the projectile gains velocity, a pressure

gradient exists in the gun barrel due to hot gases,

acceleration of unburnt propellant and friction at

the bore surface. The ratio of breech pressure to

base pressure is a function of projectile velocity

and is given by Kent. If pressure at the projectile

base causing the motion is known, then velocity

time profile of the projectile can be obtained

by applying Newton’s equation of motion.

Kent’s Equation 6 has been used to compute

the instantaneous base pressures from actually

measured instantaneous breech pressure values.

The relationship between pd and p

s , comes as

hydrodynamic problem of the gun. The ratio of

pd

/ ps , derived by Kent is:

pd =� +

� ( ω )- � ( ω )2

+ ( �

+ � )( ω ) 2

+... (6)p

s 2 m

q 2�φ

� m

q �0φ

� 360φ

�2 m

q

where ω is the charge weight, mq is the projectile

weight and ϕ� is the ratio of specific heats or

losses coefficient. The value of ϕ� is calculated

from chemical composition of the propellant. The

value of ϕ� for LOVA propellant is �.26�6 and for

NQ/M propellant is �.250�.

During the movement of a projectile

inside a barrel is created a pressure gradient

between the barrel breech and the projectile base

due to the difference in velocities of propellant

gases at the breech and the projectile base, Figure

�. This pressure gradient belongs among factors

that significantly affect not only interior ballistic

calculations but also the design of projectiles. The

pressure gradient is usually characterized by the

ratio of the breech pressure pd and the projectile

base pressure ps.

Figure 4: Pressure gradient in the space behind a projectile p- ballistic pressure, v- velocity of projectile, l- projectile trajectory

Figure 5: Schematic of cylindrical cartridge chamber (lkom = l0) lkom - length of cartridge chamber, l0 - length of initial combustion volume

There are number of models describing the

pressure gradient but without any comparison

with experimental results. Most of the models

are relatively old and were created for ballistic

systems of lower performance, e.g. howitzers.

There is not any study analysing the suitability

of these models for modern medium calibre and



that the burning rate and pressure rise in direct

proportion. Then the burning rate law is expressed

as linear dependence on pressure

r = r� • p , (2)

where it is assumed that value of coefficient r1 is

constant (for given type of propellant) regardless

of value of propellant gas pressure.

There are several interior ballistic models,

starting with classic models, up to so-called 3rd

generation models, which cover a wide area of

hypotheses, more or less realistic. In classic models,

the solution is entirely analytical, supposing

that all the physicochemical phenomena can be

modeled by polynomial or differential equations,

with known coefficients. For example, let us

consider the Muraour law (1st generation model-0

dimensional model) for burning rate of propellant

grain as a function of pressure:

v(p) = α • pn + b (3)

These models are no longer satisfied, while

the real behaviour of burning propellant is

far away from this hypothesis. The modern

models use numerical analysis and allow to skip

some analytical expressions, instead of using

experimental data like form function and burning

rate as input data in a source code, but this doesn’t

let us to avoid a number of simplifying hypotheses.

In the 2nd generation models, the pressure behind

projectile and the pressure on the breech are no

longer calculated based on the medium pressure

measured with the piezoelectric transducer. So, the

space between breechblock and the projectile is

divised into a number of finite elements (volumes)

and the pressure is a determined using CFD

algorithm. In 3rd generation models the biphasic

flow is considered, as the gases generation

process is not instantaneous, but there is, in the

first part of burning process, a mixture between

gases and unburned or partial burned propellant

grains (which is beyond the scope of discussion in

this paper).

Starting point of the model proposed is

the perspective on the propellant and burning

gases state. In both, closed vessel and gun barrel,

the dual phase (propellant-burning gases)

physical state can by defined at any moment of

time by some global parameters as pressure,

temperature, burned propellant mass fraction,

relative propellant density. The biphasic state may

be expressed by the equations bellow:

Eb = E

b ( P, Ψ , T, ∆ ) (�)

Eg= E

g ( P, Ψ , T, ∆ )

where: Eb - dual phase state in closed vessel; E

g -

dual phase state in gun barrel;

P - gases pressure; ψ - burned propellant mass

fraction; T - gases temperature;

∆ - relative propellant density (propellant mass

versus closed vessel or barrel internal volume ratio.

Further, for sake of simplicity and

assuming the hypothesis of closed vessel tests

data with similar heat loses as in gun barrel, we

could neglect the temperature evolution and its

effects. In this case, the equation (�) becomes:

Eb = E

b ( P, Ψ , T, ∆ ) (5)

Eg= E

g ( P, Ψ , T, ∆ )

Typical evolutions of gun barrel chamber pressure

and projectile velocity are shown in Figure 3.

Figure 3: Typical gun barrel pressure and projectile velocity time evolution

In the field of interior ballistics of guns, one of

the objectives of the studies carried out is the

development of numerical tools to understand

the behaviour of complex ammunition. Over

the past three decades, the field of interior

ballistic modelling has undergone a number of

major advances with the continual increase of

computing power. Before, lumped-parameter

models were used to perform large parametric

interior ballistics studies and they are still used for

most basic interior ballistics systems and charge

design studies.

2. mathematical moDellinG

When the projectile gains velocity, a pressure

gradient exists in the gun barrel due to hot gases,

acceleration of unburnt propellant and friction at

the bore surface. The ratio of breech pressure to

base pressure is a function of projectile velocity

and is given by Kent. If pressure at the projectile

base causing the motion is known, then velocity

time profile of the projectile can be obtained

by applying Newton’s equation of motion.

Kent’s Equation 6 has been used to compute

the instantaneous base pressures from actually

measured instantaneous breech pressure values.

The relationship between pd and p

s , comes as

hydrodynamic problem of the gun. The ratio of

pd

/ ps , derived by Kent is:

pd =� +

� ( ω )- � ( ω )2

+ ( �

+ � )( ω ) 2

+... (6)p

s 2 m

q 2�φ

� m

q �0φ

� 360φ

�2 m

q

where ω is the charge weight, mq is the projectile

weight and ϕ� is the ratio of specific heats or

losses coefficient. The value of ϕ� is calculated

from chemical composition of the propellant. The

value of ϕ� for LOVA propellant is �.26�6 and for

NQ/M propellant is �.250�.

During the movement of a projectile

inside a barrel is created a pressure gradient

between the barrel breech and the projectile base

due to the difference in velocities of propellant

gases at the breech and the projectile base, Figure

�. This pressure gradient belongs among factors

that significantly affect not only interior ballistic

calculations but also the design of projectiles. The

pressure gradient is usually characterized by the

ratio of the breech pressure pd and the projectile

base pressure ps.

Figure 4: Pressure gradient in the space behind a projectile p- ballistic pressure, v- velocity of projectile, l- projectile trajectory

Figure 5: Schematic of cylindrical cartridge chamber (lkom = l0) lkom - length of cartridge chamber, l0 - length of initial combustion volume

There are number of models describing the

pressure gradient but without any comparison

with experimental results. Most of the models

are relatively old and were created for ballistic

systems of lower performance, e.g. howitzers.

There is not any study analysing the suitability

of these models for modern medium calibre and



high performance ballistic systems that still satisfy

the condition ω / mq < �.

2.1 moDels of PressUre GraDient

From the mentioned literatures the most

widespread models describing the pressure

gradient in the space behind a projectile were

chosen and were marked for needs of this paper as

model 1– 4. The fifth pressure distribution model

is used in the interior ballistic model described as

model STANAG �367.

Generally, it can be said, that basic element

of all analyzed models of pressure gradient is the

ratio , where: ω - mass of propellant charge, mq-

mass of the projectile.

2.1.1 moDel 1

This model is determined for ballistic systems with

a cylindrical cartridge chamber of the same area

of cross-section as area of cross-section of barrel,

Figure. 5.

In this model is the ratio of breech

pressure to the projectile base pressure expressed

as

(7)

trajectory. The dependency for common extent of

values ω / mq is shown in Figure. 7. From the Fig. 6

is clearly seen that according to the model 1 is the

pressure ratio pd / p

s directly proportional to the

ratio ω / mq.

ω2m

q

where: pd - breech pressure, p

s - projectile base

pressure, ω - mass of propellant charge, mq -

mass of projectile, φ� - losses coefficient (usually

between �.02 (howitzers and cannon) and �.�

(small arms �.05 – �.�).

In this model the ratio pd / p

s strongly

depends only on ratio ω / mq and remains constant

during the projectile movement inside the barrel,

i.e. the ratio is independent of the projectile

Figure 6: Dependency of pd / p

s on ratio ω / m

q and

φ1 = 1.1

Figure 7: Schematic of real cartridge chamber (lkom

≠ l

0)

2.1.2 moDel 2

A real cartridge chamber has usually bigger

diameter than the diameter of the barrel. This

model is based on the Model � and extended by

an effect of cartridge chamber shape. The effect of

the cartridge chamber shape is described by the

coefficient of cartridge chamber

shape , Figure 7.

The ratio of breech pressure pd to the projectile

base pressure ps is, in this model, described by

following empirical relation

(�)

where: χ ... coefficient of cartridge chamber shape,

k ... exponent (recommended value 0.3.

For calculation of exemplary courses

of pd / p

s were chosen typical extent of ratios ω /

mq from 0.2 to �.0, exponent k = 0.3 according to

recommendations from literature, and coefficient

φ1 = �.�. The obtained dependencies of p

d / p

s are

shown in Figure �.

The ratio pd / p

s is again independent of the projectile

trajectory and remains constant during the

projectile movement inside the barrel. Generally,

the ratio pd / p

s decreases with increasing cartridge

chamber shape coefficient χ and with decreasing

ratio ω / mq. Further the Figure shows that there

are, according to this model, certain combinations

of cartridge chamber shapes coefficients χ and

ratios ω / mq that gives p

d / p

s smaller than �; in

other words the breech pressure would be lower

than the projectile base one. This fact is, in case of

classical ballistic systems satisfying the condition

ω / mq < �, unexplainable.

2.1.3 moDel 3

The model 3 is also based on the model 1. This

time the model 1 is extended not only by the

effect of the shape of cartridge case chamber

χ but also by the effect of increasing volume of

the space behind the projectile expressed by the

projectile trajectory l and the pressure gradient is

written as

(9)

where: s - cross-sectional area of barrel, c0

- initial

volume of cartridge chamber.

The ratio pd / p

s was calculated again for

typical values and is shown in Figure 9. From the

figure is clearly seen that pd / p

s increases with the

trajectory of the projectile and also with ratio ω

/ mq. The increase of p

d / p

s is the steepest in the

beginning of projectile movement and later

becomes nearly constant.

Figure 8:Dependency of pd / p

s on cartridge chamber

shape coefficient χ(φ1 = 1.1, k = 0.3)


s on projectile’s

trajectory φ1 = 1.1, c0 / s = 0.4, χ = 1.75



high performance ballistic systems that still satisfy

the condition ω / mq < �.

2.1 moDels of PressUre GraDient

From the mentioned literatures the most

widespread models describing the pressure

gradient in the space behind a projectile were

chosen and were marked for needs of this paper as

model 1– 4. The fifth pressure distribution model

is used in the interior ballistic model described as

model STANAG �367.

Generally, it can be said, that basic element

of all analyzed models of pressure gradient is the

ratio , where: ω - mass of propellant charge, mq-

mass of the projectile.

2.1.1 moDel 1

This model is determined for ballistic systems with

a cylindrical cartridge chamber of the same area

of cross-section as area of cross-section of barrel,

Figure. 5.

In this model is the ratio of breech

pressure to the projectile base pressure expressed

as

(7)

trajectory. The dependency for common extent of

values ω / mq is shown in Figure. 7. From the Fig. 6

is clearly seen that according to the model 1 is the

pressure ratio pd / p

s directly proportional to the

ratio ω / mq.

ω2m

q

where: pd - breech pressure, p

s - projectile base

pressure, ω - mass of propellant charge, mq -

mass of projectile, φ� - losses coefficient (usually

between �.02 (howitzers and cannon) and �.�

(small arms �.05 – �.�).

In this model the ratio pd / p

s strongly

depends only on ratio ω / mq and remains constant

during the projectile movement inside the barrel,

i.e. the ratio is independent of the projectile


s on ratio ω / m

q and

φ1 = 1.1

Figure 7: Schematic of real cartridge chamber (lkom

≠ l

0)

2.1.2 moDel 2

A real cartridge chamber has usually bigger

diameter than the diameter of the barrel. This

model is based on the Model � and extended by

an effect of cartridge chamber shape. The effect of

the cartridge chamber shape is described by the

coefficient of cartridge chamber

shape , Figure 7.

The ratio of breech pressure pd to the projectile

base pressure ps is, in this model, described by

following empirical relation

(�)

where: χ ... coefficient of cartridge chamber shape,

k ... exponent (recommended value 0.3.

For calculation of exemplary courses

of pd / p

s were chosen typical extent of ratios ω /

mq from 0.2 to �.0, exponent k = 0.3 according to

recommendations from literature, and coefficient

φ1 = �.�. The obtained dependencies of p

d / p

s are

shown in Figure �.

The ratio pd / p

s is again independent of the projectile

trajectory and remains constant during the

projectile movement inside the barrel. Generally,

the ratio pd / p

s decreases with increasing cartridge

chamber shape coefficient χ and with decreasing

ratio ω / mq. Further the Figure shows that there

are, according to this model, certain combinations

of cartridge chamber shapes coefficients χ and

ratios ω / mq that gives p

d / p

s smaller than �; in

other words the breech pressure would be lower

than the projectile base one. This fact is, in case of

classical ballistic systems satisfying the condition

ω / mq < �, unexplainable.

2.1.3 moDel 3

The model 3 is also based on the model 1. This

time the model 1 is extended not only by the

effect of the shape of cartridge case chamber

χ but also by the effect of increasing volume of

the space behind the projectile expressed by the

projectile trajectory l and the pressure gradient is

written as

(9)

where: s - cross-sectional area of barrel, c0

- initial

volume of cartridge chamber.

The ratio pd / p

s was calculated again for

typical values and is shown in Figure 9. From the

figure is clearly seen that pd / p




d / p

s is the steepest in the

beginning of projectile movement and later

becomes nearly constant.

Figure 8:Dependency of pd / p

s on cartridge chamber

shape coefficient χ(φ1 = 1.1, k = 0.3)


s on projectile’s

trajectory φ1 = 1.1, c0 / s = 0.4, χ = 1.75



2.1.4 moDel 4

As a last of the most used models of the pressure

gradient in the space behind the projectile that

takes into account except ω and mq, also χ and

relative projectile trajectory Λ. The ratio pd / p

s is

given by following relation

, where: (�0)

For calculation was again chosen the typical

extent of ratios ω / mq from 0.2 to �.0. The

obtained dependencies are shown in Figure �0.

The figure shows that pd / p




d / p

s is again the steepest at

the beginning of projectile movement.

2.1.5 moDel stanaG 4367

In the Model STANAG �367 that is a part of the

interior ballistic model described is the ratio pd / p

s

given by the following relation

(��)

where: pr - resistance pressure against projectile

motion, pg -. pressure of gases ahead of projectile.

It can be seen that the ratio pd / p

s

depends not only on ω and mq but also on ratios

pr / ps and pd / p

s. All variables, with exception of

ω and mq, are time dependent, and so the ratio p

d

/ ps is not constant during projectile movement

inside the barrel. Typical course of ratio pd / p

s on

projectile’s trajectory is shown in Figure ��.

All previously analyzed models were used

for calculation of ratios pd / p

s for a ballistic systems

of calibre of 30 mm that was later also used for

experiments. Its ballistic characteristics were ω =

0.��5, mq = 0.3�9 kg, χ = �.9, ϕ

1 = �.03, c

0 = 2.3�9e-

� m3, s = 7.36�e-� m2. Obtained theoretical results

are summarized in Table �. Distances of individual

pressure gauges from back of barrel are shown in

Figure �3.

3. eXPeriments

For the validation of all previously mentioned

models of the pressure gradient in the space

behind the projectile it is necessary to know

the breech pressure pd and the projectile base

pressure ps. The experiment was focused on the

measurement of the pressure of propellant gases

at the breech and at the base of the projectile. The

measurement of the projectile base pressure was

realized by means of five piezoelectric pressure


s on projectile’s

trajectory φ1 = 1.1, c

0 / s = 0.4, χ = 1.75


s on projectile’s

trajectory

gauges placed along the barrel, Figure �3. The

projectile base pressure was read when the

projectile passed the individual pressure gauges.

For the experiment the ballistic testing weapon of

caliber of 30 mm weapon system was used. For the

test firings was used 30 mm practice ammunition,

ν0 = �000 m.s-�. The schematic of used ballistic

barrel with positions of piezoelectric pressure

gauges is shown in Figure �2.

corresponding breech pressures pd (Gauge No. �).

The evaluated values of both pressures together

with corresponding pressure ratios pd / p

s are

summarized in Table 2.

Figure 12: Schematic of ballistic barrel with positions of pressure gauges

Figure 13: Example of measured pressures

Example of measured pressures on all pressure


3.1 resUlts of eXPeriments their analysis

From obtained experimental data were determined

pressures at individual gauges (Gauges No. 2

- 6) at instant of projectile’s arrival ps and their

Table �: Results of calculations of pd / p

s from

individual models

Table 2: Results of experimental firings

Calculated and experimentally obtained ratios pd

/ ps are compared in Figure ��. At experimentally

obtained ratios pd / p

s are also shown their

corresponding standard deviations.

Figure 14: Comparison of experimental and calculated p

d / p

s

Figure 15: Trends on velocity and pressure profile due to wear



2.1.4 moDel 4

As a last of the most used models of the pressure

gradient in the space behind the projectile that

takes into account except ω and mq, also χ and

relative projectile trajectory Λ. The ratio pd / p

s is

given by following relation

, where: (�0)

For calculation was again chosen the typical

extent of ratios ω / mq from 0.2 to �.0. The

obtained dependencies are shown in Figure �0.

The figure shows that pd / p




d / p

s is again the steepest at

the beginning of projectile movement.

2.1.5 moDel stanaG 4367

In the Model STANAG �367 that is a part of the

interior ballistic model described is the ratio pd / p

s

given by the following relation

(��)

where: pr - resistance pressure against projectile

motion, pg -. pressure of gases ahead of projectile.

It can be seen that the ratio pd / p

s

depends not only on ω and mq but also on ratios

pr / ps and pd / p

s. All variables, with exception of

ω and mq, are time dependent, and so the ratio p

d

/ ps is not constant during projectile movement

inside the barrel. Typical course of ratio pd / p

s on

projectile’s trajectory is shown in Figure ��.

All previously analyzed models were used

for calculation of ratios pd / p

s for a ballistic systems

of calibre of 30 mm that was later also used for

experiments. Its ballistic characteristics were ω =

0.��5, mq = 0.3�9 kg, χ = �.9, ϕ

1 = �.03, c

0 = 2.3�9e-

� m3, s = 7.36�e-� m2. Obtained theoretical results

are summarized in Table �. Distances of individual

pressure gauges from back of barrel are shown in

Figure �3.

3. eXPeriments

For the validation of all previously mentioned

models of the pressure gradient in the space

behind the projectile it is necessary to know

the breech pressure pd and the projectile base

pressure ps. The experiment was focused on the

measurement of the pressure of propellant gases

at the breech and at the base of the projectile. The

measurement of the projectile base pressure was

realized by means of five piezoelectric pressure


s on projectile’s

trajectory φ1 = 1.1, c

0 / s = 0.4, χ = 1.75


s on projectile’s

trajectory

gauges placed along the barrel, Figure �3. The

projectile base pressure was read when the

projectile passed the individual pressure gauges.

For the experiment the ballistic testing weapon of

caliber of 30 mm weapon system was used. For the

test firings was used 30 mm practice ammunition,

ν0 = �000 m.s-�. The schematic of used ballistic

barrel with positions of piezoelectric pressure


corresponding breech pressures pd (Gauge No. �).

The evaluated values of both pressures together

with corresponding pressure ratios pd / p

s are

summarized in Table 2.

Figure 12: Schematic of ballistic barrel with positions of pressure gauges

Figure 13: Example of measured pressures

Example of measured pressures on all pressure


3.1 resUlts of eXPeriments their analysis

From obtained experimental data were determined

pressures at individual gauges (Gauges No. 2

- 6) at instant of projectile’s arrival ps and their

Table �: Results of calculations of pd / p

s from

individual models

Table 2: Results of experimental firings

Calculated and experimentally obtained ratios pd

/ ps are compared in Figure ��. At experimentally

obtained ratios pd / p

s are also shown their

corresponding standard deviations.

Figure 14: Comparison of experimental and calculated p

d / p

s

Figure 15: Trends on velocity and pressure profile due to wear



From comparison of results of calculations and

experimentally obtained pd / p

s follows that the

results of calculations are in good agreement with

experiment data, especially in the middle part

of the barrel. The only exception is the Model 2

whose results do not agree neither with results of

experiment nor with results of other models. This

disagreement is caused by inappropriate value of

the exponent k. From the comparison can be further

seen that at the beginning of projectile motion and

near the muzzle is the difference between results

of calculations and experiments more significant.

The Figure �5depicts the performances of the

�30mm higher caliber weapon system via pressure

vs velocity profile due to wear as an example.

4. conclUsion

We have described basic scientific concept of

interior ballistics and its attempted mathematical

models with its state-of-the-art CFD approach.

The existing models describing pressure gradient

phenomenon have been discussed and analyzed

with experimental data available in open literature

briefly. It is observed that the bigger difference

between measured and calculated ratios pd / ps near

the muzzle of the barrel can be explained by the leak

of propellant gases between barrel wall and driving

band that is at this stage of projectile movement

worn. Barrel wear usually also grows towards the

muzzle of barrel. The common disadvantage of all

the analyzed models is the fact that none of them

takes into account the leakage of propellant gases.

In other words, due to wear of the driving band is

changed the contact pressure between the driving

band and the barrel wall. The Model 2 requires more

suitable value of the exponent k to get into better

agreement with experimental results.

acKnoWleDGement

The authors are grateful to Maj Gen Praveen

Mathur, Director, Proof and Experimental

Establishment (PXE), Balasore, for his consent to

publish this paper.

references

[�] Understanding and predicting gun barrel erosion - Johnston A. J., Defence science and technology organisation, Edinburgh, Australia, 2005.

[2] Closed vessel ballistic assessment of gun propellant - DEF STAN �3–�9�/�, Ministry of Defence, Australia, �996.

[3] Propellants and Explosives - Kubota N., WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2007.

[�] NATO STANAG ��5, Definition and Determination of Ballistic Properties of Gun Propellants.

[5] Gun Propulsion Technology - Freedman, E., AIAA, �9��, American institute of aeronautics and astronautics, �9��. ISBN 0930�03207.

[6] Fluid-Structure Interaction in Interior Ballistic Environments- G.P Wren, S.E.Ray, T.E. Tezduyar and A. Hosangadi, �6th International Symposium on Ballistics, CA, September �996.

[7] Computation of In-bore Velocity-time and Travel-time profiles from Breech Pressure Measurements-D.K. Kankane and S.N. Ranade, Defence Science Journal Vol.53, No. �, October 2003.

[�] STANAG �367 Interior ballistic model with global parameters.

[9] Textbook of ballistics and gunnery-I & II. Editor LONGDON, L. W., London: Her Majesty’s stationery office, �9�7.

[�0] Burning surfaces evolution in solid propellants :a numerical model -J Szmelter and P Ortiz, Proc. IMechE Vol. 22� Part G: J. Aerospace Engineering, JAERO�02 © IMechE 2007.



PREDICTION OF BALLISTIC PARAMETERS OF GUN AMMUNITION

Dusmant Kumar Jena

Proof and Experimental Establishment, Chandipur, Balasore-756025

ABSTRACT

During development and acceptance of ammunition a number of trial firings are

undertaken to ascertain if the desired parameters i.e. range and accuracy are achieved.

Trial firing of ammunition involves variety of activities e.g. transportation of ammunition

from the manufacturer to the firing range, temporary storage at the range, provisioning

of requisite instrumentation at the range, positioning of trial team etc. and in addition,

co-ordination between a no. of external agencies. Thus, inordinate delays takes place

during development of ammunition stores. Besides, the cost factor also goes up with

repetition of the trials. Therefore, it would be highly beneficial to utilize the advanced

computing facility available today to simulate and predict the parameters without

actually firing the ammunition. And once the simulation confirms the achievement of

desired parameters a trial firing may be conducted to validate the simulation.

Key Words : Ammunition, Simulation, Propellant, Fluid Dynamics, Projectile

introDUction :

During development and acceptance of

ammunition a number of trial firings are

undertaken to ascertain if the desired parameters

i.e. range and accuracy are achieved. Trial firing

of ammunition involves variety of activities

e.g. transportation of ammunition from the

manufacturer to the firing range, temporary

storage at the range, provisioning of requisite

instrumentation at the range, positioning of trial

team etc. and in addition, co-ordination between

a no. of external agencies. Thus, inordinate delays

takes place during development of ammunition

stores. Besides, the cost factor also goes up

with repetition of the trials. Therefore, it would

be highly beneficial to utilize the advanced

computing facility available today to simulate and

Contributed Paper



predict the parameters without actually firing the

ammunition. And once the simulation confirms the

achievement of desired parameters a trial firing

may be conducted to validate the simulation.

internal Ballistics :

The firing sequence of a gun commences with the

ignition of primer of the cartridge either electrically

or by percussion. The hot gases generated by

ignition of the primer in turn initiates combustion

of propellant. At this stage the gun chamber is

virtually sealed by the projectile. So, the gases and

the energy liberated by the primer and propellant

get confined to a limited volume. Thus, resulting

in rapid increase in pressure and the temperature

within the chamber. The burning rate of propellant

is proportional to the chamber pressure. Therefore,

increase in chamber pressure leads to further

increase in the rate of gas generation. This process

would continue until the gun gets exploded.

This doesn’t, however, happen practically as the

projectile (which is crimped to the cartridge case)

starts moving along the barrel as soon as the

chamber pressure reaches a threshold level known

as shot-start pressure(as shown in graph).

With the projectile moving ahead

the volume to be filled in by the high pressure

propellant gasses also increases. At this point the

propellant is still burning and increase in volume

is much lesser compared to generation of high

pressure propellant gas. Therefore, the resultant

pressure keeps on increasing until the space

being created behind the accelerating projectile

exceeds the rate at which high pressure gas is

being produced. Thereafter, (after reaching the

maximum pressure) the pressure begins to fall.

The next stage is the all-burnt position

where the burning of propellant is completed.

Still, there remains a considerable amount of

pressure in the gun for the remaining motion

of the projectile along the bore. Therefore, the

projectile continues to accelerate even after the

all-burnt position. The moment the projectile

leaves the gun, the chamber pressure reduces to

about one sixth of the peak pressure.

Eg is the kinetic energy of the propellant gas

motion,

Eu is the kinetic energy of the unburnt

propellant motion,

Er is the kinetic energy due to recoil of the

gun,

Eb is the heat energy lost to the barrel,

Eh is the residual heat energy in the propellant

gasses,

Es is the strain energy used in expanding the

barrel,

Ef is the energy lost in engraving the driving

band and the overcoming friction in the

bore.

intermeDiate Ballistics :

As the projectile moves down the gun barrel, it

compresses the air ahead of it. The gun barrel acts

like a shock tube in which a near-planar shock

forms. When this shock exits the muzzle, it forms

a spherical shock wave . As the projectile moves

faster and faster in the barrel a second precursor

will be formed. This precursor moves faster than the

first one. The under-oxidised propellant gas reacts

with oxygen present in the precursor flow field

which gives rise to pre-flash. Several microseconds

after the precursor shock appears but before the

projectile exit a bottle shaped structure known as

bottle shock and an annular vortex is formed. All

these phenomena ultimately result in a bulge of

propellant gases through the precursor shock both

preceding and following the projectile.

eXterior Ballistics :

Once the projectile is out of the influence

of the propellant gases the flight of the

projectile is affected by the factors associated

with the atmosphere and the projectile itself.

The properties of atmosphere relevant to

the projectile flight trajectory are air density,

temperature, static pressure, viscosity and wind

speed direction. The projectile characteristics

which have some bearing on its flight trajectory

are its mass, caliber, shape and axial spin rate.

If the projectile happens to move in vacuum

the only force acting on a projectile in flight

is that due to gravitational acceleration. But in

air, there will be an additional force opposing

the forward motion of the projectile due to the

air resistance known as ‘drag’. The drag force

has three prime components which modify the

trajectory and these are : -

(a) Skin friction

(b) Pressure drag

(c) Yaw-dependent drag

methoDoloGy :

Computer models may be developed for internal,

intermediate and external ballistics for the

existing guns of caliber starting from 30mm to

�00mm. Thermophysics i.e. the quantification of

changes in a substance’s energy state caused by

changes in the physical state of the material and

Thermochemistry i.e. the quantification of changes

in a substance’s energy state caused by changes

in the chemical composition of the material’s

molecules and Thermodynamics i.e. the study

of energy transformations are to be taken into

account in detail while developing the model for

internal ballistics. Computational Fluid Dynamics

will be utilized to model the Intermediate ballistics.

There are two opposing forces acting

on a projectile within the gun barrel, namely

the propelling force due to the high pressure

propellant gas pushing the base of the projectile

and the frictional force between the projectile

and the bore (including the high resistance

due to engraving of Driving Band in the barrel

bore) opposing the motion of the projectile.

Additionally, the reaction between the projectile

and the rifling of a rifled gun translates a small

part of the propelling force into a torque which

causes the projectile to rotate. Any physical

system has to obey the principle of conservation

of energy. So, the total energy liberated in the

form of propellant gasses at high temperature,

which gets converted into other forms remains

the same. Therefore it may be written that : -

Et = E

p+E

g+E

u+E

r+E

b+E

n+E

s+E

f

Where Ep is the kinetic energy due to the

projectile motion,



predict the parameters without actually firing the

ammunition. And once the simulation confirms the

achievement of desired parameters a trial firing

may be conducted to validate the simulation.

internal Ballistics :

The firing sequence of a gun commences with the

ignition of primer of the cartridge either electrically

or by percussion. The hot gases generated by

ignition of the primer in turn initiates combustion

of propellant. At this stage the gun chamber is

virtually sealed by the projectile. So, the gases and

the energy liberated by the primer and propellant

get confined to a limited volume. Thus, resulting

in rapid increase in pressure and the temperature

within the chamber. The burning rate of propellant

is proportional to the chamber pressure. Therefore,

increase in chamber pressure leads to further

increase in the rate of gas generation. This process

would continue until the gun gets exploded.

This doesn’t, however, happen practically as the

projectile (which is crimped to the cartridge case)

starts moving along the barrel as soon as the

chamber pressure reaches a threshold level known

as shot-start pressure(as shown in graph).

With the projectile moving ahead

the volume to be filled in by the high pressure

propellant gasses also increases. At this point the

propellant is still burning and increase in volume

is much lesser compared to generation of high

pressure propellant gas. Therefore, the resultant

pressure keeps on increasing until the space

being created behind the accelerating projectile

exceeds the rate at which high pressure gas is

being produced. Thereafter, (after reaching the

maximum pressure) the pressure begins to fall.

The next stage is the all-burnt position

where the burning of propellant is completed.

Still, there remains a considerable amount of

pressure in the gun for the remaining motion

of the projectile along the bore. Therefore, the

projectile continues to accelerate even after the

all-burnt position. The moment the projectile

leaves the gun, the chamber pressure reduces to

about one sixth of the peak pressure.

Eg is the kinetic energy of the propellant gas

motion,

Eu is the kinetic energy of the unburnt

propellant motion,

Er is the kinetic energy due to recoil of the

gun,

Eb is the heat energy lost to the barrel,

Eh is the residual heat energy in the propellant

gasses,

Es is the strain energy used in expanding the

barrel,

Ef is the energy lost in engraving the driving

band and the overcoming friction in the

bore.

intermeDiate Ballistics :

As the projectile moves down the gun barrel, it

compresses the air ahead of it. The gun barrel acts

like a shock tube in which a near-planar shock

forms. When this shock exits the muzzle, it forms

a spherical shock wave . As the projectile moves

faster and faster in the barrel a second precursor

will be formed. This precursor moves faster than the

first one. The under-oxidised propellant gas reacts

with oxygen present in the precursor flow field

which gives rise to pre-flash. Several microseconds

after the precursor shock appears but before the

projectile exit a bottle shaped structure known as

bottle shock and an annular vortex is formed. All

these phenomena ultimately result in a bulge of

propellant gases through the precursor shock both

preceding and following the projectile.

eXterior Ballistics :

Once the projectile is out of the influence

of the propellant gases the flight of the

projectile is affected by the factors associated

with the atmosphere and the projectile itself.

The properties of atmosphere relevant to

the projectile flight trajectory are air density,

temperature, static pressure, viscosity and wind

speed direction. The projectile characteristics

which have some bearing on its flight trajectory

are its mass, caliber, shape and axial spin rate.

If the projectile happens to move in vacuum

the only force acting on a projectile in flight

is that due to gravitational acceleration. But in

air, there will be an additional force opposing

the forward motion of the projectile due to the

air resistance known as ‘drag’. The drag force

has three prime components which modify the

trajectory and these are : -

(a) Skin friction

(b) Pressure drag

(c) Yaw-dependent drag

methoDoloGy :

Computer models may be developed for internal,

intermediate and external ballistics for the

existing guns of caliber starting from 30mm to

�00mm. Thermophysics i.e. the quantification of

changes in a substance’s energy state caused by

changes in the physical state of the material and

Thermochemistry i.e. the quantification of changes

in a substance’s energy state caused by changes

in the chemical composition of the material’s

molecules and Thermodynamics i.e. the study

of energy transformations are to be taken into

account in detail while developing the model for

internal ballistics. Computational Fluid Dynamics

will be utilized to model the Intermediate ballistics.

There are two opposing forces acting

on a projectile within the gun barrel, namely

the propelling force due to the high pressure

propellant gas pushing the base of the projectile

and the frictional force between the projectile

and the bore (including the high resistance

due to engraving of Driving Band in the barrel

bore) opposing the motion of the projectile.

Additionally, the reaction between the projectile

and the rifling of a rifled gun translates a small

part of the propelling force into a torque which

causes the projectile to rotate. Any physical

system has to obey the principle of conservation

of energy. So, the total energy liberated in the

form of propellant gasses at high temperature,

which gets converted into other forms remains

the same. Therefore it may be written that : -

Et = E

p+E

g+E

u+E

r+E

b+E

n+E

s+E

f

Where Ep is the kinetic energy due to the

projectile motion,



The models developed for internal and

intermediate ballistics will provide the Muzzle

velocity of the projectile. For External Ballistics

the Six-Degrees-of-Freedom (6-DOF) trajectory

models may be exploited. Experimentation with

wind tunnels is required to be carried out to

determine aerodynamic co-efficient of projectile.

Muzzle velocity obtained from internal and

intermediate ballistic model and aerodynamic co-

efficient determined with the help of wind tunnel

experimentation will be fed to 6-DOF trajectory

model to predict the projectile trajectory.

Computer Programming language C, C++,

MATLAB and Ballistic software

package PRODAS are the available options for

computation.

These models will be validated by

comparing the outputs of the models with the

practical data generated during the actual firings

of the guns. Once validated these models will be

utilized for guns/projectiles being developed/for

future development.

conclUsion :

The sequence of operations during firing

i.e. starting from the primer initiation until the exit

of projectile from the muzzle (Internal ballistics),

motion of the projectile in the close vicinity of the

gun muzzle (Intermediate ballistics) and the flight

trajectory of projectile in air (external ballistics) can

be modeled using advanced computing facilities

with a view to predicting the projectile trajectory

and the fall of shot. In the earlier days this was

being done by mathematical analysis. However,

the mathematical functions being continuous

in nature are not appropriate to model Internal

ballistics, which is a discontinuous process.

On the contrary computer model will

have many advantages over analytical models.

It will have the capability to include realistic

data and functions, which can effectively model

discontinuous processes like ignition of primer

and propellant and engraving of Driving band.

Computer models are much more flexible in the

sense that various parameters of the projectile

propellant or the gun can be changed frequently

to arrive at the optimum combination. Further,

with the availability of advanced high speed

computing facilities it is possible to predict

the flight trajectory of gun projectile, which is

the ultimate measure of the gun performance.

Therefore, it is indeed worth experimenting the

gun systems design with the help of computer

simulations, which has the capability to predict

the gun performance without firing a shot.

references :

[�] G.M. Moss,D.W. Leeming and C Farrar : Military Ballistics

[2] Text book of Gunnery prepared by the Ordnance College, Woolwich, UK

[3] DE Carlucci and SS Jacobson : Theory and Design of Guns and Ammunition

[�] Robert L McCoy : Modern Exterior Ballistics [5] J Sahu, KR Heavey and R Buretta : CFD Modelling of

a Course Corrected Artillery Projectile at Transonic Speeds

[6] H Jung, U Hwang and J kim : Aerodynamic and Ballistic Analysis of Rifled Mortar Munition



MORPHOLOGICAL AND ELECTRICAL PROPERTIES OF POLY(M-TOLUIDINE)/MODIFIED MWCNT CONDUCTING POLYMER COMPOSITES.

Matru Prasad Dash�, G.C. Mohanty2 & P.L.Nayak�

�.P.L.Nayak Research Foundation, Neelachal Bhavan, Cuttack- 75300�, India

2.Dept. of Physics Ravenshaw University,Cuttack-753003, India

Corresponding Author : Prof. P.L.Nayak

Email : plnayak @rediffmail.com

Abstract

We describe here the synthesis of hydrochloric acid (HCl) doped poly(m-toluidine)

(PMT) with carboxylic groups containing multi-walled carbon nanotubes (c-MWCNTs)

via in situ polymerization. m-Toluidine monomers were adsorbed on the surface of

MWCNTs and polymerized to form PMT/c-MWCNT composites. The composites were

characterized by using FTIR, SEM, TEM and XRD analysis. Scanning electron microscopy

(SEM) and transmission electron microscopy (TEM) images showed that both the thinner

fibrous phase and the larger block phase could be observed. The individual fibrous

phases had diameters about 100 nm, and therefore must be the carbon nanotubes

(diameter 20–30 nm) coated by a PMT layer. The electrical conductivities of PMT/c-

MWCNT composites were improved relative to those of PMT without c-MWCNTs.

Keywords: MultiwalledCarbonnanotube(MWCNT), poly(m-toluidine); polymerization; conducting

polymer

1.introduction

Carbon nanotubes (CNTs) including

multi-walled and single-walled carbon nanotubes

(MWCNTs and SWCNTs, respectively) with

exceptional structural, mechanical and electronic

properties [�, 2] have received considerable interest

in fabricating advanced functional materials [3, �].

Currently, much attention is paid to the formation

of CNTs/conducting polymer composites which

are considered as a promising approach to exploit

synergetic effects arising from the components

and show potential for many electronic devices

such as PEDOT/CNTs in organic light emitting

diodes, PPV/CNTs in photovoltaic cells, PPy/ CNTs

in battery and PANI/CNTs in supercapacitors [5–7].

Among various conducting polymers, PANI is a

promising candidate for practical applications due

Contributed Paper



to its good processibility, environmental stability

and reversible control of electrical properties by

both charge-transfer doping and protonation [�].

However, the major disadvantage of PANI/CNT is

its insolubility in common organic solvents and its

infusibility. Preparation of alkyl group substituted

PANI/CNT is a method to obtain soluble PANI/

CNT composites. Soluble methyl-substituted

PANI called poly (m-toluidine) (PMT) have been

synthesized by electrochemical and chemical

method. Recently, PMT was also found to have

additional advantage with respect to PANI due

to its faster switching time between the oxidized

and the reduced states .Fig. � outlines the four

different oxidation states of PMT.

In the present communication, we wish to

describe the synthesis and characterization of PMT

with MWCNT fabricated by in situ polymerization

.The nanocomposites were characterized by

a number of techniques including scanning

electron microscopy (SEM), transmission electron

microscopy (TEM), and electrical conductivity.

2.Work-up procedure.

2.1 Materials.

m-Toulidine was purchased from Aldrich,

Multi-walled CNT (<90% purification) used in this

study was purchased from Cheap Tubes (USA, �0–

20 nm diameter). Other reagents like ammonium

persulfate (APS), hydrochloric, sulfuric, and nitric

acid (Sigma Chemicals) were of analytical grade.

2.2 Oxidation of MWCNT:

MWCNTs (0.30 g) were suspended in 20

ml of a 3:� (v) mixture of concentrated H2SO

� (9�

wt%)/HNO3 (60 wt%). The above mixture was

sonicated in a water bath for 2 h, and stirred for

�5 h at 350C. Then the mixture was diluted with

�00 ml of distilled water, vacuum-filtered and

washed with distilled water until pH of the filtrate

was 7.0. The filtered solid was dried under vacuum

for 20 h at 600C, obtaining carboxyl-functionalized

MWCNTs (MWCNT-COOH) (0.2� g).

2.3 Synthesis of PMT/c-MWCNT polymer

composites.

PMT/c-MWCNT composites were

synthesized by in situ chemical oxidative

polymerization. In a typical composite

synthesis experiment, various weight ratio

of c-MWCNTs were dissolved in �0mL �M

hydrochloric acid solutions and ultrasonicated

over 2 h, then transferred into a 250mL beaker.

0.�2� g m-toluidine monomer was added to

the above c-MWCNTs suspension. Then a 20ml

�M hydrochloric acid solution containing 0.9�2

g ammonium persulfate (APS) was added into

the suspension with constant mechanical

stirring at room temperature. The reaction

mixture was stirred for a further �2 h, and then

Fig. 1. Four different redox forms of PMT: (a) leucoemeraldine base (fully reduced form), (b) emeraldine base (halfoxidized form), (c) conducting emeraldine salt (half-oxidized and protonated form), and (d) pernigraniline base (fully oxidized form).



filtered. The remaining filter cake was rinsed

several times with distilled water and ethanol.

The power thus obtained was dried under

vacuum at 600C for 2� h. The % of c-MWCNT

were used 0, 2, 5%.

3. measurements.

3.1Morphology

Morphology of the PMT/c-MWCNT

composite was investigated using a Philip XL 30

SEM at an accelerating voltage of 25 kV. The sample

was fractured at liquid nitrogen temperature and

then was coated with a thin layer of gold before

observation.

3.2 TEM

TEM experiments were performed on

a Hitachi H-��00 electron microscope with an

acceleration voltage of 200 kV.

3.3 Conductivity.

The standard Van Der Pauw DC four-

probe method was used to measure the

electron transport behaviors of PMT and PMT/

c-MWCNT composites. The samples of PMT and

PMT/c-MWCNTs were pressed into pellet. The

pellet was cut into a square. The square was

placed on the four probe apparatus, providing

a voltage for the corresponding electrical

current could be obtained. The electrical

conductivity of samples was calculated by the

following formula: σ (S/cm) = (2.�� ×�0/S) ×

(I/E), where σ is the conductivity, S the sample

side area, I the current passed through outer

probes, and E the voltage drop across inner

probes.

4. results and discussion.

Fig 2. SEM images of; a.. c-MWCNT; b.PMT/c-MWCNT (2%); c.PMT/c-MWCNT (5%)

4.1. SEM

The SEM pictures of the pristine c-

MWCNTs, and nanocomposite with 2, and 5, % of c-

MWCNTs are presented in Fig.2. Figure 2a shows the

disentanglement of the c-MWCNTs, and the slight

reduction in the length of the nanotube is observed

after oxidation with 3:� concentrated H2SO� and

HNO3 mixture. In the case of nanocomposites (Fig.

2b,2c), a tubular layer of coated copolymer film is

clearly present on the surface of c-MWCNTs, and

the diameter of the nanocomposite is increased

substantially as compared to that of the c-MWCNTs,

depending on the copolymer content. From this



observation, it can be attributed that the coating

of copolymer takes place only at the outer surface

of the c-MWCNTs. The formation of the copolymer-

coated tubular nanocomposite is believed to

arise from the strong interaction between the

co-monomer and c-MWCNTs. This interaction is

thought to be made up of two components: one is

the π–π electron interaction between the MWCNTs

and the comonomer [9] and the other is the

hydrogen bond interaction between the carboxyl

group of the c-MWCNTs and amino group of the

co-monomers. Such a strong interaction ensures

that the co-monomer molecules are adsorbed on

the surface of the c-MWCNTs. The polymerization

of co-monomer inside the c-MWCNTs is hindered

by the restricted access of the reactants to the

interior of the c-MWCNTs because of the presence

of the carboxyl group at the meta position of the

co-monomer. This is in agreement with the findings

reported in the literature [�0].

4.2.TEM:

The TEM spectra of the c-MWCNT and

PMT with 5% c-MWCNT are presented in Figure3.

The uniform deposition of PMT on the c-MWCNT

is similarly demonstrated by transmission electron

microscopy (TEM), which shows the bilayered

structure of coated C-MWCNT. As the internal

cavity is well discernible, we conclude that the

coating with PMT takes place only at the outer

surface of thec-MWCNT. The polymerization of

PMT inside the c-MWCNT is hindered by the

restricted access of reactants to the interior

of the c-MWCNT. The comonomer molecules

are uniformly polymerized on the surface of c-

MWCNTs and form a tubular nanocomposite. The

diameter of the nanocomposite becomes larger

than that of the c-MWCNTs after polymerization.

4.3 Conductivity:

Fig3. TEM image of a.MWCNT.b.PMT/c-MWCNT (5%)

Fig. 4. Conductivity versus the weight percent of c-MWCNT/PMTcomposites

The electrical conductivities PMT and

PMT/c- MWCNT composites are measured using

the standard Van Der Pauw DC four-probe method

and shown in Figure �. The conductivity of MWCNT

is about 0.2 S/cm. The conductivities of PMT

synthesized in the presence of hydrochloric acid

shows a room temperature conductivity of 2.�×�0−�



S/cm . The lower room temperature conductivity

of PMT than PANI probably has something to do

with its substituted group and low protonic acid

doping degree. Meanwhile, the addition of 2 wt.%

c-MWCNT into PMT, the conductivity at room

temperature increases from 2.� to 7×�0−� S/cm. With

the continuous increase in the content of c-MWCNT,

the conductivity at room temperature gradually

increases from 7×�0−� S/cm for 2 wt.% MWCNT-

containing PMT/c-MWCNT composites to 9×�0−�S/

cm for 5 wt.% MWCNT containing PMT/c-MWCNT

composites. The conductivities of PMT/c-MWCNT

composites with 5 wt.% c-MWCNTs content at room

temperature are much more higher than those of

PMT without c-MWCNTs. The reason is probably that

c-MWCNTs serve as a “conducting bridge” between

the PMT conducting domains, which increases the

effective percolation.

5. Conclusion

PMT/c-MWCNTs nanocomposites were

successfully synthesized via in situ polymerization

method. SEM and TEM measurement ascertained

that the c-MWCNTs were homogeneously

dispersed in the copolymer matrix. Room

temperature conductivity of nanocomposite

increased several times as increasing of percentage

of c-MWCNT .In addition, the versatility of this

method could be extended to prepare other

polymer/ CNT nanocomposites by choosing

appropriate experimental conditions

Acknowledgments:

The authors are thankful to Dr.S.Sasmal, Principal

Scientist, CRRI, Cuttack for encouragements and

Dr. Munesh Chandra Adhikary for suggestions.

6. references:

[�] Iijima S., Ichihashi T: Single-shell carbon nanotubes of �-nm diameter.Nature, 363, 603-605 (�993).

[2] Iijima S: Helical microtubules of graphitic carbonNature ,35�, 56-5� (�99�).

[3] Ajayan P.M., Stephan O., Colliex C., Trauth D:Aligned Carbon Nanotube Arrays Formed by Cutting a Polymer Resin—Nanotube Composite Science, 265, �2�2-�2�� (�99�).

[�] Wong E.W., Sheehan P.E., Lieber C.M.:Nanobeam Mechanics: Elasticity, Strength and Toughness of Nanorods and Nanotubes ,Science ,277, �97�-�975 (�997).

[5] Woo H.S., Czerw R., Webster S., Carroll D.L: Organic light emitting diodes fabricated with single wall carbon nanotubes dispersed in a hole conducting buffer: the role of carbon nanotubes in a hole conducting polymer,Synth. Met. ��6, 369-372 (200�).

[6] Ago H., Petritsch K., Shaffer M.S.P., Windle A.H., Friend R.H., Composites of Carbon Nanotubes and Conjugated Polymers for Photovoltaic Devices, Adv. Mater. ��, �2��-�2�5, (�999).

[7] Sivakkumar S.R., Kima W.J.,. Choi J.A, MacFarlane D.R., Forsyth M., Kima D.W:Electrochemical performance of polyaniline nanofibres and polyaniline/multi-walled carbon nanotube composite as an electrode material for aqueous redox supercapacitors, J. Power Sources ,�7�, �062 (2007).

[�] Premamoy G., Samir K.S., Amit C:Characterization of poly(vinyl pyrrolidone) modified polyaniline prepared in stable aqueous medium,Eur. Polym. J, 35,699-7�0(�999).

[9] A Star, JF Stoddart, D Steuerman, M Diehl, A Bouaki, EW Wong, X Yang, SW Chung, H Choi, JR Heath Angew Chem Int Ed ,�0,�72�(200�).

[�0] Deng M., Yang B., Hu Y:Polyaniline deposition to enhance the specific capacitance of carbon nanotubes for supercapacitors, J Mater Sci ,�0,502�-5023(2005)



ABSTRACT

In the present study, we report modification of pulsed laser deposited c-axis oriented thin films

of YBa2Cu

3O

7-y (YBCO) by secondary electrons emitted radially in a cylindrical region around the

path of swift heavy ions. Our in situ temperature dependent resistivity measurement and in situ

low temperature x-ray diffraction (XRD) study on YBCO irradiated at liquid N2 temperature with

200 MeV Ag ions showed that these secondary electrons selectively create point defects at CuO

basal chains of YBCO. These low energy secondary electrons create defects by inelastic interaction

process. These defects frozen by low temperature irradiation lead to decrease of Tc and integrated

XRD intensity of (00l) peak at low fluences, where ion induced amorphous latent tracks are far

apart from each other. Beyond a critical fluence (1012 ions cm-2), the radially strained region around

the amorphous latent tracks tend to overlap and a two step superconducting transition evolves

instead of a single transition.

A REPORT ON LOW TEMPERATURE IRRADIATION STUDY IN YBa2Cu

3O

7-y

SUPERCONDUCTOR

R. Biswal and N.C. Mishra

Department of Physics, Utkal University, Bhubaneswar 75�00�

Email:[email protected], [email protected]

Keywords: Swift heavy ion irradiation, cuprate superconductor, secondary electrons,

introDUction

The discovery of superconductivity has been

recognized as one of the greatest scientific

achievements of twentieth century. The materials,

which obeyed this phenomenon was called as the

superconductor. It is basically a state of matter

below certain temperature where the dc resistivity

suddenly drops to zero. This temperature is known

as superconducting transition temperature (Tc)

and is defined for every specific material. In �9��,

Heike Kamerlingh-Onnes and his assistant Gilles

Holst were discovered the superconductivity

phenomenon in mercury at very low temperature

in their Leiden laboratory in �9�� [�]. The

mechanism of superconductivity was proposed

by J. Bardeen, L. Cooper and R. Schrieffer long �6

years after its discovery, in �957 for which they

were jointly awarded the Noble prize. Another

breakthrough came in �9�6 with Bednorz and

Muller discovering superconductivity in ceramic

matter, which is normally a good insulator. This

opened up a new branch of superconductivity,

now known as the high Tc superconductivity

(HTSC). One year after, the discovery of a new rare

earth based copper oxide superconductor,

YBa2Cu

3O

7-y [2], which was the first material having

a transition temperature Tc higher than the

boiling point of liquid nitrogen, took the world by

storm. The mechanism has remained an enigma.

People worked in its different aspects at an

unprecedented pace, because of the technological

prospects, this enigmatic phenomenon of lossless

electric energy transmission coupled with

complete diamagnetic properties, tunneling

etc it promised. Understanding the still elusive

mechanism of superconductivity in these high

Tc superconducting systems and exploring their

application possibilities have involved modifying

the properties of these systems by varieties of

methods. At the microscopic scale, these methods

include doping at different lattice sites of the

complex planner structure of HTSC systems and

irradiation by ion beams. Here, a short summary and

discourse on the modification of YBa2Cu

3O

7-y (YBCO)

thin films by swift heavy ion (SHI) irradiation

induced secondary electrons at low temperature

is presented.

At high energies, heavy ions dissipate

energy mostly to the electrons along the trajectory

in the target medium. The excited electrons

confined to the ion path transfer their energy to

lattice in a very short period and the consequent

modifications are the amorphous latent track

creation along the ion trajectory when the

electronic energy loss, Se exceeds a threshold value,

i.e., Se>S

eth [3], creation of defects [�], annealing of

the pre-existing defects [5], changes of phases

around the ion path [6], and also a macroscopic flow

of matter [7] in amorphous materials. However, a

fraction of highly excited electrons may leave the

ion path and enter into the surrounding pristine

materials which are called as secondary electrons

(SE). A few secondary electrons may also come

out from the target material if these have enough

energy [�]. The trapped SEs are, being of very

low energy, not known to create lattice disorder

elastically however these electrons can cause

photo-luminescence emission in alkali halides.

The question we address here; can the secondary

electrons trapped in the materials medium

create defect by any other means, if not by elastic

scattering. In YBCO thin films, we show that these

SE can indeed create defects by inelastic electron

capture process as in dissociative recombination

observed in organic and polymeric materials.

It is widely known that the

superconducting and normal state properties

of YBCO, an extensively studied high Tc

superconductor, are strongly influenced by

disorder in the CuO chains [9,�0]. Chains are not

continuous but broken into segments of finite

length due to presence of the vacant oxygen sites.

Oxygen disorders in the form of vacancy in the

chains reduce the average chain length with a

direct influence on the hole (carrier) concentration

and hence the Tc. Shorter chains yield reduced

carrier densities, while chain merging results

in increased carrier concentrations [9]. Oxygen

disorder in CuO chain of YBCO has been achieved

by quenching of samples from high temperatures

to liquid nitrogen temperature and the Tc increase

observed in room temperature annealed bulk

samples has been interpreted in terms of an

increase in the carrier density resulting from chain

ordering [�0]. At high temperatures, not only the

Contributed Paper



ABSTRACT

In the present study, we report modification of pulsed laser deposited c-axis oriented thin films

of YBa2Cu

3O

7-y (YBCO) by secondary electrons emitted radially in a cylindrical region around the

path of swift heavy ions. Our in situ temperature dependent resistivity measurement and in situ

low temperature x-ray diffraction (XRD) study on YBCO irradiated at liquid N2 temperature with

200 MeV Ag ions showed that these secondary electrons selectively create point defects at CuO

basal chains of YBCO. These low energy secondary electrons create defects by inelastic interaction

process. These defects frozen by low temperature irradiation lead to decrease of Tc and integrated

XRD intensity of (00l) peak at low fluences, where ion induced amorphous latent tracks are far

apart from each other. Beyond a critical fluence (1012 ions cm-2), the radially strained region around

the amorphous latent tracks tend to overlap and a two step superconducting transition evolves

instead of a single transition.

A REPORT ON LOW TEMPERATURE IRRADIATION STUDY IN YBa2Cu

3O

7-y

SUPERCONDUCTOR

R. Biswal and N.C. Mishra

Department of Physics, Utkal University, Bhubaneswar 75�00�

Email:[email protected], [email protected]

Keywords: Swift heavy ion irradiation, cuprate superconductor, secondary electrons,

introDUction

The discovery of superconductivity has been

recognized as one of the greatest scientific

achievements of twentieth century. The materials,

which obeyed this phenomenon was called as the

superconductor. It is basically a state of matter

below certain temperature where the dc resistivity

suddenly drops to zero. This temperature is known

as superconducting transition temperature (Tc)

and is defined for every specific material. In �9��,

Heike Kamerlingh-Onnes and his assistant Gilles

Holst were discovered the superconductivity

phenomenon in mercury at very low temperature

in their Leiden laboratory in �9�� [�]. The

mechanism of superconductivity was proposed

by J. Bardeen, L. Cooper and R. Schrieffer long �6

years after its discovery, in �957 for which they

were jointly awarded the Noble prize. Another

breakthrough came in �9�6 with Bednorz and

Muller discovering superconductivity in ceramic

matter, which is normally a good insulator. This

opened up a new branch of superconductivity,

now known as the high Tc superconductivity

(HTSC). One year after, the discovery of a new rare

earth based copper oxide superconductor,

YBa2Cu

3O

7-y [2], which was the first material having

a transition temperature Tc higher than the

boiling point of liquid nitrogen, took the world by

storm. The mechanism has remained an enigma.

People worked in its different aspects at an

unprecedented pace, because of the technological

prospects, this enigmatic phenomenon of lossless

electric energy transmission coupled with

complete diamagnetic properties, tunneling

etc it promised. Understanding the still elusive

mechanism of superconductivity in these high

Tc superconducting systems and exploring their

application possibilities have involved modifying

the properties of these systems by varieties of

methods. At the microscopic scale, these methods

include doping at different lattice sites of the

complex planner structure of HTSC systems and

irradiation by ion beams. Here, a short summary and

discourse on the modification of YBa2Cu

3O

7-y (YBCO)

thin films by swift heavy ion (SHI) irradiation

induced secondary electrons at low temperature

is presented.

At high energies, heavy ions dissipate

energy mostly to the electrons along the trajectory

in the target medium. The excited electrons

confined to the ion path transfer their energy to

lattice in a very short period and the consequent

modifications are the amorphous latent track

creation along the ion trajectory when the

electronic energy loss, Se exceeds a threshold value,

i.e., Se>S

eth [3], creation of defects [�], annealing of

the pre-existing defects [5], changes of phases

around the ion path [6], and also a macroscopic flow

of matter [7] in amorphous materials. However, a

fraction of highly excited electrons may leave the

ion path and enter into the surrounding pristine

materials which are called as secondary electrons

(SE). A few secondary electrons may also come

out from the target material if these have enough

energy [�]. The trapped SEs are, being of very

low energy, not known to create lattice disorder

elastically however these electrons can cause

photo-luminescence emission in alkali halides.

The question we address here; can the secondary

electrons trapped in the materials medium

create defect by any other means, if not by elastic

scattering. In YBCO thin films, we show that these

SE can indeed create defects by inelastic electron

capture process as in dissociative recombination

observed in organic and polymeric materials.

It is widely known that the

superconducting and normal state properties

of YBCO, an extensively studied high Tc

superconductor, are strongly influenced by

disorder in the CuO chains [9,�0]. Chains are not

continuous but broken into segments of finite

length due to presence of the vacant oxygen sites.

Oxygen disorders in the form of vacancy in the

chains reduce the average chain length with a

direct influence on the hole (carrier) concentration

and hence the Tc. Shorter chains yield reduced

carrier densities, while chain merging results

in increased carrier concentrations [9]. Oxygen

disorder in CuO chain of YBCO has been achieved

by quenching of samples from high temperatures

to liquid nitrogen temperature and the Tc increase

observed in room temperature annealed bulk

samples has been interpreted in terms of an

increase in the carrier density resulting from chain

ordering [�0]. At high temperatures, not only the

Contributed Paper



oxygen in the CuO chains are disordered, but also

the oxygen content is reduced below the optimal

value for highest Tc. Thus subsequent annealing

of quenched samples at RT had led to evolution

of ortho-II structure and increase of Tc to ~ 60 K

corresponding to this structure.

We however show that low energy

secondary electrons can create oxygen defects

inelastically in YBCO matrix with optimal oxygen

content. These secondary electrons primarily

dislodge oxygen atoms selectively from the CuO

chains, since this is the lightest and more loosely

bound species of the structure.

material anD methoDs

In situ temperature dependent resistivity, ρ(T) below

�30 K and in situ low temperature x-ray diffraction

(XRD) measurements have been undertaken to

study the evolution of the defect structure by SHI

irradiation induced secondary electrons in YBCO

matrix where the defects sensitively influence the

superconducting characteristics and the crystal

structure. Sintered YBCO target was prepared by

conventional solid-state reaction route. Thin films

of YBCO were deposited from this sintered bulk

target by pulsed laser deposition technique on

single crystal LaAlO3 substrate [��]. The films of

�50 nm thick were irradiated with 200 MeV �07Ag

ions using the �5 UD tandem pelletron accelerator

at the IUAC, New Delhi.

The electronic energy loss, Se, nuclear

energy loss, Sn, and range of the 200 MeV Ag ions

in YBCO calculated from SRIM 2006 are 25.�� keV

nm-�, 70.95 eV nm-� and �2.66 µm respectively.

Since the thickness of the sample is much less than

the range of the ion beams, the ions are implanted

much deeper in the substrate. Also the Se is almost

same throughout the film thickness implying the

uniform energy deposition in the sample and

mostly due to Se. Since the S

e of 200 MeV Ag ions

in YBCO exceeds its threshold value, Seth

(~ 20 keV

nm-�) [�2], these ions create amorphized latent

tracks along their trajectory in the films.

The irradiation fluence, Φ was varied

from �×�09 ions cm-2 to 2 ×�0�3 ions cm-2. In situ

temperature dependent resistivity, ρ(T) was

measured after irradiating the sample at �2 K with

ion beams at different fluences. The ρ(T) data

were taken right after irradiation in heating cycle

up to a maximum temperature of �30 K. In these

measurements, the sample temperature was thus

kept well below room temperature (RT) to avoid

annealing of irradiation-induced defects. The details

of the experiment is discussed in reference [��].

A Brucker X-ray diffractometer (Model

D�) installed in the beam line was used to collect

XRD data in situ using Cu Kα radiation after each

fluence of irradiation at �9 K [�3]. Here also the

sample temperature was kept well below RT to

freeze the irradiation induced defects.

resUlts anD DiscUssion

In situ temperature dependent resistivity study The

variation of resistivity as a function of temperature,

ρ(T) of a YBCO thin film at different ion fluences

are shown in figures � and 2. Depending upon the

nature of resistivity variation with temperature,

three different fluence regimes are identified. The

low fluence regime corresponds to the fluence

φ ≤ �.7� × �0�� ions cm-2, where a single step

superconducting transition is observed and the

Tc and T

c0, extracted from the ρ(T) data, follow a

decreasing trend with irradiation fluence (Inset of

figure �).

Increasing fluence beyond �.7�×�0�� ions.cm-2,

though the two-step superconducting transition

could be seen up to a fluence of 6.�7×�0�2 ions

cm-2, the zero resistive state could not be achieved

above at the lowest irradiation temperature (�2 K)

(Figure 2). Increasing fluence in the mid-fluence

regime (6.7�×�0�� ions cm-2 ≤ Φ ≤ 6.�7×�0�2 ions

cm-2) causes only a slight decrease of Tc within 0.�

K (Inset (b) of figure 2). At the highest fluence of

�.�×�0�3 ions cm-2, superconductivity is completely

destroyed and ρ(T) showed a semiconducting

behavior and is termed as high flurnce regime

(Inset (a) of figure 2).

Irradiation at very low fluences and

at low temperatures has enabled us to look

into subtle features like the irradiation induced

metastable defect states, which anneal out at

higher temperature. We probe into the effect of

these metastable defects on the superconducting

transition of YBCO in the presence of a very few

number of stable amorphized latent tracks. While

literature reports the rate of Tc suppression is small

at low fluences and large at high fluences in YBCO

thin films irradiated at room temperature [��,�5].

On the contrary we find at very low fluences, the

rate of Tc suppression is two orders of magnitude

higher than that at high fluences. Defect recovery

due to annealing was studied in a few samples

by monitoring their ρ(T) behaviour immediately

after ion irradiation at low temperature and

after annealing the sample at 297 K for � hour.

The tendency of the superconducting transition

temperature and normal state resistivity to recover

to their pre-irradiation values indicates irradiation

induced defects are basically point defects which

anneal out at 297 K.

Figure �. Evolution of superconducting transition with irradiation at low fluences as probed through

resistivity vs. temperature measurement for thin film of YBa2Cu

3O

7-δ irradiated at �2 K by 200 MeV Ag

ions. The inset shows the Tc and T

c0 variation in this fluence range.



oxygen in the CuO chains are disordered, but also

the oxygen content is reduced below the optimal

value for highest Tc. Thus subsequent annealing

of quenched samples at RT had led to evolution

of ortho-II structure and increase of Tc to ~ 60 K

corresponding to this structure.

We however show that low energy

secondary electrons can create oxygen defects

inelastically in YBCO matrix with optimal oxygen

content. These secondary electrons primarily

dislodge oxygen atoms selectively from the CuO

chains, since this is the lightest and more loosely

bound species of the structure.

material anD methoDs

In situ temperature dependent resistivity, ρ(T) below

�30 K and in situ low temperature x-ray diffraction

(XRD) measurements have been undertaken to

study the evolution of the defect structure by SHI

irradiation induced secondary electrons in YBCO

matrix where the defects sensitively influence the

superconducting characteristics and the crystal

structure. Sintered YBCO target was prepared by

conventional solid-state reaction route. Thin films

of YBCO were deposited from this sintered bulk

target by pulsed laser deposition technique on

single crystal LaAlO3 substrate [��]. The films of

�50 nm thick were irradiated with 200 MeV �07Ag

ions using the �5 UD tandem pelletron accelerator

at the IUAC, New Delhi.

The electronic energy loss, Se, nuclear

energy loss, Sn, and range of the 200 MeV Ag ions

in YBCO calculated from SRIM 2006 are 25.�� keV

nm-�, 70.95 eV nm-� and �2.66 µm respectively.

Since the thickness of the sample is much less than

the range of the ion beams, the ions are implanted

much deeper in the substrate. Also the Se is almost

same throughout the film thickness implying the

uniform energy deposition in the sample and

mostly due to Se. Since the S

e of 200 MeV Ag ions

in YBCO exceeds its threshold value, Seth

(~ 20 keV

nm-�) [�2], these ions create amorphized latent

tracks along their trajectory in the films.

The irradiation fluence, Φ was varied

from �×�09 ions cm-2 to 2 ×�0�3 ions cm-2. In situ

temperature dependent resistivity, ρ(T) was

measured after irradiating the sample at �2 K with

ion beams at different fluences. The ρ(T) data

were taken right after irradiation in heating cycle

up to a maximum temperature of �30 K. In these

measurements, the sample temperature was thus

kept well below room temperature (RT) to avoid

annealing of irradiation-induced defects. The details

of the experiment is discussed in reference [��].

A Brucker X-ray diffractometer (Model

D�) installed in the beam line was used to collect

XRD data in situ using Cu Kα radiation after each

fluence of irradiation at �9 K [�3]. Here also the

sample temperature was kept well below RT to

freeze the irradiation induced defects.

resUlts anD DiscUssion

In situ temperature dependent resistivity study The

variation of resistivity as a function of temperature,

ρ(T) of a YBCO thin film at different ion fluences

are shown in figures � and 2. Depending upon the

nature of resistivity variation with temperature,

three different fluence regimes are identified. The

low fluence regime corresponds to the fluence

φ ≤ �.7� × �0�� ions cm-2, where a single step

superconducting transition is observed and the

Tc and T

c0, extracted from the ρ(T) data, follow a

decreasing trend with irradiation fluence (Inset of

figure �).

Increasing fluence beyond �.7�×�0�� ions.cm-2,

though the two-step superconducting transition

could be seen up to a fluence of 6.�7×�0�2 ions

cm-2, the zero resistive state could not be achieved

above at the lowest irradiation temperature (�2 K)

(Figure 2). Increasing fluence in the mid-fluence

regime (6.7�×�0�� ions cm-2 ≤ Φ ≤ 6.�7×�0�2 ions

cm-2) causes only a slight decrease of Tc within 0.�

K (Inset (b) of figure 2). At the highest fluence of

�.�×�0�3 ions cm-2, superconductivity is completely

destroyed and ρ(T) showed a semiconducting

behavior and is termed as high flurnce regime

(Inset (a) of figure 2).

Irradiation at very low fluences and

at low temperatures has enabled us to look

into subtle features like the irradiation induced

metastable defect states, which anneal out at

higher temperature. We probe into the effect of

these metastable defects on the superconducting

transition of YBCO in the presence of a very few

number of stable amorphized latent tracks. While

literature reports the rate of Tc suppression is small

at low fluences and large at high fluences in YBCO

thin films irradiated at room temperature [��,�5].

On the contrary we find at very low fluences, the

rate of Tc suppression is two orders of magnitude

higher than that at high fluences. Defect recovery

due to annealing was studied in a few samples

by monitoring their ρ(T) behaviour immediately

after ion irradiation at low temperature and

after annealing the sample at 297 K for � hour.

The tendency of the superconducting transition

temperature and normal state resistivity to recover

to their pre-irradiation values indicates irradiation

induced defects are basically point defects which

anneal out at 297 K.

Figure �. Evolution of superconducting transition with irradiation at low fluences as probed through

resistivity vs. temperature measurement for thin film of YBa2Cu

3O

7-δ irradiated at �2 K by 200 MeV Ag

ions. The inset shows the Tc and T

c0 variation in this fluence range.



To explain the unexpected fast rate of Tc decrease

at very low fluences of irradiation, we consider

the effect of the SE in creation of point defects

around the amorphous track in YBCO matrix. The

estimated energy of these electrons however is

too low to create defects elastically. We invoke the

inelastic interaction of the low energy electrons

and show that YBCO offers an ideal platform where

SE can create defects by a process analogous to

dissociative recombination seen only in hydrogen

bonded molecules and organic medium [��]. The

point defects are the oxygen disorder in the CuO

chains of YBCO.

in situ low temperature X-ray diffraction study

The 2θ scan patterns of in situ low temperature

x-ray diffraction (XRD) spectra of YBCO film on

irradiation with 200 MeV Ag is shown in figure

3. The detailed values of peak position (2θ), peak

integrated intensity and the full width at half

maximum (FWHM) of (005) peak for all irradiation

fluences were given in TABLE I. The results are

summarized as follows: (i) The appearance of

only sharp (00l) peaks (l = 2 to 7) indicating

epitaxial nature of the film with grain orientation

along c-axis. (ii) No new peaks corresponding to

crystallographic planes other than (00l) up to the

highest fluence of irradiation (2×�0�3 ions cm-2)

appear. (iii) Spectra exhibit a sharp reduction in

(00l) peak intensity at low irradiation fluence (iv)

The (00l) peak shift towards lower angle with

increase of irradiation fluence, which is a sign of

expansion of the lattice parameter along the c-

axis (v) The full width at half maximum (FWHM)

of XRD peaks shows an incubation effect up to

�×�0�2 ions cm-2 and beyond which it increases.

Figure 2. The ρ(T) vs fluence in the mid fluence regime. To fit to the scale, the ρ(T) for the fluence 6.�7 ×

�0�2 ions cm-2 is divided by 3. Inset (a) shows the temperature dependence of resistance of YBCO films

irradiated at a fluence of � × �0�3 ions cm-2. Inset (b) shows the Tc vs fluence in the mid-fluence regime.

Figure 3 Evolution of low temperature (�9 K) in situ X-ray diffraction pattern of a YBa2Cu

3O

7-y thin film

with 200 MeV Ag ion irradiation fluence. In addition to (00l) peaks (l = 2 to 7) due to YBCO, there are

peaks due to the copper sample holder and the LaAlO3 substrate.

Fluence Peak Integrated intensity FWHM

(ion cm-2) centroid in degree

0 3�.6�3 266�.9 ± �6.� 0.2730� ± 0.002�2

�×�0�0 3�.635 2�77.37 ± �3.75 0.2752� ± 0.00�96

3×�0�0 3�.63� 2�32.0 ± �3.�2 0.27505 ± 0.00�95

�×�0�� 3�.6�9 2�0�.� ± ��.37 0.26963 ± 0.00�7

3×�0�� 3�.5�3 23�3.95 ± �0.6� 0.27757 ± 0.00�66

�×�0�2 3�.5�� 2250.� ± ��.69 0.295�5 ± 0.00�97

3×�0�2 3�.257 �7��.�5 ± �2.76 0.�9�05 ± 0.00�33

6×�0�2 3�.�26 �2��.� ±��.�0� 0.72�09 ± 0.007�3

�×�0�3 3�.09� 76�.�� ± 6.359 0.79306 ± 0.00672

2×�0�3 3�.037 267.65 ± 2.�56 0.7��5 ± 0.007��

TABLE I. Evolution of the peak centroid, integral intensity and FWHM with irradiation fluence of the (005)

XRD peak.



To explain the unexpected fast rate of Tc decrease

at very low fluences of irradiation, we consider

the effect of the SE in creation of point defects

around the amorphous track in YBCO matrix. The

estimated energy of these electrons however is

too low to create defects elastically. We invoke the

inelastic interaction of the low energy electrons

and show that YBCO offers an ideal platform where

SE can create defects by a process analogous to

dissociative recombination seen only in hydrogen

bonded molecules and organic medium [��]. The

point defects are the oxygen disorder in the CuO

chains of YBCO.

in situ low temperature X-ray diffraction study

The 2θ scan patterns of in situ low temperature

x-ray diffraction (XRD) spectra of YBCO film on

irradiation with 200 MeV Ag is shown in figure

3. The detailed values of peak position (2θ), peak

integrated intensity and the full width at half

maximum (FWHM) of (005) peak for all irradiation

fluences were given in TABLE I. The results are

summarized as follows: (i) The appearance of

only sharp (00l) peaks (l = 2 to 7) indicating

epitaxial nature of the film with grain orientation

along c-axis. (ii) No new peaks corresponding to

crystallographic planes other than (00l) up to the

highest fluence of irradiation (2×�0�3 ions cm-2)

appear. (iii) Spectra exhibit a sharp reduction in

(00l) peak intensity at low irradiation fluence (iv)

The (00l) peak shift towards lower angle with

increase of irradiation fluence, which is a sign of

expansion of the lattice parameter along the c-

axis (v) The full width at half maximum (FWHM)

of XRD peaks shows an incubation effect up to

�×�0�2 ions cm-2 and beyond which it increases.

Figure 2. The ρ(T) vs fluence in the mid fluence regime. To fit to the scale, the ρ(T) for the fluence 6.�7 ×

�0�2 ions cm-2 is divided by 3. Inset (a) shows the temperature dependence of resistance of YBCO films

irradiated at a fluence of � × �0�3 ions cm-2. Inset (b) shows the Tc vs fluence in the mid-fluence regime.

Figure 3 Evolution of low temperature (�9 K) in situ X-ray diffraction pattern of a YBa2Cu

3O

7-y thin film

with 200 MeV Ag ion irradiation fluence. In addition to (00l) peaks (l = 2 to 7) due to YBCO, there are

peaks due to the copper sample holder and the LaAlO3 substrate.

Fluence Peak Integrated intensity FWHM

(ion cm-2) centroid in degree

0 3�.6�3 266�.9 ± �6.� 0.2730� ± 0.002�2

�×�0�0 3�.635 2�77.37 ± �3.75 0.2752� ± 0.00�96

3×�0�0 3�.63� 2�32.0 ± �3.�2 0.27505 ± 0.00�95

�×�0�� 3�.6�9 2�0�.� ± ��.37 0.26963 ± 0.00�7

3×�0�� 3�.5�3 23�3.95 ± �0.6� 0.27757 ± 0.00�66

�×�0�2 3�.5�� 2250.� ± ��.69 0.295�5 ± 0.00�97

3×�0�2 3�.257 �7��.�5 ± �2.76 0.�9�05 ± 0.00�33

6×�0�2 3�.�26 �2��.� ±��.�0� 0.72�09 ± 0.007�3

�×�0�3 3�.09� 76�.�� ± 6.359 0.79306 ± 0.00672

2×�0�3 3�.037 267.65 ± 2.�56 0.7��5 ± 0.007��

TABLE I. Evolution of the peak centroid, integral intensity and FWHM with irradiation fluence of the (005)

XRD peak.



In the low fluence regime, the sharp decrease of Tc, Tc0

and integrated intensity of (00l) peaks with irradiation

fluence are due to creation of oxygen disorder in CuO

chains of YBCO by the swift heavy ion induced low

energy secondary electrons over a large range around

each amorphous ion latent track [��,�3]. The defect

creation is possible due to the crystal structure of YBCO,

which permits varying oxygen coordination of Cu

ions in the chains [�6] and offers an ideal situation for

trapping of the secondary electron and consequent

oxygen disorder in CuO chains inelastically. The

increase of FWHM beyond the �×�0�2 ions cm-2 is

due to the proximity of the strain region around the

amorphous latent tracks, which is the cause of the

evolution of the two-step superconducting transition

in the mid fluence regime.

conclUsion

In conclusion, the observation of integral intensity

of XRD peaks, Tc and T

c0 decrease at a much faster

rate with ion fluence is explained on the basis of

SHI induced secondary electrons, which create

oxygen disorder by electron capture process in the

CuO chains of a fully oxygenated YBCO structure.

The strain regions contribute to increase of FWHM

above a critical fluence of �0�2 ions cm-2. In this

fluence range, the radially strained region around

them amorphous latent tracks tends to overlap

and a two-step superconducting transition

evolves instead of a single transition.

acKnoWleDGements

The authors are thankful to the Pelletron group

of IUAC, New Delhi, for providing a good quality

scanned beam for irradiation. This work is

supported by the UFUP funding of IUAC, New

Delhi. One of the authors, R Biswal, would like

to thank the Council of Scientific and Industrial

Research (CSIR), Government of India, for the

award of SRF (F. No. 09/�73/(0�26)/200�/EMR-I).

references

[�] R. Simon and A. Smith, Superconductors: Conquering Technology’s New Frontier (Plenum, New York, �9��).

[2] M. K. Wu, R. J. Ashburn, C. J. Torng et al., Phys. Rev. Lett. 5� (�9�7) 90�.

[3] R. L. Fleischer, P. B. Price, R. M. Walker, J. Appl. Phys. 36 (�965) 36�5.

[�] A. Dunlop, D. Lesueur, J. Morillo et al., C. R. Acad. Sci. Ser. II 309 (�9�9) �277.

[5] A. Iwase, S. Sakaki, T. Iwata, T. Nihira, Phys. Rev. Lett. 5� (�9�7) 2�50.

[6] H. Dammak, A. Barbu, D. Lesueur, N. Lorenzelli, Philos. Mag. Lett. 67 (�993) 253.

[7] S. Klaumunzer, G. Schumacher, Phys. Rev. Lett. 5� (�9�3) �9�7.

[�] H. Bruining, Physics and Applications of Secondary Electron Emission (McGraw-Hill Book Company, Inc., New York, �95�).

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(2005) 05250�.

[�0] B. W. Veal, A. P. Paulikas, Hoydoo You et al., Phys. Rev.

B �2 (�995) 6305.

[��] R. Biswal, J. John, D. Behera, et al., Supercond. Sci.

Technol. 2� (200�) 0�50�6.

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[�3] R. Biswal, J. John, P. Mallick et al., J. Appl. Phys. �06

(2009) 0539�2.

[��] D. Bourgault, S. Bouffard, H. Toulemonde et al., Phys.

Rev. B 39 (�9�9) 65�9.

[�5] E. M. Jackson, B. D. Weaver, G. P. Summers et al. Phys.

Rev. Lett. 7� (�995) 3033.

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6 (�993) 359.



THEORETICAL STUDY OF THE EFFECT OF MAGNETIC FIELD IN CMR MANGANITES

Saswati Panda� and G.C. Rout2

�Trident Academy of Technology, F2/A, Chandaka Industrial Estate,Bhubaneswar -75�02�, India.

Email: [email protected] Matter Physics Group P. G. Deptt. of Applied Physics and Ballistics,

F. M. University, Balasore - 7560�9, India.

Abstract

We present a model calculation to study the magnetoresistivity (MR) through the

interplay between the magnetization and structural transitions for the manganite

systems. The manganite system is described by the double exchange model in presence

of core-spin in association with the static and dynamic band Jahn-Teller distortion

present in the eg band. The model Hamiltonian is solved using Zubarev’s Green’s

function technique and the resistivity is calculated using Drude-Lorentz formula.

Keywords: Colossal magneto-resistance; Jahn-Teller effect; Magnetization.

1 introduction

Mixed valent manganites with perovskite structure

having general formula R�−x

AxMnO

3 (where R is a

trivalent rare earth element like La, Pr, Nd and A is a

divalent alkaline earth element like Sr, Ca, Ba), have

been studied for almost 50 years. These materials

are insulators at high temperatures and poor

metals at low temperatures. This insulator to metal

transition is accompanied with a phase transition

from high temperature paramagnetic to low

temperature ferromagnetic phase. This transition

occurs around the transition temperature, Tc.

Application of magnetic field near Tc greatly

reduces the resistivity i.e. negative magneto-

resistance is observed. The magnetoresistance

arises from the spin-dependent scattering

process of conduction electrons. The electrical

resistivity (ρ) in the ferromagnetic region has

been studied by a numbers of authors[�, 2, 3].

In the low temperature region just below Tc, ρ

decreases rapidly with the decrease of T. For

Contributed Paper



T < 0.5Tc typically the variation is much less rapid,

but it is quite different from what is observed in

a metallic ferromagnet. Application of a magnetic

field (up to 6 Tesla) causes significant decrease in

the resistivity of La�−x

AxMnO

3 samples particularly

in the compositions 0.� < x < 0.5. These materials

are generally ferromagnetic with well-defined

Tcs. colossal magnetoresistance (CMR) close to

�00% has been observed in many polycrystalline

and single crystals of compositions La�−x

AxMnO

3,

but applied field is quite high (5-6 Tesla). In

La1-x

PbxMnO

3 high CMR is found around room

temperature or above [�].

The CMR effect is discovered by Jonker

and van Santen [5]. In �95� zener had proposed

the double exchange (DE) model to explain the

CMR phenomenon [6]. The DE model essentially

explains the behaviour of magnetoresistance

with respect to magnetization. Based on the study

of the RMn�−x

CrxO

3 system where isoelectronic

Cr3+ replacesMn�+, it has been shown recently

that DE is essential for the occurrence of CMR

in manganites [7]. However, A. J. Millis et. al. [�]

pointed out that, the DE model alone is not

enough to explain the CMR effect in manganites,

because DE produces wrong Tc by a large factor

and the resistivity that grows with reducing

temperature (insulating behaviour) even below Tc.

He claimed that Jhan-Teller (JT) effect is necessary

to explain the curvature of the resistivity close to

Tc. Millis et. al. [9, �0, ��, �2] argued that the physics

of manganites is dominated by the interplay

between a strong electron-phonon coupling and

the large Hund’s coupling effect that optimizes

the electronic kinetic energy by the generation of

a ferromagnetic phase. The spin-charge coupling

varies with temperature and composition, and

it increases across the metal insulator transition

[�3]. Recently Rout et. al. have shown that the

static JT distortion causes a IM transition near the

ferromagnetic Curie temperature in manganites

[��, �5]. The large value of the electron-phonon

coupling in manganites is clear in the regime

below x = 0.2, where a static J-T distortion plays

a key role in the physics of the material and a

dynamic J-T effect may persist at higher hole

densities [�6], without leading to long-range

order, but producing important fluctuations that

localize electrons by splitting the degenerate eg

levels at a given MnO6 octahedron.

The unusual properties of the CMR

effect are regarded as a co-operative phenomena

associated with a structural change due to a tiny

atomic displacement, competing with magnetic

interactions and charge fluctuations between

different valencies of manganese cations. In this

respect, Mn3+ orbitals show JT effect [�7] and

hence the degeneracy can easily be lifted by

lowering the crystal symmetry costing the lattice

distortion energies. Therefore it is believed that

the CMR should be the result of the local distortion

which is often defined as ”polarons”. The itinerary

of such polarons gives rise to the conduction. It

is well recognized that the JT interaction plays

a crucial role to determine the super-exchange

interactions in these transition metal oxides.

It is observed that there is charge ordering, in

addition to orbital ordering, in the manganese

oxide systems. More recently, Rout and co-workers

have reported the theoretical investigations of

the effect of charge ordering on the physical

properties like magnetization [��], velocity of

sound[�9], magnetic spin susceptibility [20] and

Raman spectra[2�] for the manganite system

(the calculation of resistivity is in progress). In the

present work we address the theoretical study of



the magnetoresistance in the manganese oxide

system in presence of JT distortion.

2 formalism

The electron Hamiltonian is

The four coupled Green’s functions are

(�)

where α = 0 − � and Eα (0) is given by

(5)

The self-energy of the electrons is given by

(6)

with Sα = (ω−Eα(k−q))(�+2νq)+ω

q(�−2nα). The four

quasi- particle energies in presence of JT distortion,

induced magnetism Mc in eg band and external

magnetic field B are given by Eα,k−q,σ = N0(k − q) −

μ − σB − (−�)αGe + σJMc. The term νq = [eωq/kBT −

�]−� is the Bose-Einstein distribution function and

nα is the electron occupation number. However, in

the present model calculation, ωq is taken as the

constant single frequency of Einstein model.

The electronic resistivity of the

manganite system can be found out from the

Drude-Lorentz formula ρ−� = ne2τ/m, where m

and e are the mass and charge of the electron, n

is the concentration of electron. The relaxation

time of electron (τ) due to electron-phonon

interaction is given by τ−� = Σατα−�. The τα (for α =

� − �) can be calculated from the imaginary part

of the self-energy of the four Green’s functions

Aα(k, ω) [see eqn. �]. The relaxation time τ is

an active function of the frequency (ω), the

magnetic field (B) and other physical parameters

of the manganite system. The resistivity of the

system is calculated numerically for different

parameters using the self-consistent values of

induced magnetization, Mc in eg band, the static

JT distortion, e and the magnetization Md in the

The Hamiltonian H0 describes the kinetic

energy of the eg electron in the first term, the JT

interaction in second term, the double exchange

interaction in third term, core-spin interaction in

fourth term and the kinetic energy of the core state

in the last term. Nkσ = (N

0(k) − μ − σµbB), N

dσ = Nd −

µ − σglµbBd and G, J, JH are the strength of electron

lattice interaction in presence of a tetragonal

distortion e, s−d exchange coupling constant and

Heisenberg coupling constant respectively. The

Hamiltonian describing the coupling of phonons

to the Jahn-Teller distorted eg band electrons

(�)

(2)

with f(q) as the dynamic electron-phonon

coupling constant and Aq = b

q + b†

−q is the phonon

displacement vector. Hp = Σ

q ω

qb†

qb

q is the free

phonon Hamiltonian, where ωq is the phonon

energy b†q (b

q) is the creation (annihilation)

operator of the phonons. So, the total Hamiltonian

is H = H0 + H

ep + H

p. The double time, single particle

electron Green’s functions are calculated using

the zubarev’s Green’s function technique [22] as

follows

(3)

�2



core t2g

band. The expressions for Mc, e and Md

are given below.

(7)

(�)

(9)

where f (y) = �/(� + ey/kBT ) is the Fermi distribution

function. The quasi-particle energies are written

as ω�, 2

= Nd − µ ± M

2R with M2

2R = M

2 2 + J2

H Sd2

and M2 = Bd − J

HMd. All the physical quantities are

scaled with respect to the conduction band width

(W). The dimensionless quantities are: ,

, , , , ,

, , and

3 results and Discussion

In order to study the temperature

dependence of the core-magnetization md and

the JT lattice strain e we have solved the eqns. (�)

and (9) self-consistently for a set of parameters like

the DE coupling g, the JT coupling g3 and the core-

spin coupling g2 for different external magnetic

fields. The results are shown in Fig.�. It is observed

that the increase of the external magnetic field

produces a tail at the Curie temperature thereby

destroying its robust character. Further the

external magnetic field suppresses the lattice

strain e in the interplay region, which in turn

enhances the induced magnetization (mc) in the

eg band electrons.

Fig.� The self-consistent plots of md, e, mc vs. t for

fixed values of g = 0.025, g2 = 0.033�, g

3 = 0.0�92 and

for different values of applied magnetic field b.

The calculated resistivity shows a

very high value between the low temperature

ferromagnetic metallic state and the high

temperature paramagnetic phase as shown in

Fig.2. On increasing external magnetic field to the

order of a few Tesla, the resistivity is suppressed

considerably in the insulating phase as observed

in the experimental measurements of the

manganite system.

��

�2

g = J W

g2 =

JH

Wg

3 =

G

Wt =

kBT

We =

e

Wg

� =

r0

f 2(q)

W

eq =

quF

W W=

ω W

p = ω

q

Wg=

η W .

Fig.2 The plot of resistivity ρ vs. t for fixed values of g, g

2, g

3 as taken in Fig.�, g

� = 0.�, e

q = 0.00�, p = 0.05,

W= 0.00�, g= 0.003 and for different values of applied magnetic field b.



References

[�] J. M. De Teresa et. al. Phys. Rev. B 5� ��7 (�996).[2] P. Schiffer et. al. Phys. Rev. Lett. 75 3336 (�995).[3] A. Urushibara et. al. Phys. Rev. B 56 ��03 (�995).[�] R. Mahendiran et. al. J. Phys. D: Appl. Phys. 2� �7�3

(�995).[5] G. H.Jonker and J. H. Van Santen Physica �6 337

(�950).[6] C. zener Phys. Rev. �� 0 (�95�); C. zener Phys. Rev.

�2 �03 (�95�).[7] R. Gundakaram et. al. J. Solid State Chem. �27 35�

(�996).[�] A.J. Millis, P. B. Littlewood and B. I. Shraiman Phys.

Rev. Lett. 7� 5�� (�955).[9] A. J. Millis, B. I. Shraiman and R. Mueller Phys. Rev.

Lett. 77 �75 (�996).[�0] A. J. Millis, B. I. Shraiman and R. Muller Phys. Rev. B 5�

53�9 (�996).[��] A. J. Millis nature 392 ��7 (�99�).[�2] A. J. Millis Phys. Rev. Lett. �0 �35� (�99�).

[�3] H. R¨oder, J. zhang and A. R. Bishop Phys. Rev. Lett. 76 �356 (�996).

[��] G. C. Rout, N. Parhi, S. N. Behera, Physica B �0� 23�5 (2009).

[�5] G. C. Rout, N. Parhi, S. N. Behera, Int. J. Mod. Phys.B 20 2093 (2006).

[�6] A. J. Millis, R. Muller and B. I. Shraiman Phys. Rev. B 5� 5�05 (�996).

[�7] J. B. Goodenough Phys. Rev. �00 56� (�955).[��] G. C. Rout, S. Panda and S. N. Behera, Physica B �0�

�273 (2009).[�9] G. C. Rout and S. Panda, J. Phys.: Condens. Matter 2�

��600� (2009).[20] G. C. Rout and S. Panda Solid State Comm. �50 6�3

(20�0).[2�] G. C. Rout, S. Panda and S. N. Behera J. Phys.: Condens.

Matter 22 376003 (20�0).[22] D. N. zubarev Sov. Phy. Usp. 3 320 (�960).



Abstract

The generation of nanostructures by energetic ion beams is highlighted. The energy

loss of the ions inside the materials medium takes the decisive role in forming the

nanostructures. Low energy ions loose energy by direct elastic knock-on process

and create vacancies, interstitials and even clusters of these defects finally getting

implanted in the target. All these defects help formation of nanoparticles embedded in

the substrate at controlled depth and density depending on ion energy and fluence. In

case of high energetic ions with energy shooting up to hundreds of million electron volt

(MeV), inelastic interaction of the projectile ion with the target electrons is the dominant

mode of energy loss. This so called electronic energy loss facilitates formation of

nanoparticles embedded in a matrix. Irradiation perpendicular to the target surface as

well as grazing incident ion beams have been used for the formation of nanostrucures.

The periodic nanoripples, equally spaced multiple nanodots are some of the examples

of nanostructures created by ion irradiation with grazing incidence ion beams on the

film surface. The unique attributes of low energy ions and high energy ions have also

utilized together to form monodispersed nanoparticles localized along ion tracks.

ENERGETIC ION BEAM: A TOOL FOR SYNTHESIS OF NANOSTRUCTURES

P. Mallick�,2,* and N. C. Mishra2,#

�P.G. Department of Physics, North Orissa University, Takatpur, Baripada-7570032P.G. Department of Physics, Utkal University, Vanivihar, Bhubaneswar-75�00�

*[email protected]; #[email protected]

Keywords: Ion beam; nanostructures; nanoparticles.

1. introduction:

In recent years nanostructured materials have

attracted a great deal of attention because of

their extremely small size and large surface-to-

volume ratio. These attributes of nanomaterials

have led to size dependent chemical and physical

properties, which are quite different from those of

bulk materials of the same chemical composition

[�]. These exotic properties thus emerging in

the nanoscale of the particle size have made

nanoparticle research as one of the hottest topics

in the present scenario due to their varieties of

technological applications. The new technology

which emerges with nanoparticles is known as

nanotechnology. The nanoparticles are generally

defined as small solid objects whose physical

dimension lies in the range from a few nm to

about hundred nm. Their size is sufficiently large to

represent the crystalline properties but still small

enough where significant differences in chemical,

structural, electrical and magnetic properties

from their bulk counterparts are observed. These

unusual properties are seen in nanoparticles due

to their extremely large surface to volume ratio

and quantum confinement effect.

Nanostructures can be synthesized

by various physical (sputtering, pulsed laser

deposition, electron-beam evaporation etc.) and

chemical (atomic layer epitaxy, sol–gel, spray

pyrolysis, anodic deposition etc.) methods by

following two basic approaches such as bottom

up and top down. In bottom up approach, the

atoms are brought together to form particles

of nanometric dimension whereas in top down

approach, large size grains are broken to form

nanodomains. Ion beam based synthesis method

utilizes both the approaches for generation of

nanostructure.

In this paper, we discuss the interaction of

energetic ions with materials medium in different

energy regimes. The possibilities of synthesis of

nanostructures with different ion energies are

reviewed.

2. ion-matter interaction:

While traversing through the materials medium,

energetic ions transfer high localized density of

the energy to the target medium. The solid may

receive for a very short time (~�0−�7 to �0−�5 s)

within a very tiny volume (~�0−�7 to �0−�6 cm3) the

same energy density which else is only found in

the vicinity of an exploding hydrogen bomb by

the impact of just one energetic heavy ion [2].

The energy deposited by the energetic ion beam

into materials medium is commonly described by

the “stopping power” which is the measure of the

energy transfer per unit path length of a projectile

along its trajectory. The energy of the ion is

transferred to the solid almost instantaneously

into a highly localized volume of nm-dimensions

in two nearly independent processes: (i) nuclear

energy loss (Sn) and (ii) electronic energy loss (S

e).

Finally the projectile ion gets implanted when

it loses all its energy in the material medium.

Depending on the energy, the ion beams are

mainly divided in to two categories: (i) low energy

ions (LEI) and (ii) swift heavy ions (SHI). The low

energy ions have energy in the range from some

keV to a few MeV and the ion with energy some

tens of MeV and beyond is considered as swift

heavy ion.

In the keV range of ion energy, the Sn

induced processes dominate and lead to creation

of atomic size point defects and clusters of

defects in the target. When the velocity of the ion is

comparable to the Bohr velocity of the electron, the

Se induced processes lead to coherent excitation and

ionization of electrons along the ion path. When Se

exceeds a materials dependent threshold value Seth

,

a trail of defects or ammorphized latent tracks are

expected to be implanted in the material along the

ion path [3]. Track registration is a consequence of

extremely intense solid state excitation generated

by the SHI along its path within a very short

interval of time. This process thus involves driving

the system far from equilibrium state in a highly

Contributed Paper



Abstract

The generation of nanostructures by energetic ion beams is highlighted. The energy

loss of the ions inside the materials medium takes the decisive role in forming the

nanostructures. Low energy ions loose energy by direct elastic knock-on process

and create vacancies, interstitials and even clusters of these defects finally getting

implanted in the target. All these defects help formation of nanoparticles embedded in

the substrate at controlled depth and density depending on ion energy and fluence. In

case of high energetic ions with energy shooting up to hundreds of million electron volt

(MeV), inelastic interaction of the projectile ion with the target electrons is the dominant

mode of energy loss. This so called electronic energy loss facilitates formation of

nanoparticles embedded in a matrix. Irradiation perpendicular to the target surface as

well as grazing incident ion beams have been used for the formation of nanostrucures.

The periodic nanoripples, equally spaced multiple nanodots are some of the examples

of nanostructures created by ion irradiation with grazing incidence ion beams on the

film surface. The unique attributes of low energy ions and high energy ions have also

utilized together to form monodispersed nanoparticles localized along ion tracks.

ENERGETIC ION BEAM: A TOOL FOR SYNTHESIS OF NANOSTRUCTURES

P. Mallick�,2,* and N. C. Mishra2,#

�P.G. Department of Physics, North Orissa University, Takatpur, Baripada-7570032P.G. Department of Physics, Utkal University, Vanivihar, Bhubaneswar-75�00�

*[email protected]; #[email protected]

Keywords: Ion beam; nanostructures; nanoparticles.

1. introduction:

In recent years nanostructured materials have

attracted a great deal of attention because of

their extremely small size and large surface-to-

volume ratio. These attributes of nanomaterials

have led to size dependent chemical and physical

properties, which are quite different from those of

bulk materials of the same chemical composition

[�]. These exotic properties thus emerging in

the nanoscale of the particle size have made

nanoparticle research as one of the hottest topics

in the present scenario due to their varieties of

technological applications. The new technology

which emerges with nanoparticles is known as

nanotechnology. The nanoparticles are generally

defined as small solid objects whose physical

dimension lies in the range from a few nm to

about hundred nm. Their size is sufficiently large to

represent the crystalline properties but still small

enough where significant differences in chemical,

structural, electrical and magnetic properties

from their bulk counterparts are observed. These

unusual properties are seen in nanoparticles due

to their extremely large surface to volume ratio

and quantum confinement effect.

Nanostructures can be synthesized

by various physical (sputtering, pulsed laser

deposition, electron-beam evaporation etc.) and

chemical (atomic layer epitaxy, sol–gel, spray

pyrolysis, anodic deposition etc.) methods by

following two basic approaches such as bottom

up and top down. In bottom up approach, the

atoms are brought together to form particles

of nanometric dimension whereas in top down

approach, large size grains are broken to form

nanodomains. Ion beam based synthesis method

utilizes both the approaches for generation of

nanostructure.

In this paper, we discuss the interaction of

energetic ions with materials medium in different

energy regimes. The possibilities of synthesis of

nanostructures with different ion energies are

reviewed.

2. ion-matter interaction:

While traversing through the materials medium,

energetic ions transfer high localized density of

the energy to the target medium. The solid may

receive for a very short time (~�0−�7 to �0−�5 s)

within a very tiny volume (~�0−�7 to �0−�6 cm3) the

same energy density which else is only found in

the vicinity of an exploding hydrogen bomb by

the impact of just one energetic heavy ion [2].

The energy deposited by the energetic ion beam

into materials medium is commonly described by

the “stopping power” which is the measure of the

energy transfer per unit path length of a projectile

along its trajectory. The energy of the ion is

transferred to the solid almost instantaneously

into a highly localized volume of nm-dimensions

in two nearly independent processes: (i) nuclear

energy loss (Sn) and (ii) electronic energy loss (S

e).

Finally the projectile ion gets implanted when

it loses all its energy in the material medium.

Depending on the energy, the ion beams are

mainly divided in to two categories: (i) low energy

ions (LEI) and (ii) swift heavy ions (SHI). The low

energy ions have energy in the range from some

keV to a few MeV and the ion with energy some

tens of MeV and beyond is considered as swift

heavy ion.

In the keV range of ion energy, the Sn

induced processes dominate and lead to creation

of atomic size point defects and clusters of

defects in the target. When the velocity of the ion is

comparable to the Bohr velocity of the electron, the

Se induced processes lead to coherent excitation and

ionization of electrons along the ion path. When Se

exceeds a materials dependent threshold value Seth

,

a trail of defects or ammorphized latent tracks are

expected to be implanted in the material along the

ion path [3]. Track registration is a consequence of

extremely intense solid state excitation generated

by the SHI along its path within a very short

interval of time. This process thus involves driving

the system far from equilibrium state in a highly

Contributed Paper



localized region, which cannot be achieved by any

other technique [�].

Two independent models exit to

describe the formation of ion tracks in the

materials medium such as (i) Coulomb explosion

(explosion-like repulsion of the ionized atoms

along the ions path) [5,6] and (ii) thermal spike

model [7-�0]. Coulomb explosion model predicts

that the electrons around the ion path move

away radially after receiving energy from the

projectile ion leaving behind only the positively

charged ions along the projectile ion path. The

repulsive interaction between these ions along

the projectile path leads to bond breaking as a

result of which the materials along the ion path

get damaged. Thermal spike model predicts that

the energy initially transferred to the electrons is

finally transferred to the lattice atom, which can

lead to a local temperature increase. The thermal

spike model thus predicts confinement of heat

energy within the small volume along the ion

path. If the consequence temperature rise exceeds

the melting temperature of the target, the target

melts in this confined volume.

In both the cases, due to large electronic

energy loss of the ion, a cylindrical amorphized

zone of some nm in diameter can form along

the ions path. Energy dissipation into the cold

surrounding resulted in rapid solidification within

some tens to some hundreds of picoseconds,

and depending on the material, leave behind a

defect-rich or even amorphous track of typically

�0 nm in diameter and some μm length [��]. A

preferential chemical etching along the defective

regions or ion track can be exploited to produce

high-precision filter membranes [6,�2,�3], drug

release devices [�3,��], isolated nanopores for

single biomolecule molecule detection [�5], and

nanopore ion pumps [�6]. The electronic devices

such as transistors, resistors and transformers can

be constructed out of these nanopores by filling

appropriate materials [�7,��].

Energetic ions are an excellent tool for

the creation of nano-structures on the surface or

in the near-surface region of a solid [��]. Ion beams

in the past have played a very crucial role in the

formation, modification and characterization of

nanoparticles. Utilizing the ion energy, fluence and

materials medium one can synthesis nanoparticle

both by SHI and LEI. Different possibilities of

synthesizing nanostructures with energetic ion

beam are discussed in the following sections.

3.1. synthesis of nanostructure by low energy

ions (lei):

The low energy ions (LEI) are utilized for synthesis

of nanostructures either by ion bombardment or

by ion implantation method. In this process the

generation of nanostructures is confined mainly

to the surface or near surface region only. For the

ion implanted case, the implanted ion takes the

important role for the formation of final product.

3.1.1. Synthesis of nanostructures by LEI

bombardment:

The generation of surface nanostructures has

been achieved by bombarding the materials

surface with LEI. The creation of periodic arrays

of nanoripples and nanodots by sputtering with

low-energy ions in metals and semiconductors

has been reported by various groups [�,�9,20]. The

surface relief induced by sputtering under certain

conditions can take the shape of ripples similar to

those created by the wind on the sea or the sand



[�]. The nanoripples generated at the surfaces

can be further used as a template for growing

nanowires. The surface structuring of InSb by the

�-3 MeV Au ion bombardment is explained on the

basis of ion beam induced sputtering [�9]. SnO2

films bombareded with 250 keV Xe+ ion lead to

the generation of nanodots. The size and shape of

nanodots formed with Xe+ ion bombardment were

different for different substrate. The generation of

defects under Xe+ ion bombardment facilitates

the growth of SnO2 nanodots [20].

3.1.2. Synthesis of nanoparticles by ion

implantation:

In this process the suitable substrate material

is implanted by the projectile ion. Ordinarily

the range of the LEI is less as compared to the

substrate thickness so the ions will be implanted

in the near surface region. Then the implanted

material is annealed at high temperature and the

nanoparticles form due to phase segregation.

If the implanted ion and matrix are immiscible,

the thermal annealing leads to the formation of

embedded nanoparticle of the implanted ions.

The unique features of ion implantation method

over other synthesis methods are

(i) Ion implantation overcomes restrictions

imposed by chemical incompatibility of

dopants and the host matrix faced by

chemical routes. Almost any substrate can

be doped with any ion.

(ii) The formation of nanoparticles is of

extreme chemical purity (including isotope

selection).

(iii) This can be used for submicron pattern

resolution i.e. ion implantation can be carried

out with masks or with finely focussed beams

( �0 nm diameter).

(iv) Ion implantation allows well dispersed

nanoparticles embedded in a matrix. The

size and density of nanoparticles can be

controlled by controlling ion fluence and

annealing temperature.

(v) This allows to control the location of

nanoparticle formation beneath the surface

by controlling the energy and hence range

of the projectile ion.

(vi) Diffusion of implantated species can be

mediated through irradiation induced

vacancies and interstials i.e. radiation

enhanced diffusion.

There are some limitations of ion implantation

method and care must be taken to avoid unwanted

reactions between nanocrystals and substrates

and the atomic displacement damages caused

by energetic ions. If the ions are implanted at low

energies, their depth profile intersects the surface

so that incoming ions may sputter previously

implanted ones. if the ions are implanted at higher

energies (to overcome problem of sputtering of

implanted atoms), the duration of the implantation

may be prohibitive because the concentration at

the mean range decreases in inverse proportion

to the profile width, which varies almost in

proportion to the ion energy [�].

3.2. synthesis of nanostructures by swift heavy

ions (shi):

Swift heavy ion irradiation has been utilized to

generate nanostructures in the surface as well as

along the ion path while traversing in the materials

medium. In this process the role of electronic

energy loss is important. The ion species do not

take the decisive role in forming the final material



as these ions travel much dipper into the substrate

after crossing the film thickness (material).

SHI instantaneously deposit a huge

amount of energy in the nano scale regions which

results into a nm-scale zone of extreme non-

equilibrium conditions with high atomic mobility

and reduced density. Energy dissipation into the

cold surrounding then results in rapid solidification

in picoseconds time domain, and depending on

the material, leave behind a columnar defect or

even amorphous track along the ion path. Surface

instability caused by the stresses generated

in the ion track and subsequent anisotropic

deformation by SHI bombardment (‘‘hammering

effect’’, since the material expands perpendicular

and shrinks along the beam direction as if treated

with a hammer) led to the generation of surface

nanostructure [��]. The generation and processing

of complex nano-structures is realized from thin

NiO-films taking advantage of a surface instability

caused by the stresses generated in the ion track,

and utilizing the hammering effect [2�]. For

example, periodic pattern of NiO walls (~ �00–200

nm thickness and � μm height and distance) have

been formed on the surface of �30 nm thick NiO

layer grown on SiO2 when irradiated with 230 MeV

Xe ions at a tilt angle of 750 [��].

The formation of cylindrical ion track

of radius ~ � nm is formed in SnO2 matrix under

the bombardment of �00 MeV Ag ions, which

acts as the nucleating centre for the growth of

uniform size (radius ~ � nm) nanocrystals of SnO2

inside the ion track [22]. Swift heavy ion induced

nucleation and growth processes of nanocrystals

leads to synthesis of narrow size distributed

nanocrystals in the SnO2 matrix. The formation of

uniform size nanoparticles of NiO at the tip of the

ion track has also been reported [23]. Deposition

of huge amount of energy by the SHI along the

ion path results into the molten ion track which

experiences a compressive stress due to thermal

expansion. Large stress gradients accelerate the

molten material from the track region toward

the surfaces and results into the formation of

nanoparticles (7-9 nm in diameter) at the tip of

the ion tracks [23].

The formation of multiple, equally spaced

dots of SrTiO3, each separated by a few tens of

nanometers have been created after irradiation

of the surface by SHI under grazing angles of a

few degrees with respect to the surface plane. The

number of dots and their spacing can be controlled

by controlling the incident angle [2�]. SHI irradiation

on SiOx led to the phase separation of Si and silica

under dense electronic excitation due to reduction

process. As the SHI irradiation causes the evolution

of oxygen from the film and a phase separation

changes the system into Si nanocrystal and a more

stoichiometric SiO2 matrix [25].

3.3. synthesis of nanostructures by using both

lei and shi:

The synthesis of nanostructures utilizing both the

role of LEI and SHI can be achieved. The basic idea

is to control the size distribution of nanocrystals

which can be formed by ion implantation and

subsequent SHI irradiation. The SHI irradiation

led to the generation of cylindrical ion track or

defective regions which may act as the nucleating

centre for the growth the uniform size nanocrystals

of size about the size of ion track. Mohanty et

al. [26] have reported that the formation of Si

nanoparticle and narrow size distribution of the

particles could be achieved by irradiating the Si

ion implanted silica with 70 MeV Si ions.



4. conclusion:

The applicability of energetic ion beam for the

synthesis of nanostructures has been discussed

with some of the important results in this

line of study has been outlined and the basic

principles behind these results are discussed.

For example, the periodic nanoripples surface

can be synthesized with the help of low energy

ion beam. Both nanodots and buried layer can

be synthesized by ion implantation method. The

multiple nanodots separated by equal spacing

can be created by SHI irradiation with grazing

incidence. Ion implantation combined with swift

heavy ion irradiation also used for the synthesis of

nanostructures.

references:

[� D.K. Avasthi and J.C. Pivin, Curr. Sci. 9�, 7�0 (20�0) (and references therein).

[2] D. Fink and L.T. Chadderton, Brazilian J. Phys. 35, 735 (2005)

[3] J. Vetter, R. Scholz, D. Dobrev and L. Nistor, Nucl. Instrum. Methods Phys. Res. B ��, 7�7 (�99�) (and references therein).

[�] P. Mallick, C. Rath, Jai Prakash, D.K. Mishra, R.J. Choudhary, D.M. Phase, A. Tripathi, D.K. Avasthi, D. Kanjilal and N.C. Mishra, Nucl. Instrum. Methods Phys. Res. B 26�, �6�3 (20�0).

[5] R.L. Fleischer, P.B. Price and R.M. Walker, J. Appl. Phys. 36 (�965) 36�5.

[6] R.L. Fleischer, P.B. Price and R.M. Walker, Nuclear Tracks in Solids, University of California Press, �975.

[7] F. Seitz and J.S. Koehler, Solid State Phys. 2 (�956) 305.

[�] z.G. Wang, Ch. Dufor, E. Paumier, F. Pawlak and M. Toulemonde, J. Phys.: Condens. Matter 6 (�99�) 6733.

[9] M. Toulemonde, Ch. Dufor, z.G. Wang and E. Paumier, Nucl. Instrum. Methods Phys. Res. B �22 (�996) 26.

[�0] M. Toulemonde, J.M. Costantini, Ch. Dufor, A. Meftah, E. Paumier and F. Studer, Nucl. Instrum. Methods Phys. Res. B ��6 (�996) 37.

[��] W. Bolse, Nucl. Instrum. Methods Phys. Res. B 2��, � (2006) (and references therein).

[�2] J.-H. zollondz and A. Weidinger, Nucl. Instrum. Methods Phys. Res. B 225, �7� (200�).

[�3] h t t p : / / w w w. w h a t m a n . p l c . u k / p r o d u c t s /nuclepore/index.htm

[��] R. Spohr, Ion Tracks and Microtechnology (Vieweg, Braunschweig, �990).

[�5] A. Mara, z. Siwy, C. Trautmann, J. Wan and F. Kamme, Nano Lett. �, �97 (200�).

[�6] z. Siwy and A. Fulinski, Phys. Rev. Lett. �9, �9��03 (2002).

[�7] J. Chen and R. K.nenkamp, Appl. Phys. Lett. �2, �7�2 (2003).

[��] D. Fink, P.S. Alegaonkar, A.V. Petrov, A.S. Berdinsky, V. Rao, M. Müller, K.K. Dwivedi, and L.T. Chadderton, Radiat. Meas. 36, 605 (2003).

[�9] A.G. Perez-Bergquist, K. Li, Y. zhang and L. Wang, Nanotech. 2�, 325602 (20�0)

[20] T. Mohanty, Y. Batra, A. Tripathi, and D. Kanjilal, J. Nanosci. Nanotechnol. 7, � (2007)

[2�] W. Bolse, B. Schattat, and A. Feyh, Appl. Phys. A 77, �� (2003).

[22] T. Mohanty, P. V. Satyam and D. Kanjilal, J. Nanosci. Nanotechnol. 6, �(2006)

[23] B. Schattat, W. Bolse, S. Klaumünzer, I. zizak and R. Scholz, Appl. Phys. Lett. �7, �73��0 (2005).

[2�] E. Akcöltekin, T. Peters, R. Meyer, A. Duvenbeck, M. Klusmann, I. Monnet, H. Lebius and M. Schleberger, Nature Nanotech. 2, 290 (2007).

[25] P.S. Chaudhari, T.M. Bhave, D. Kanjilal and S. Bhoraskar, J. Appl. Phys. 93, ��6 (2003).

[26] T. Mohanty, A. Pradhan, S. Gupta and D. Kanjilal, Nanotech. �5, �620 (200�).



MICROSCOPIC THEORY OF ULTRASONIC ATTENUATION IN CHARGE AND SPIN ORDERED CUPRATE SYSTEMS

G. C. Rout�∗ and S. K. Panda2

�∗Condensed Matter Physics Group, P. G. Dept. of Applied Physics and Ballistics,

F. M. University, Balasore, India-756 0�9. 2 K. D. Science College , Pochilima , Hinjilicut-76� �0� , Ganjam , Orissa , India.

Corresponding author, Email: [email protected], Tel: +9�-99379��69�

Abstract

In this communication we report a model study of the ultrasonic attenuation in the

high-Tc cuprate systems in normal state. The model consists of the charge density wave

(CDW) and spin density wave (SDW) interactions in presence of doping concentrations.

The phonons are assumed to be coupled to the conduction electron density in

harmonic approximation. The phonon Green’s function is calculated by using Zubarev’s

technique of Green’s function, the imaginary part of which is proportional to ultrasonic

attenuation coefficient. The frequency and temperature dependent attenuation

coefficient is calculated numerically by varying the different model parameters of the

system like electron-phonon coupling, CDW coupling and the SDW coupling. The results

are discussed to explain the experimental observations of different levels of doping and

temperatures. This model calculation outlines how to calculate the individual CDW and

SDW order parameters from the observed experimental peak positions.

Keywords: SDW; CDW ; High-Tc superconductors ; Ultrasonic attenuation.

1 introduction.

Ultrasonic measurements have been of great

importance in investigating the bulk properties of

materials arising due to the lattice instabilities and

phase transitions. A number of structural anomalies

signifying the lattice instabilities and phase

transitions in high temperature superconductors

around the critical temperatures Tc. Apart from

the attenuation peak in the vicinity of the critical

temperatures Tc, there is also an attenuation peak

around 200K[�]. The measurements on show that

the attenuation peaks at Tc and above 200K are

associated with the interaction of sound waves

with the excitations in the CuO2 planes. However,

the peak around Tc is observed to shift to high

temperatures with increasing ultrasonic frequency

indicating the characteristic of a thermally activated

relaxation peak. The attenuation measurements

on Bi2Sr

2CaCu

2O

8 show an attenuation peak

around 250K indicating the character of a phase

transition rather than a relaxation. Understanding

the normal state anomalous behavior of the high-

Tc superconductors remains one of the major

challenges posed by these materials. In the under-

doped region, a well defined feature is the opening

of a pseudo-gap at the characteristic temperature

T*(T* >Tc) A few microscopic theories of ultrasonic

attenuation has been reported to explain the

experimental data for the copper oxide systems.

Earlier Rout and co-workers have reported a

theoretical model for ultrasound study[2, 3],

Raman spectra [�, 5] on the basis of a model study

displaying the interplay of the antiferromagnetism

and hybridization. In the present work, we

consider a model study for ultrasonic attenuation

describing the interplay of charge density wave

(CDW) and spin density wave (SDW) interactions

in high-Tc superconductors. We consider here the

model study to describe the normal phase of the

system. Here the insulating CDW interaction is

assumed to play the role of pseudo-gap which is

more prominent in the under-doped region for the

system. The organization of the present work is as

follows. The formalism for the model calculation is

presented in section-2. The results and discussion

and finally the conclusion are given in section-3.

2 formalism

In high-Tc systems, there exists antiferromagnetic

spin order with commensurate wave vector Q in

Neutron scattering[6] and Raman scattering[7]

measurements. Due to low dimensionality of the

high-Tc systems, there exists nesting of the Fermi

surface leading to the establishment of the spin

density wave (SDW) phase. The electronphonon

interaction in two dimensional high-Tc system

gives rise to the charge order CDW state with

an interaction strength V1 = 2g2

Q /Nω

Q, where g

Q

is the electronphonon interaction with a nesting

vector Q. Based on our earlier model study[�, 9]

the mean-field Hamiltonian can be written as

H0 = ∑(∈

0(k) - μ)c†

k,σ ck,σ + D

c ∑ c†

k+Q, σck,σ

k,σ k,σ

+ Ds ∑ (c†

k+Q, ↑ ck,↑ - c

†k+Q, ↓ c

k,↓ ) (�) k

where Dc(D

s) are the CDW(SDW) order parameters

and c†k6

(ck,6

) is the creation and annihilation

electron operators. In order to study the elastic

properties, we consider the phonon coupling to the

conduction band within harmonic approximation

with the Hamiltonian

H� = ∑ ƒ(q) c$

k+q, σ c

k, σ A

q + ∑ ω

q b$

qb

q (2)

k+q, σ q

where Aq=(b†

q+b†

−q) with b†

q(b

q) is the

creation(annihilation) operator of the phonon

with frequency ωq and wave vector q. The retired

phonon Green’s function is defined as Dq,q′(t, t′) =

−iQ(t, t′) < [Aq(t); A

q′(t′)] >. Using total Hamiltonian,

the Green’s function[6] takes the general form

D

q,q′(ωq) =

ωq [ω2 - ω2

q - ∑ (ω,q)]-�

π

where the phonon self-energy reduces to ∑(ω, q) =

�πωqχ

q,q(ω). The ultrasonic attenuation co-efficient

α(ω, T) for ultrasonic sound waves of frequency ω,

phonon wave vector q at temperature T is given

by the imaginary part of the phonon selfenergy.

Mathematically, it is written as

α(ω,T, q) = - [ � �πImχqq

(ω,T,q)]

ωq

where χqq

(ω, T, q) is the electron response function

Contributed Paper



MICROSCOPIC THEORY OF ULTRASONIC ATTENUATION IN CHARGE AND SPIN ORDERED CUPRATE SYSTEMS

G. C. Rout�∗ and S. K. Panda2

�∗Condensed Matter Physics Group, P. G. Dept. of Applied Physics and Ballistics,

F. M. University, Balasore, India-756 0�9. 2 K. D. Science College , Pochilima , Hinjilicut-76� �0� , Ganjam , Orissa , India.

Corresponding author, Email: [email protected], Tel: +9�-99379��69�

Abstract

In this communication we report a model study of the ultrasonic attenuation in the

high-Tc cuprate systems in normal state. The model consists of the charge density wave

(CDW) and spin density wave (SDW) interactions in presence of doping concentrations.

The phonons are assumed to be coupled to the conduction electron density in

harmonic approximation. The phonon Green’s function is calculated by using Zubarev’s

technique of Green’s function, the imaginary part of which is proportional to ultrasonic

attenuation coefficient. The frequency and temperature dependent attenuation

coefficient is calculated numerically by varying the different model parameters of the

system like electron-phonon coupling, CDW coupling and the SDW coupling. The results

are discussed to explain the experimental observations of different levels of doping and

temperatures. This model calculation outlines how to calculate the individual CDW and

SDW order parameters from the observed experimental peak positions.

Keywords: SDW; CDW ; High-Tc superconductors ; Ultrasonic attenuation.

1 introduction.

Ultrasonic measurements have been of great

importance in investigating the bulk properties of

materials arising due to the lattice instabilities and

phase transitions. A number of structural anomalies

signifying the lattice instabilities and phase

transitions in high temperature superconductors

around the critical temperatures Tc. Apart from

the attenuation peak in the vicinity of the critical

temperatures Tc, there is also an attenuation peak

around 200K[�]. The measurements on show that

the attenuation peaks at Tc and above 200K are

associated with the interaction of sound waves

with the excitations in the CuO2 planes. However,

the peak around Tc is observed to shift to high

temperatures with increasing ultrasonic frequency

indicating the characteristic of a thermally activated

relaxation peak. The attenuation measurements

on Bi2Sr

2CaCu

2O

8 show an attenuation peak

around 250K indicating the character of a phase

transition rather than a relaxation. Understanding

the normal state anomalous behavior of the high-

Tc superconductors remains one of the major

challenges posed by these materials. In the under-

doped region, a well defined feature is the opening

of a pseudo-gap at the characteristic temperature

T*(T* >Tc) A few microscopic theories of ultrasonic

attenuation has been reported to explain the

experimental data for the copper oxide systems.

Earlier Rout and co-workers have reported a

theoretical model for ultrasound study[2, 3],

Raman spectra [�, 5] on the basis of a model study

displaying the interplay of the antiferromagnetism

and hybridization. In the present work, we

consider a model study for ultrasonic attenuation

describing the interplay of charge density wave

(CDW) and spin density wave (SDW) interactions

in high-Tc superconductors. We consider here the

model study to describe the normal phase of the

system. Here the insulating CDW interaction is

assumed to play the role of pseudo-gap which is

more prominent in the under-doped region for the

system. The organization of the present work is as

follows. The formalism for the model calculation is

presented in section-2. The results and discussion

and finally the conclusion are given in section-3.

2 formalism

In high-Tc systems, there exists antiferromagnetic

spin order with commensurate wave vector Q in

Neutron scattering[6] and Raman scattering[7]

measurements. Due to low dimensionality of the

high-Tc systems, there exists nesting of the Fermi

surface leading to the establishment of the spin

density wave (SDW) phase. The electronphonon

interaction in two dimensional high-Tc system

gives rise to the charge order CDW state with

an interaction strength V1 = 2g2

Q /Nω

Q, where g

Q

is the electronphonon interaction with a nesting

vector Q. Based on our earlier model study[�, 9]

the mean-field Hamiltonian can be written as

H0 = ∑(∈

0(k) - μ)c†

k,σ ck,σ + D

c ∑ c†

k+Q, σck,σ

k,σ k,σ

+ Ds ∑ (c†

k+Q, ↑ ck,↑ - c

†k+Q, ↓ c

k,↓ ) (�) k

where Dc(D

s) are the CDW(SDW) order parameters

and c†k6

(ck,6

) is the creation and annihilation

electron operators. In order to study the elastic

properties, we consider the phonon coupling to the

conduction band within harmonic approximation

with the Hamiltonian

H� = ∑ ƒ(q) c$

k+q, σ c

k, σ A

q + ∑ ω

q b$

qb

q (2)

k+q, σ q

where Aq=(b†

q+b†

−q) with b†

q(b

q) is the

creation(annihilation) operator of the phonon

with frequency ωq and wave vector q. The retired

phonon Green’s function is defined as Dq,q′(t, t′) =

−iQ(t, t′) < [Aq(t); A

q′(t′)] >. Using total Hamiltonian,

the Green’s function[6] takes the general form

D

q,q′(ωq) =

ωq [ω2 - ω2

q - ∑ (ω,q)]-�

π

where the phonon self-energy reduces to ∑(ω, q) =

�πωqχ

q,q(ω). The ultrasonic attenuation co-efficient

α(ω, T) for ultrasonic sound waves of frequency ω,

phonon wave vector q at temperature T is given

by the imaginary part of the phonon selfenergy.

Mathematically, it is written as

α(ω,T, q) = - [ � �πImχqq

(ω,T,q)]

ωq

where χqq

(ω, T, q) is the electron response function

Contributed Paper



for long wave longitudinal phonons. The response

function is a two particle Green’s function which

is calculated from the electronic Hamiltonian

in absence of electron-phonon interaction. The

physical quantities involved in the calculation are

made dimensionless by dividing them by hopping

integral 2t0. They are

z� =

Dc ; z

2 =

Ds ; g

�=N (O)V

�; g

2 = N (O)U;

t =

kBT

2t0 2t

0 2t

0

ω = ω ;

p= ω

c = ω

; e= η

; qƒ = qu

F

ω0 2t

0 2t

0 2t

0 2t

0

3 results and Discussion

The CDW coupling (g� = 0.055) and SDW coupling

(g2 = 0.06�) are so chosen that the transition

temperature of CDW phase is greater than that of

the SDW (i.e tCDW

= 0.056, tSDW

= 0.0� in absence

of doping). The CDW and SDW phases co-exist for

temperature t < tSDW

. For the given values of (z�)

and (z2) at a fixed temperature, the attenuation

coefficient is calculated numerically.

Fig. 1 The plot of vs ω for CDW gap parameter

z1=0.04927, SDW gap parameter z

2=0.04437,

temperature t=0.01, bare phonon frequency p=0.1

for EP couplings s=0.155, 0.17, 0.20.

The Fig.� shows ultrasound energy dependence of

the ultrasonic attenuation co-efficient for different

electron-phonon (EP) couplings. For coupling

constant s = 0.�55, we observe two absorption

Fig. 2 The plot of α vs ω for z1=0.04927, z

2=0.04437,

phonon energy qf=0.001, EP coupling s=0.15 for

temperatures t=0.03, 0.04, 0.05.

peaks at energies ω� . 2.� and ω

2 . 0.�5 for the

optical phonon at q= 0. The reduced energy ω is

defined as ω = ω/ω0 = c/p, where c is the reduced

frequency and p is the bare phonon frequency.

Corresponding to the given value p = 0.�, we

observe two ultrasonic peaks i.e. high energy peak

at c� = 0.2� and low energy peak at c

2 = 0.0�5. From

the poles of the Green’s function, we expect two

ultrasonic peaks with energies 2(z� +z

2 ) and 2(z

� −

z2). For temperature t=0.0�, the gap parameters are

found to be (z�) = 0.0�97 and (z2) = 0.0��37. Hence

the calculated peak value should appear at 2(z� +

z2 ) = 0.�� and 2(z

� − z

2)=0.0��. These calculated

values are slightly less than the observed values of

(c�) and (c

2) which are enhanced due to the effect

of the electron-phonon interaction. It is concluded

that the magnitudes of the order parameters (z�)

and (z2) can be calculated from the observed peak

positions in the ultrasound measurements. It is

found that the position of higher energy peak is

shifted to still higher energies and the position of

the low energy peak is shifted to lower energies

due to the electron-phonon interaction present

in the system. The electron-phonon coupling, s

= 0.�55 is comparable to s = 0.�� - 0.�5 obtained

from other theoretical calculations reported.

Further, the ultrasonic absorption increases

with the increase of EP coupling resulting in the

increase of the height of the resonance peaks.



The temperature dependence of ultrasonic

attenuation is shown in Fig.2. With the increase

of temperature, the high energy peak at ω� shifts

to lower energies and the low energy peak at !˜2

shifts to higher energies. Further, spectral height

at energy ω� is suppressed with increase of

temperature, while the spectral height at energy ω2

is enhanced with increase of temperature. It is seen

from temperature dependence of gap parameters

(z� and z

2) that the magnitudes of both the gaps

decrease with the increase of temperature. As a

result, the peak at ω� decreases because the value

2(z� +z

2) decreases with increase of temperature.

The peak position at ω2 increases with increase

of temperature, because the effective energy

2(z� −z

2) at energy ω

2 increases with increase of

temperature. Hence from peak positions at ω� .

2(z� +z

2) and ω

2 . 2(z

� −z

2) the magnitudes of the

individual gap values at different temperatures

can be calculated by using the formula developed

by the present model.

For the electron-phonon(EP) coupling

constant s = 0.�55 to 0.20, we observe two

ultrasonic absorption peaks corresponding to

the high energy peak at energy 2(z� +z

2) and low

energy peak at energy 2(z� −z

2). The EP coupling

is comparable to the value observed for the

CDW superconductors. Similar suppression of

spectral height with increase of temperature is

observed in NCCO and LSCO system indicating

the phase change in the system. In conclusion we

emphasize that our model calculation will guide

the experimentalist to calculate the individual

order parameters of the mutually competing

interactions like CDW and SDW at different

temperatures, impurity concentrations and

external magnetic fields.

references

[�] G. Cannelli, R. Cantelli and F. Cordero, Int. J. Mod. Phys. B5 (�9��) ��57.

[2] G.C. Rout, B. N. Panda and S. N. Behera, Solid Stat Comm. �05 (�99�) �7.

[3] K. C. Bishoyi, G.C. Rout and S. N. Behera, Indian J. Phys 76A(�) (2002) �7.

[�] G.C. Rout, B. N. Panda and S. N. Behera, Solid State Comm. �06 (�99�) �69.

[5] G.C. Rout, K. C. Bishoyi and S. N. Behera, Physica c �20 (2005) 37.

[6] G. Shirane et al., Phys. Rev. Lett. 59 (�9�7) �6�3.[7] K. B. Lyons et al., Phys. Rev. B 37 (�9�7) 2353.[�] S. K. Panda and G.C. Rout, Physica C. �69 (2009) 702.[9] G. C. Rout and S. K. Panda, Physica C. (20�0)

(Communicated)



CONDUCTING POLYMERS BASED SENSORS : AN ARTIFICIAL NEURAL NETWORK APPROACH

B.K. Parija, P.K.Sahoo, B. Prusty, A.R. Routray and M.C. Adhikary

P.G. Dept. of Applied Physics & Ballistics, F.M. University, Balasore

Corresponding author : [email protected]

ABSTRACT

A brief overview of research and development in the field of conducting polymers

based sensors with Artificial Neural Network is presented. The conducting polymers

with electrical and optical properties can be used in sensor devices either participate in

sensing mechanism or immobilize the component responsible for sensing the analyte.

In this aspect, the electronic tongue using Artificial Neural Network (ANN) approach

for taste classification based on the biological sensory systems , has been developed

rapidly during the last few years. The electronic tongue system (ETS) uses several sensors

fabricated from nanostrutured thin films of different polymers that are deposited on

the top of an interdigitated micro electrode. Introduction of new series of integrated

artificial Intelligence/conducting polymer based sensor gives analytical responses,

which look irreversible and non producible, are combined by an artificial intelligence

trained computer by which reproducible output, based on the created model and pattern

by the computerized system, can be predicted . Pattern recognition techniques are

described with Artificial Neural Network.So these electro-active conducting polymers

cover a broad spectrum of applications from solid-state technology to biotechnology

and sensor technology.

Key Words : Artificial neural network (ANN), Electronic tongue, Pattern recognition, Conducting Polymers,

ASMOD, Processing elements, Neuro fuzzy.

1.introduction:

A new class of polymers known as intrinsically

conducting polymers (CPs) or electroactive

conjugated polymers exibit interesting electrical

and optical properties , which are found only

in inorganic systems. Electrically conducting

polymers differ from aa the familiar inorganic

semiconductors ( silicon and germanium ) in two

important features that polymers are molecular in

nature and lack long-range order [�]. Conducting

Polymers contain π-electron backbone which

is responsible for their unusual electronic

properties such as electrical conductivity, low

energy optical transitions, low ionization potential

and high electron affinity and are also used

to enhance speed, sensitivity and versatility of

sensors. Properties of CPs depend strongly on

doping level, ion size of dopant, protonation level

and water content. CPs finding ever-increasing

use in diagnostic medical reagents and with a

distinguishable chemical memory, are prominent

new materials for fabrication of industrial sensors.

2. sensors Based on transduction :

Sensors may be classified depending on the

mode of transduction into the categories like

potentiometric sensors, amperometric sensors,

piezoelectric sensors, calorimetric / thermal

sensors and optical sensors.

i) Potentiometric sensors :

The potentiometric sensors may be either symmetric

or asymmetric. In symmetric potentiometric sensors

, the selective membrane is symmetrically bathed

by two electrolyte solutions and an external sample

solution. In asymmetric potentiometric sensors,

there is no internal filling solution. Hence , the sensor

membrane is only in contact with one aqueous

phase i.e. the sample , while the internal contact is

with a solid-state ionic or electronic conductor. In

potentiometric sensors, cell potential is monitored in

zero current condition ( equilibrium ) [2]. Example

includes a sensor for glucose by glucose oxidase

with the activity of fluoride ions through the action

of a second catalytic reaction on an organofluorine

compound.

ii) Amperometric Sensors :

In amperometric sensors, signal is propotional

to the concentration of analyte species. Suitable

target species are electroactive species that are

capable of being oxidized or reduced, with the

oxidation or reduction potential being zero. In a

biosensor , concentration of an enzyme substrate

is measured indirectly through the consumption

of oxygen by oxidase enzyme catalyzed reactions

or by the generation of the hydrogen peroxide

(H2O

2). Oxygen and H

2O

2 being the co-substrates

and the product of several enzyme reactions

are detected for amperometric estimation.

The electrochemical biosensors are based on

mediated or unmediated electrochemistry for

electron transfer [3].

iii) Piezoelectric Sensors :

In piezoelectric sensor , an acoustic wave is

propagated by an externally applied alternating

current between two electrodes or interdigited

electrode fingers deposited on a piezoelectric

substrate such as quartz. The subclasses of

piezoelectric transducers are based on the way of

acoustic wave propagated between the electrodes.

Most applications of these devices have been

found for gas phase monitoring , where hydrogen

sulphide,carbon dioxide, oxygen, nitrogen dioxide,

molecular hydrogen, mercury, toluene and actone

sensors have been fabricated[2].

iv) Calorimetric/Thermal Sensors :

Thermistors, whose resistance changes markedly

with temperature, are often employed as cheap,

sensitive temperature sensors. The most commenly

used approach in the thermal enzyme probes[�]

is related to the enzyme directly attached to the

thermistor. It is observed that the heat evolved in

Contributed Paper



CONDUCTING POLYMERS BASED SENSORS : AN ARTIFICIAL NEURAL NETWORK APPROACH

B.K. Parija, P.K.Sahoo, B. Prusty, A.R. Routray and M.C. Adhikary

P.G. Dept. of Applied Physics & Ballistics, F.M. University, Balasore

Corresponding author : [email protected]

ABSTRACT

A brief overview of research and development in the field of conducting polymers

based sensors with Artificial Neural Network is presented. The conducting polymers

with electrical and optical properties can be used in sensor devices either participate in

sensing mechanism or immobilize the component responsible for sensing the analyte.

In this aspect, the electronic tongue using Artificial Neural Network (ANN) approach

for taste classification based on the biological sensory systems , has been developed

rapidly during the last few years. The electronic tongue system (ETS) uses several sensors

fabricated from nanostrutured thin films of different polymers that are deposited on

the top of an interdigitated micro electrode. Introduction of new series of integrated

artificial Intelligence/conducting polymer based sensor gives analytical responses,

which look irreversible and non producible, are combined by an artificial intelligence

trained computer by which reproducible output, based on the created model and pattern

by the computerized system, can be predicted . Pattern recognition techniques are

described with Artificial Neural Network.So these electro-active conducting polymers

cover a broad spectrum of applications from solid-state technology to biotechnology

and sensor technology.

Key Words : Artificial neural network (ANN), Electronic tongue, Pattern recognition, Conducting Polymers,

ASMOD, Processing elements, Neuro fuzzy.

1.introduction:

A new class of polymers known as intrinsically

conducting polymers (CPs) or electroactive

conjugated polymers exibit interesting electrical

and optical properties , which are found only

in inorganic systems. Electrically conducting

polymers differ from aa the familiar inorganic

semiconductors ( silicon and germanium ) in two

important features that polymers are molecular in

nature and lack long-range order [�]. Conducting

Polymers contain π-electron backbone which

is responsible for their unusual electronic

properties such as electrical conductivity, low

energy optical transitions, low ionization potential

and high electron affinity and are also used

to enhance speed, sensitivity and versatility of

sensors. Properties of CPs depend strongly on

doping level, ion size of dopant, protonation level

and water content. CPs finding ever-increasing

use in diagnostic medical reagents and with a

distinguishable chemical memory, are prominent

new materials for fabrication of industrial sensors.

2. sensors Based on transduction :

Sensors may be classified depending on the

mode of transduction into the categories like

potentiometric sensors, amperometric sensors,

piezoelectric sensors, calorimetric / thermal

sensors and optical sensors.

i) Potentiometric sensors :

The potentiometric sensors may be either symmetric

or asymmetric. In symmetric potentiometric sensors

, the selective membrane is symmetrically bathed

by two electrolyte solutions and an external sample

solution. In asymmetric potentiometric sensors,

there is no internal filling solution. Hence , the sensor

membrane is only in contact with one aqueous

phase i.e. the sample , while the internal contact is

with a solid-state ionic or electronic conductor. In

potentiometric sensors, cell potential is monitored in

zero current condition ( equilibrium ) [2]. Example

includes a sensor for glucose by glucose oxidase

with the activity of fluoride ions through the action

of a second catalytic reaction on an organofluorine

compound.

ii) Amperometric Sensors :

In amperometric sensors, signal is propotional

to the concentration of analyte species. Suitable

target species are electroactive species that are

capable of being oxidized or reduced, with the

oxidation or reduction potential being zero. In a

biosensor , concentration of an enzyme substrate

is measured indirectly through the consumption

of oxygen by oxidase enzyme catalyzed reactions

or by the generation of the hydrogen peroxide

(H2O

2). Oxygen and H

2O

2 being the co-substrates

and the product of several enzyme reactions

are detected for amperometric estimation.

The electrochemical biosensors are based on

mediated or unmediated electrochemistry for

electron transfer [3].

iii) Piezoelectric Sensors :

In piezoelectric sensor , an acoustic wave is

propagated by an externally applied alternating

current between two electrodes or interdigited

electrode fingers deposited on a piezoelectric

substrate such as quartz. The subclasses of

piezoelectric transducers are based on the way of

acoustic wave propagated between the electrodes.

Most applications of these devices have been

found for gas phase monitoring , where hydrogen

sulphide,carbon dioxide, oxygen, nitrogen dioxide,

molecular hydrogen, mercury, toluene and actone

sensors have been fabricated[2].

iv) Calorimetric/Thermal Sensors :

Thermistors, whose resistance changes markedly

with temperature, are often employed as cheap,

sensitive temperature sensors. The most commenly

used approach in the thermal enzyme probes[�]

is related to the enzyme directly attached to the

thermistor. It is observed that the heat evolved in

Contributed Paper



the enzymatic reactions is lost to the suurounding

solution without being detected by thermistor

resulting in the decrease in sensitivity of the

biosensor.

v) Optical Sensors :

Optical sensors are based on the measurements

of light absorbed or emitted as a consequence of

a biochemical reaction. Light waves are guided by

means of optical fibers to suitable detectors. Such

sensors can be used for measurement of pH, O2,

CO2 etc.

3.sensors Based on applications :

Sensors may be classified depending on the mode

of applications into the categories like Chemical

sensors- gas sensors, pH sensors, ion—selective

sensors, alcohol sensors, humidity sensors and

Biosensors.

i) Chemical Sensors :

Chemical sensors convert a chemical state into

an electric signal. In such sensors, a sensitive

layer is in chemical contact wuth the analyte. A

change in the chemistry of the sensitive layer

(a reaction) is produced after the exposure to

analyte. The sensitive layer is on a platform that

allow stransconduction of the change to electric

signals.Every chemical sensor is divided into

two domains, the physical transuducer and the

chemical interface.And conducting polymers

used for gas sensors with acid,base or oxidizing

characteristics shows good results. Sensors are

designed by the electrochemical deposition

of appropriate polymer across a gap of �2µm

between two gold microband electrodes. Most

of the widely used CPs are polythiophene and

its derivatives , polypyrrole polyaniline and

composites of these polymers[5].

ii) Biosensors :

Biosensor is an analytical device incorporating a

biological or biological derived material, either

inyimately associated or integrated within a

physico-chemical transducer. The change in

electronic conductivity of conducting polymers in

response to change in pH has been made use of

in fabricating sensors for biomolecules.Here the

CPs are formed by a combination of donor and

acceptor systems.

4. artificial intelligence methods in conducting

Polymer :

Conducting polymer based sensors which

possess an array of attributes rarely found in

other materials. Appropriate manipulation of

the material composition can be used to induce

specific molecular (stimuli) recognition properties,

and electronic properties of the materials are such

that electrical information can be generated and

processed[6].Moreover, the electrochemically

controlled chemical nature of the polymers is

such that response actuation is readily achieved.

Although conducting polymer based sensors

have been used in variety of applications, there

have been very few cases that they have been

utilized in a commercial products . This is due

to the dynamic nature of these materials which

causes reproducibility problems . Considering

the passive approaches used to control the

dynamic intelligence of these smart materials,

there has not been much success in keeping their

behaviour under control. So the adaptive and

dynamic artificial intelligence methods can be

introduced to challenge and control the output

behaviour of an intelligent conducting polymer

based sensory system. Therefore, an approach is

taken by an intelligent process control system

in which the physical and chemical properties

of such smart materials can be dynamically

controlled. And for this the application of

artificial intelligence, neuro-fuzzy and neural

network [7], in conducting polymer based

sensors are adopted.

i) Artificial Neural Network :

Artificial neural networks (ANN) are massively

parallel inter connected networks of simple

organizations (processing elements) which

are intended to interact with the objects of

real world in the same way as the biological

neural systems do [��. These parallel distributed

models are potentially capable of performing

nonlinear modelling and adaptation without

any assumptions about the model . In very broad

terms, the ANN may be defined as an attempt to

capture the human brains capabilities for solving

complex problems. The term “artificial neural

network” is used to describe a number of different

models intended to imitate some functions of

human brains.

In a neural network, input patterns

(data signals) are connected to the processing

elements of the input layer and the outputs of

these elements are connected to the inputs

of the elements in the next layer .There is one

processing element ( PE ) for each input in

the input layer and one PE for each output in

the output layer . In addition, a few arbitrary

hidden layers inty also be inserted between the

input and output layers . The resulting network

configuration is shown in Figure- �, and is known

as the multilayer perceptron (MLP)[�]. The use of

more hidden layers permits better handling of

more complex nonlinear functions.

Figure-� : Network cofiguration of ANN

ii)Adaptive Spline Modelling of Observation

Data (ASMOD) :

The ASMOD algorithm is an off-line iterative

modelling approach which has the potential of

real-time learning, dealing with time-varying

systems . It has been successfully implemented

in a wide range of applications . ASMOD uses B-

splines to represent general nonlinear and coupled

dependencies in multivariable observation

data. B-Splines are commonly used in computer

graphics and CAD systems for representing

three dimensional curves and surfaces with

high accuracy. In the ASMOD algorithm the

output variable is modelled as a sum of several

low dimensional sub models, where each

submodel only depends on a small subset of the

input variables. The decomposition of the high

dimensional input space into low dimensional

additive subspecies makes the model transparent

to the user, and at Inputs Sigmoid Hard limit. The

ASMOD modelling scheme can be mapped into a

three layered feed-forward neural network, using



the enzymatic reactions is lost to the suurounding

solution without being detected by thermistor

resulting in the decrease in sensitivity of the

biosensor.

v) Optical Sensors :

Optical sensors are based on the measurements

of light absorbed or emitted as a consequence of

a biochemical reaction. Light waves are guided by

means of optical fibers to suitable detectors. Such

sensors can be used for measurement of pH, O2,

CO2 etc.

3.sensors Based on applications :

Sensors may be classified depending on the mode

of applications into the categories like Chemical

sensors- gas sensors, pH sensors, ion—selective

sensors, alcohol sensors, humidity sensors and

Biosensors.

i) Chemical Sensors :

Chemical sensors convert a chemical state into

an electric signal. In such sensors, a sensitive

layer is in chemical contact wuth the analyte. A

change in the chemistry of the sensitive layer

(a reaction) is produced after the exposure to

analyte. The sensitive layer is on a platform that

allow stransconduction of the change to electric

signals.Every chemical sensor is divided into

two domains, the physical transuducer and the

chemical interface.And conducting polymers

used for gas sensors with acid,base or oxidizing

characteristics shows good results. Sensors are

designed by the electrochemical deposition

of appropriate polymer across a gap of �2µm

between two gold microband electrodes. Most

of the widely used CPs are polythiophene and

its derivatives , polypyrrole polyaniline and

composites of these polymers[5].

ii) Biosensors :

Biosensor is an analytical device incorporating a

biological or biological derived material, either

inyimately associated or integrated within a

physico-chemical transducer. The change in

electronic conductivity of conducting polymers in

response to change in pH has been made use of

in fabricating sensors for biomolecules.Here the

CPs are formed by a combination of donor and

acceptor systems.

4. artificial intelligence methods in conducting

Polymer :

Conducting polymer based sensors which

possess an array of attributes rarely found in

other materials. Appropriate manipulation of

the material composition can be used to induce

specific molecular (stimuli) recognition properties,

and electronic properties of the materials are such

that electrical information can be generated and

processed[6].Moreover, the electrochemically

controlled chemical nature of the polymers is

such that response actuation is readily achieved.

Although conducting polymer based sensors

have been used in variety of applications, there

have been very few cases that they have been

utilized in a commercial products . This is due

to the dynamic nature of these materials which

causes reproducibility problems . Considering

the passive approaches used to control the

dynamic intelligence of these smart materials,

there has not been much success in keeping their

behaviour under control. So the adaptive and

dynamic artificial intelligence methods can be

introduced to challenge and control the output

behaviour of an intelligent conducting polymer

based sensory system. Therefore, an approach is

taken by an intelligent process control system

in which the physical and chemical properties

of such smart materials can be dynamically

controlled. And for this the application of

artificial intelligence, neuro-fuzzy and neural

network [7], in conducting polymer based

sensors are adopted.

i) Artificial Neural Network :

Artificial neural networks (ANN) are massively

parallel inter connected networks of simple

organizations (processing elements) which

are intended to interact with the objects of

real world in the same way as the biological

neural systems do [��. These parallel distributed

models are potentially capable of performing

nonlinear modelling and adaptation without

any assumptions about the model . In very broad

terms, the ANN may be defined as an attempt to

capture the human brains capabilities for solving

complex problems. The term “artificial neural

network” is used to describe a number of different

models intended to imitate some functions of

human brains.

In a neural network, input patterns

(data signals) are connected to the processing

elements of the input layer and the outputs of

these elements are connected to the inputs

of the elements in the next layer .There is one

processing element ( PE ) for each input in

the input layer and one PE for each output in

the output layer . In addition, a few arbitrary

hidden layers inty also be inserted between the

input and output layers . The resulting network

configuration is shown in Figure- �, and is known

as the multilayer perceptron (MLP)[�]. The use of

more hidden layers permits better handling of

more complex nonlinear functions.

Figure-� : Network cofiguration of ANN

ii)Adaptive Spline Modelling of Observation

Data (ASMOD) :

The ASMOD algorithm is an off-line iterative

modelling approach which has the potential of

real-time learning, dealing with time-varying

systems . It has been successfully implemented

in a wide range of applications . ASMOD uses B-

splines to represent general nonlinear and coupled

dependencies in multivariable observation

data. B-Splines are commonly used in computer

graphics and CAD systems for representing

three dimensional curves and surfaces with

high accuracy. In the ASMOD algorithm the

output variable is modelled as a sum of several

low dimensional sub models, where each

submodel only depends on a small subset of the

input variables. The decomposition of the high

dimensional input space into low dimensional

additive subspecies makes the model transparent

to the user, and at Inputs Sigmoid Hard limit. The

ASMOD modelling scheme can be mapped into a

three layered feed-forward neural network, using



B-spline basis functions as the nonlinearities of

the hidden layer, and a linear transfer function for

the output layer.

5. conclusion :

The majority of sensor devices utilize many

polymers with definite roles, either in the sensing

mechanism or through immobilizing the species

responsible for sensing of the analyte components.

This has become possible only because polymers

may be tailored for particular properties, are easily

processed.Application of artificial intelligence

methods (neural network and neuro-fuzzy

methods) to enhance the performance of the

conducting polymer based ion detectors has

been addressed. This new computer based data

processing has been developed for pattern

recognition applications. It has been found

that the patterns and models created by neural

network and ASMOD algorithm can predict the

type and the concentration of ions existing in the

operational environment with acceptable level

of accuracy. A combination of these methods is

recommended to achieve an optimum intelligent

computer based system to address a new and

novel dynamic process control and online

prediction.

references :

[�] Duke C B and Schem L B : Organic solids : is energy-based theory enough ? Phys Today, 33, �9�0, �2-��.

[2] Janata J Ed, Principles Chemical Sensors, Plenum Press, New York, �9��, �5��-�592.

[3] Chaubey A and Malhotra B D , Mediated biosensors review, Biosensors and Bioelectronics,�7,2002 , ��-�56.

[�] Mosbach K and Danielsson B, Thermal bioanalyzers in flow stream enzyme thermister devices, Anal Chem., 5�, �9�6,2979-29�3.

[5] Barlett P N and Long-Chung S K , Conducting polymer gas sensors part III : results for four different polymers, Sensors & Actuators B,�0,�997, 99-�03.

[6] Talde A., Sadk O. and Wallace G.G., J. of Mat Sys., �, �993, �23.

[7] Kahane T., Self Organization and Associative Memory, Springer, �9�9.

[�] A.R. Routray & M.C.Adhikary : Image Compression based Wavelet and Quantization with Optimal Huffman Code, International Journal of Computer Applications, August 20�0, Vol 5 ,No 2 , P-6-9.

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