by Tom Matthams

Department of Materials Science and Metallurgy,University of Cambridge,Pembroke StreetCambridge CB2 3QZ, UKEmail: tjm16@cam.ac.uk

Located in the heart of Cambridge, UK, the

University’s Department of Materials Science and

Metallurgy occupies buildings that range from the

original home of the Cavendish Laboratory, built in

1873, to a new seminar room completed in 2000.

The site is the scene of some of the most significant

advances in science, including the discovery of the

electron in 1897 and the elucidation of the structure

of DNA in 1953. Within these historic, and also more

modern buildings, the department’s laboratories are

well equipped to characterize and fabricate all types

of materials.

The department has a large and vigorous research

school, with about 100 research fellows,

postdoctoral, and visiting scientists, as well as more

than 120 research students studying for PhD degrees.

The growth in research activities over the past 20

years has been almost exponential, with a current

research income of more than $6 million per year and

a doubling time of about seven years. Although our

research has always been closely linked to industrial

needs and supported in large part by industry as well

as government, recent trends have seen the

development of larger-scale working relationships

with major research sponsors such as Rolls-Royce,

Regenesys Technologies, and Pfizer. Similarly, the

wide range of international contacts, which bring

visiting researchers to Cambridge from all over the

world, has been extended through formal

collaboration agreements with institutions in

Switzerland, Singapore, and, most recently, the US via

the Cambridge-MIT Institute (CMI).

The department is one of the leading materials science

departments in the world. It was awarded the top rating in

the most recent UK Research Assessment Exercise (December

2001), which assesses the quality of research in UK

universities and colleges.

The Department of Materials Science and Metallurgy plays

a central and major role in the research and teaching of

materials science. With a large number of academic staff and

researchers, the department is very diverse in the areas of

Building onhistoric success

ISSN:1369 7021 © Elsevier Science Ltd 2002December 200248

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materials science under investigation. Research at Cambridge

is nominally divided into five broad areas (Fig. 1). Two

additional research areas, electron microscopy and materials

modeling, impinge upon all areas of research throughout the

department and hence are shown as all encompassing.

The department is home to graduate students from all

over the world, mostly studying for PhD degrees. About 30

new graduate students arrive each year, many of whom join

with backgrounds in physics, chemistry, or engineering. PhD

student numbers have more than doubled since 1985 (in

1985 there were 62 students, now there are almost 130).

Cambridge has the largest number of research students of

any materials department in the UK.

The largest growth area in the department over the last

few years has been in the area of biomaterials. A

departmental strategic plan, devised at the time of the 1996

Research Assessment Exercise, identified biomedical materials

as an area of materials science that Cambridge was keen to

explore. In 2000, with help from the Newton Trust, a new

chair was created in the department and Bill Bonfield was

brought to the department from the Interdisciplinary

Research Centre in Biomedical Materials to spearhead the

new group. Working closely with Bonfield are Serena Best and

Ruth Cameron, from Cambridge Materials Science, and Neil

Rushton, from the Orthopedic Research Unit at Addenbrookes

Hospital, together forming the Cambridge Centre for Medical

Materials (CCMM). CCMM has grown rapidly to become one

of the department’s largest research areas.

Further growth in this area is imminent with the

announcement of the Pfizer Institute for Pharmaceutical

Materials Science in February 2002. The Institute is a research

collaboration between the University of Cambridge, the

Cambridge Crystallographic Data Centre (CCDC), and Pfizer

Ltd., and will be directed by Bonfield. Under the terms of the

five year agreement, Pfizer will provide support for up to 21

research staff and students. The aim of the Institute is to

provide a focus for research into all aspects of the structure,

manufacture, and behavior of solid dosage forms, such as

tablets, at all relevant scales of operation and use. The

research will range in size-scales, modeling the processes of

molecular crystallization through to achieving better powder

compaction, tableting, diffusion, and release. As Bonfield

explains, “Pfizer have provided an exciting opportunity for us

to perform some world-class research in establishing a

distinctive approach to the formulation and delivery of

pharmaceutical materials. The collaboration between the

Department of Materials Science and Metallurgy, Department

of Chemistry, the CCDC, and the direct link with scientists at

Pfizer will create a major interdisciplinary team that will

allow for radical research and new insights.”

Materials chemistry is another major group within the

Cambridge department. Led by the current head of

department Derek Fray, research includes electrochemical

reduction of molten salts as a method of producing metallic

phases (of which Ti production has received most publicity),

studies into ion transport properties of materials – for

example, membranes that are selectively conductive –

used in liquid state redox fuel cells for energy storage

technology, and chemical sensors that can rapidly detect

gases such as NOx.

The Fray, Farthing, and Chen (FFC) process is a novel

method where an oxide is made at the cathode in a bath of

molten CaCl2. The favored cathodic reaction is the ionization

of O2 and not the deposition of Ca. The net result is that the

O2 ionizes and dissolves in the salt, leaving pure metal

behind. This patented process has been used to produce Ti,

Zr, Cr, and Nb amongst others. The process is flexible such

that alloys or intermetallic compounds can be produced by

preparing a mixture of oxides at the cathode. The method

offers the possibility of reducing the cost of production of

many metals and their alloys, and is currently undergoing

pilot plant trials.

December 2002 49

Fig. 1 Research themes within Cambridge’s materials science department.

In collaboration with Regenesys Technologies Ltd.,

researchers in Cambridge are studying materials for

regenerative fuel cell technologies. The membrane forms a

key part of the electrochemical cell, separating the

electrochemical salt solutions (Fig. 2). At times of oversupply,

excess electricity can be stored by ‘charging up’ one of the

electrolytes. When this energy is required, the electrolyte can

be discharged through the electrochemical cell to provide

power to the national grid. The technology is highly efficient

and flexible enough to provide energy storage of up to

500 MW for a few seconds or as long as a few hours.

In the field of device materials, Jan Evetts leads a team

studying magnetic, ferroelectric, and superconducting

materials. Some of Evetts’ recent work involves studying the

variation of critical current densities at grain boundaries. A

good understanding of the variation of critical current density

with angle of applied magnetic field is vital for the

development of long lengths of superconducting tape.

Detailed measurements have been performed on samples of

YBa2Cu3O7 with 4° grain boundaries, and variations of up to

half an order of magnitude have been found in critical current

density as the applied magnetic field is rotated in plane.

MgB2 is a relatively new superconducting material,

discovered in early 2001. It is capable of superconducting at

temperatures of up to 40 K, which is achievable with

mechanical cryocoolers. This gives the possibility of making

superconducting devices that can be operated at a relatively

low cost – as there is no requirement for liquid helium

cooling. The Cambridge group are now using a focused ion

beam system to produce the best MgB2 devices in the world.

Fig. 3 shows a simple Josephson Junction made in Cambridge

from MgB2.

Magnetic sensors form another important part of the

group’s work. A recent development stemming from a UK

Department of Trade and Industry LINK Sensors program

involving Telcon Ltd., has produced a remote magnetic field

sensor that is capable of high sensitivity at very high

currents. The device is based on a magnetic Wheatstone

bridge design and incorporates micropatterned spin valve

structures. The resulting device is easy to manufacture at

relatively low cost and should find applications in a wide

range of fields where accurate current monitoring and control

of large currents is required.

The high resolution electron microscopy group has a well

deserved reputation as one of the best in the world. The

group operates the most advanced microscopes in the

country, including the 300 kV Phillips CM300 FEG

transmission electron microscope (TEM) and the 200 kV FEI

Tecnai F20. These microscopes are state-of-the-art machines

used for high resolution and analytical TEM and scanning TEM

(STEM) work. The field emission sources that these

microscopes use mean they are ideal for applications

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December 200250

Fig. 2 A single regenerative fuel cell, showing electrolyte and electrical connections. (Image courtesy of Regenesys Technology Ltd.)

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requiring high coherency, high brightness at high

magnification, or small focused probes. These and other

microscopes are being used to investigate the structure and

chemistry of a range of materials at the sub-nanometer level.

The group is studying contrast in high resolution microscope

images and attempting to correlate the observed intensities

with those obtained from modern theoretical calculations.

There is still not perfect agreement, but the group is getting

closer all the time.

Electron holography is being used to characterize the

magnetic fields in a range of nanostructured magnetic

materials. This technique can be used to determine magnetic

field distribution on the scale of a few angstroms, which is by

far the most sensitive technique available today. Holography

can also be used to investigate the electrostatic fields in a

specimen, and by using a novel sample-biasing specimen

holder it has been possible to visualize electric fields on the

nanometer scale in a working metal-semiconductor field-

effect-transistor (MESFET) device.

Electron tomography is also being used to characterize the

microstructure and chemistry of materials in three-

dimensions at a resolution of a few nanometers. Specimens

with dimensions of the order of 100 nm x 100 nm x 100 nm

can be studied using a specialized specimen holder that

allows very high angles of tilt within the microscope (up to

80°). Large numbers of images are taken and then assimilated

by a computer to generate the three-dimensional structure.

Examples of materials, which have been studied using this

technique, include small crystallites and catalyst particles

within zeolite matrices. The reconstruction of the crystallites

is of high enough quality that, in combination with possible

crystal structures, it is possible to fully index the resolved

facets of each crystallite, as shown in Fig. 4.

Overlapping with the device materials and high resolution

electron microscopy groups is a new group investigating the

processing and properties of GaN, led by Colin Humphreys.

“GaN is probably the most important semiconductor

material since silicon,” claims Humphreys. GaN emits

brilliant light, as well as being the key material for next

generation high-frequency, high-power transistors capable

of operating at high temperatures. It offers the possibility

of producing light-emitting diodes (LEDs) of almost any

color in the visible spectrum. With a suitable phosphor

coating, blue LEDs can produce white light. This is set to

revolutionize industrial and domestic lighting systems by

providing low energy, long lasting (up to 100 000 hours),

low cost lightbulbs.

At the heart of the GaN Centre is a new state-of-the-art

six by two-inch wafer metalorganic chemical vapor

deposition (MOCVD) growth system, which was established

in collaboration with Thomas Swan Scientific Equipment Ltd

and is worth in the region of $770 000. The growth

December 2002 51

Fig. 3 Josephson Junctions fabricated in MgB2 superconductor. (Image courtesy of Gavin Burnell.)

equipment is now fully operational and producing world-class

GaN-based materials and devices.

As computers get more powerful and experiments get

more expensive to perform, materials modeling is becoming

an important element in industrial process development. This

is also reflected in the activities of the department – it is now

a major element in both teaching and research.

The Master of Philosophy (a one year postgraduate course)

in materials modeling ran for the first time in 2000-2001.

This is an exciting new interdisciplinary course funded by the

UK Engineering and Physical Science Research Council

EPSRC). It is a collaboration between the Departments of

Materials Science and Metallurgy, Engineering, and Physics,

with contributions from manufacturing industries. The course,

led by Harry Bhadeshia and Zoe Barber, has taken students

from diverse scientific backgrounds, ranging from biologists

to mathematicians, and given them a solid introduction to

materials science and the techniques used to model

properties and processes. The main aims of the course are to

provide a broad training in materials and process modeling,

and to instill confidence in a variety of techniques covering

the engineering scale down to atomic dimensions. The course

has proved very successful in its first two years and the

department has just welcomed the class of 2002.

Industrial partnershipsWith core government and research council funding

becoming more and more competitive, the department is

evermore reliant on industrial funding to continue its

research. Over the last decade, the department has nurtured

a significant number of long-term partnerships with major

companies in addition to the numerous smaller research

projects that are successfully carried out by the staff and

students of the department. Back in 1994, Rolls-Royce set up

the University Technology Centre (UTC) within the

department to study Nil-based superalloys for future

aeroengine power plants. The UTC was set up on a five year

rolling contract, initially valued at over $2.3 million, which

provided long term funding for a number of senior research

staff, as well as research studentships. This was a vast

improvement on the usual three-year fixed-term contracts,

which did not offer senior researchers any guarantee of

stability. Under the directorship of Humphreys, this center

has blossomed and now forms a core part of the Rolls-Royce

research strategy.

Following the Rolls-Royce UTC, the Defence Evaluation

and Research Agency (DERA) supported Gordon Laboratory

became the second embedded unit to be formed within the

department. Following the split of DERA into QinetiQ and the

Defence Science and Technology Laboratory (DSTL), the

laboratory is now supported by QinetiQ. Under the leadership

of Bill Clyne, the laboratory’s work centers on the properties

and processing of advanced composite materials. The

laboratory has an emphasis on fiber-reinforced polymeric

materials, but metallic- and ceramic-based composites are

also under investigation. The laboratory was opened in June

1999 by Sir John Chisholm, the then chief executive of DERA

and Theodora Gordon, widow of James Gordon after whom

the laboratory is named. Gordon’s books on the subject of

materials science and engineering have been an inspiration to

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December 200252

Fig. 4 High resolution electron tomography allows the indexing of individual crystallites. (Reproduced with permission from: Buseck et al., PNAS (2001) 9988 (24), 13490-13495 © (2001)National Academy of Sciences, USA.)

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more than a generation of students and it is hoped that some

of his enthusiasm for the subject will rub off on the current

cohort of undergraduate and postgraduate students.

Innogy (now Regenesys Technologies) funded the third

UTC in 2001. The New Materials for Innovative

Electrochemistry Center is led by Fray and George Chen, with

the focus of its research efforts on fuel cells (Fig. 2).

Building on the success of these partnerships, in addition

to the collaborations with Thomas Swan and Pfizer described

earlier, the department is always keen to nurture new long-

term relationships with industrial bodies.

The Cambridge ConnectionCambridge, UK, and Cambridge, Massachusetts, USA, are both

homes to world-class universities. The materials science

department in Cambridge, UK, has for many years

collaborated with researchers at the Massachusetts Institute

of Technology (MIT), and this collaboration has received a

welcome financial boost in recent years with the

establishment of The Cambridge-MIT Institute (CMI). Alan

Windle, former head of department in Cambridge, UK, is

executive director of the CMI and is keen to see some of the

entrepreneurship for which MIT is famed rub off on his

Cambridge colleagues through these joint projects. Funded

primarily by the DTI with a grant of over $100 million,

awarded in June 2000, and with the aim of raising a further

$25 million over five years from the UK private sector, CMI

has set up a number of exciting research projects in the UK

department. Three major CMI-funded projects have been set

up within the department, including investigations into the

properties of carbon nanotubes (under the leadership of

Fray), development of ultralight stainless steel sheet (Clyne),

and the formation of an interdisciplinary research cluster into

biomaterials and tissue engineering (Bonfield). The latter is a

major project involving over a dozen senior staff on both

sides of the Atlantic and has received a grant of $3 million

over three years from the CMI.

Attracting more studentsAll materials science departments across the UK are

struggling to maintain student numbers. A large number of

materials departments have either closed their undergraduate

courses or been merged with, typically, engineering, resulting

in the study of materials becoming merely a minor option

within a general engineering course. This is obviously a

serious issue for everyone involved with materials science, as

fewer materials graduates will lead to a lack of capability

within UK industry in coming years. Physics and chemistry

are well understood as subjects by the general public, but

materials science is less well known.

In addition to the work being done by the Institute of

Materials, Minerals and Mining to promote materials science

to a wider audience, there are a number of initiatives

operating within the department to increase awareness of

materials science, particularly among the younger generation.

Rob Wallach has coordinated a program for primary school

children called SeeK (Science and Engineering Experiments for

Kids). This program puts graduate students from the

department into local primary schools to help the children

perform exciting scientific experiments that are carefully

designed to illustrate central principles and, more

importantly, get the children interested in science.

Undergraduates are often the most willing users of new

technology, and computer-based learning is rapidly becoming

an important cog in the process of disseminating knowledge

to students. A $500 000 Higher Education Funding Council

for England (HEFCE) funded project – Dissemination of

Information Technology for the Promotion of Materials

Science (DoITPoMS) – has been running in the department for

the past three years. Early resources that have emanated

from the program include a fully searchable micrograph

library covering a vast range of materials, and a series of

web-based teaching and learning packages designed to cover

a series of specific topics studied at undergraduate level.

There is collaboration with five other UK materials

departments via the project, and strong links with the UK

Centre for Materials Education in Liverpool.

The futureThe department has no intention of sitting back and basking

in the successes of its past. The biggest inhibitor of continued

growth is not lack of ideas or research funding, but physical

space in which to carry out the research. A move to a new

dedicated facility within the University’s West Cambridge

Site has reached the outline design stage and could take

place within the next few years.

Materials science in Cambridge is in a healthy position to

build on the successes of the past. The people, ideas, and

resources are all in place to produce the scientists and

entrepreneurs of the future. MT

December 2002 53