1. Semi Conductor - Ijsst - Effect of Ni-doping on Structural and - Raminder Preet Pal Singh

8/20/2019 1. Semi Conductor - Ijsst - Effect of Ni-doping on Structural and - Raminder Preet Pal Singh

http://slidepdf.com/reader/full/1-semi-conductor-ijsst-effect-of-ni-doping-on-structural-and-raminder 1/10

www.tjprc.org [email protected]

EFFECT OF NI-DOPING ON STRUCTURAL AND MAGNETIC PROPERTIES

OF ZnO NANOPARTICLESRAMINDER PREET PAL SINGH 1, I. S. HUDIARA2,

SUDHAKAR PANDAY3 & PUSHPENDRA KUMAR4 1,3Department of Electronics & Communication Engineering, Desh Bhagat University,

Mandi Gobindgarh, Punjab, India2Chitkara University (Punjab Campus), Chandigarh, India

4Department of Chemistry, Arni University, Kangra, Himachal Pradesh, India

ABSTRACT

In the present study, Zn1-xNixO (x=0.01, 0.03, 0.05 and 0.07) diluted magnetic semiconductor (DMS)

nanoparticles have been synthesized using modified sol-gel method. The structural and magnetic properties of the

Ni-doped ZnO samples annealed at 600oC have been characterized by X-ray diffractometer (XRD), Scanning electron

microscope (SEM) and Vibrating sample magnetometer (VSM). The average crystalline size was calculated using

Debye-Scherrer’s formula. The particle size was found to be in the range of 36 to 42 nm. X-ray diffraction patterns

revealed that the crystal structure of samples corresponds to hexagonal wurtzite ZnO phase along with an additional

diffraction peaks linked to NiO and metallic Ni. SEM micro-image confirmed the presence of spherical Zn1-xNixO

nanoparticles. VSM measurement shows the hysteresis loop at room temperature which confirms the ferromagneticproperty of the samples. The origin of ferromagnetism in the samples could be due to the exchange interaction between

Ni2+ ions.

KEYWORDS: Zn1-Xnixo Nanoparticles, Ni-Doping, Diluted Magnetic Semiconductor, Magnetic Properties, Spintronics

INTRODUCTION

Diluted magnetic semiconductors (DMS) have attracted much attention in recent years because it is a type of

semiconductor in which fraction of host cations can be easily replaced by magnetic ions in order to achieve the objective of

fabricating spintronics devices such as spin-valve transistor.[1-4] ZnO is a group II-IV semiconductor and has become one of

the most promising candidates for DMS materials.[5] Moreover, ZnO have potential applications in optoelectronics due to

its, wide band-gap (3.3 eV) and high exciton binding energy (60 meV) properties. Scientists are investigating the effect of

doping ZnO with transition metals such as Fe, Co and Mn. [6-13]. A number of experiments have been carried out to

investigate the structural and magnetic properties of Ni-doped ZnO.[14-18] Experimental studies conformed that the

ferromagnetism strongly depends on synthesis techniques and environmental conditions used for the preparation of

samples. Various chemical methods have been developed to prepare nanoparticles of different materials of interest. Most

of the ZnO nanocrystals have been synthesized by traditional high temperature solid state reaction method. However this

method is time consuming and properties of the product can’t be controlled. ZnO nanoparticles can be prepared on a large

scale at low cost by simple solution based methods, such as chemical co-precipitation, hydrothermal reaction, and sol-gelsynthesis.

International Journal of SemiconductorScience & Technology (IJSST)ISSN(P): 2250-1576; ISSN(E): 2278-9405Vol. 5, Issue 2, Jun 2015, 1-10© TJPRC Pvt. Ltd.



2 Raminder Preet Pal Singh, I.S. Hudiara,Sudhakar Panday & Pushpendra Kumar

Impact Factor (JCC): 4.1875 Index Copernicus Value (ICV): 3.0

In the present work, we have synthesized Zn1-xNixO nanoparticles using modified sol-gel method. This is a simple

and low cost method and gives good yield of the end product and takes less time in preparing the nanoparticles. In this

research work we have studied the effect of dopant ion concentration on the structure and magnetic properties of Ni doped

ZnO (Zn1-xNixO (x = 0.01, 0.03, 0.05 and 0.07) annealed at 600

o

C.EXPERIMENTAL PROCEDURE

Nanocrystalline Zn1-xNixO (x = 0.01, 0.03, 0.05) semiconductors were synthesized by a simple modified sol-gel

method. Zinc Acetate (Zn-(CH3COO)2 .2H2O) and Nickel Acetate (C4H6NiO4.4H2O) were taken according to the

calculated stoichiometric ratio in a beaker containing 100ml distilled water. NaOH mixed in distilled water was added

drop-wise during the experiment in order to maintain pH of the solution at 10. The solution was then stirred at room

temperature for 2 h followed by aging for 24 hrs at the same temperature. After aging, precipitate that formed was filtered.

The product obtained at this stage was mixed Zinc and Nickel hydroxide powder. This compound was annealed at 600 0 C

for two hours and then grinded to obtain the final nanoparticles of Ni doped ZnO.

Figure 1: Schematic Diagram of Modified Sol-Gel SynthesisTechnique to Prepare Ni Doped Zno Nanoparticles

RESULTS AND DISCUSSIONS

XRD Analysis

X-ray diffraction analysis of all the samples was done using Brucker AXS diffractometer. X-ray diffraction

patterns of Ni doped ZnO show exhaustive evolution of hexagonal wurtzite phase in all the samples. Initially at low

concentration no peak corresponding to Nickel oxide was observed which confirmed no phase segregation i.e. perfect

incorporation of Ni. In all the samples peak intensity is very high which confirmed good crystalline formation. The

maximum peak intensity was observed corresponding to the plane (101). Initially as the Ni was incorporated, the intensityof peaks increased but at higher doping concentration it decreased. The maximum peak intensity was recorded in the



Effect of Ni-Doping on Structural and Magnetic Properties of ZnO Nanoparticles 3


Zn0.97Ni0.03O sample.

Figure 2: XRD Patterns of Pure Zno and Zn1−Xnixo (X = 0.01, 0.03,0.05, and 0.07) Nanoparticles Annealed at 600

It has been reported in literature that when any foreign particle is incorporated in the crystal lattice, it produces

strain as well as defects in the lattice which may reduce the crystal quality.[19] Figure 2, shows the shifting in peak which

was probably due to strain in the lattice. In doping, ionic radii plays an important role. If the ionic radii of foreign particle

are higher or lower than the host lattice, then lattice parameters of host expand or contract to accommodate it. Ionic radius

of Ni2+ (0.68 A°) is larger than that of Zn2+ (0.60 A°). So shifting of peaks towards lower angle suggests the incorporationof Ni in the ZnO lattice.[20] The average crystalline size was calculated by using scherrer’s equation (1) and was found to be

in the range of 36 nm to 42 nm as shown in table 1.

τ = k λ / B Cos θ (1)

Where, τ is grain size, B is the full width at half maxima and λ is the wavelength of X-ray used (1.548 Å) and θ is

the diffraction angle.

As Ni was incorporated, the crystalline size increased but when the Ni concentration was increased to 3% the

crystalline size was decreased which correlates with the XRD pattern. Doping causes enhanced nucleation growth which

supports the crystalline growth but at higher concentration, it causes distortion in the crystal lattice resulting in reduction in

crystallinity and size. The values of lattice strain are also shown in table I and are very low. The lattice parameters were

calculated using equation (2) given below.

(2) Where d, h, l, k, a and c are lattice constants.

The calculated values shown in table I, are very close to the reported values in literature. [21] At higher

concentration of Ni, a remarkable increase in dislocation density was also observed.





Table 1: Lattice Parameters of Pure ZnO and Zn1−Xnixo (X = 0.01,0.03, 0.05, and 0.07) Nanoparticles Annealed at 600

NiDoping%

ScherrerSize

LatticeStrain

d101 (Å)Spacing

Unit CellParameters c/aratio

DislocationDensity(10-3)linem-2 A C

0 % 39 nm 0.0027 2.4755 3.232 5.278 1.633 0.65

1% 39 nm0.0027

42.4755 3.232 5.278 1.633 0.65

3% 42 nm0.0025

42.4715 3.227 5.269 1.632 0.56

5% 40 nm0.0026

82.4755 3.232 5.278 1.633 0.62

7% 36 nm 0.0025 2.4781 3.235 5.283 1.633 0.77

Figure 3: Shifting of NiO Peak with the Doping Concentration of Zn1-Xnixo Samples Annealed at 600

On the other hand, with the increase in Ni concentration, an additional diffraction peak corresponding to NiO

(as shown in figure 3) appears at 2θ = 43.2°. This revealed that phase segregation has occurred in the samples. Also, with

increase in Ni concentration, the intensity of NiO peak increases and shifts to the lower angle which is an indication of

distortion of NiO to larger spacing where nickel gets oxidized and incorporated into ZnO lattice. [22] Apart from this peak,

a weak reflection at 2θ = 44.3° corresponding to Ni is also obtained.[27] Thus the XRD studies clearly indicate the presence

of Ni metal, apart from NiO, in the polycrystalline samples.

Scanning Electron Microscope (SEM) Analysis

For study of surface morphology, scanning electron microscope Carl Zeiss Supras 55 was used. Figures 4(a) & (b)

show SEM images of undoped and Ni doped ZnO. The SEM image of Zn0.99Ni0.01O confirmed that as synthesized material

is in nano range and in good agreement with calculated crystalline size from XRD.





Figure 4: SEM Image of (A) Pure Zno and (B) Zn0.99Ni0.01O Nanostructures

Ni incorporation was also confirmed by the EDAX analysis. The estimated values of Ni in ZnO are shown in table

2. From the table, it can be observed that %age of Ni incorporated in the samples is lower than their actual composition

incorporated during the synthesis process.

Table 2: EDAX Data of Ni-Doped ZnO Nanoparticle

Sample Ni % Zn % O % C %ZnO (Pure) -- 66.81 15.44 17.75

Zn0.99Ni0.01O 0.54 61.98 12.31 24.92Zn0.97Ni0.03O 2.11 72.81 11.94 11.38Zn0.95Ni0.05O 4.12 70.56 9.09 16.23

Zn0.93Ni0.07O 6.99 64.35 12.59 16.07

Vibrating Sample Magnetometer (VSM) Analysis

Magnetization measurements on the synthesized nanoparticles were carried out using Microsense E29 vibrating

sample magnetometer. All the measurements were made at room temperature. Pure ZnO sample shows no hysteresis curve

as shown in figure 5 (a), confirmed the diamagnetic property. Diamagnetic nature of pure ZnO has also been reported in

literature.[23]





(a)

(b) (c)

(d) (e)

Figure 5(A-E): Room Temperature Ferromagnetism of Undoped ZnO andDoped Zn1−Xnixo (X = 0.01, 0.03, 0.05, and 0.07) Nanoparticles

Whereas, from the magnetic hysteresis loops (M–H curve) for Ni doped samples i.e. Zn 1-xNixO (x=0.01, 0.03,

0.05 and 0.07) it is clear that all samples exhibit ferromagnetic behavior at room temperature. However, some researchers





observed ferromagnetism only at lower doping concentration (x < 0.05) but paramagnetic behavior for higher doping

concentration.[21] The values of saturation magnetization (Ms) and coercive field (Hc) of our Ni doped ZnO samples are

shown in the table 3.

Table 3: Magnetic Properties of Zn1-Xnixo (X=0.01, 0.03 0.05 and 0.07) NanoparticlesSample Hc (Oe) Ms (emu/g)

Zn0.99Ni0.01O 74 0.0216Zn0.97Ni0.03O 127 0.0135Zn0.95Ni0.05O 120 0.0157Zn0.93Ni0.07O 84 0.0145

So far, different models have been proposed [24-26] to explain mechanism responsible for the origin of

ferromagnetism in diluted magnetic semiconductors, but still this issue is controversial. Carrier-mediated ferromagnetism

can be possible model in order to explain the observed ferromagnetism in our samples. The origin of ferromagnetism might

be due to the formation of Ni-related secondary phase such as metallic nickel and NiO. From XRD pattern, it can be seen

that intensity of NiO peak increases with the increase in Ni concentration. Possibility of ferromagnetic behavior of samples

due to secondary phase NiO is ruled out as we know that bulk NiO is anti-ferromagnetic in nature above Neel temperature

of 520 K.[27]

From table 3, it is clear that the coercivty increases upto 127 Oe for 3% Ni-doped ZnO sample and for 5 and 7 at

% concentration value decreases to 120 Oe and 84 Oe which shows reduction in ferromagnetism. When the concentration

of Ni increases, carrier density decreases due to the compensation of oxygen vacancies, and as a result, ferromagnetism

decreases.[28] This fact revealed that Ni metal cluster as a secondary phase is not responsible for ferromagnetic behavior in

our samples. Thus, possibility of origin of ferromagnetism due to secondary phases in our samples is ruled out.

However, intrinsic defects such as oxygen vacancies and Zn interstitials, can usually act as shallow donors in

ZnO. Therefore, the room-temperature ferromagnetism in our samples could originate from the long-range Ni2+–Ni2+

ferromagnetic coupling mediated by shallow donor electrons.[22]

CONCLUSIONS

In the present study, Ni doped ZnO (Zn1-xNixO (x=0.01, 0.03 0.05 and 0.07)) diluted magnetic semiconductor

nanoparticles were successfully synthesized via simple modified sol-gel method. X-Ray diffraction pattern show formation

of hexagonal wurtzite structure in all samples of Ni doped ZnO along with secondary phases of metallic nickel an NiO. All

the samples of Zn1- xNi xO (x=0.01, 0.03 0.05 and 0.07) shows room temperature ferromagnetic behavior as observed fromthe M-H curves. Long-range Ni2+–Ni2+ ferromagnetic coupling mediated by shallow donor electrons could be the possible

reason for room temperature ferromagnetic behavior. The Ni doped ZnO nanoparticles of the present work having room

temperature ferromagnetism could be the suitable diluted magnetic semiconductors for Spintronic device applications.

REFERENCES

1.

Wolf, S. A., Awschalom, D. D., Buhrman, R. A., Daughton, J. M., Von Molnar, S., Roukes, M. L.,

Chichelkanova, A. Y., and Treger, D. M. (2001). Spintronics: A Spin-Based Electronics Vision for the Future.

Science , 294, 1488-1495.

2.

Ohno, H. (1998). Making Nonmagnetic Semiconductors Ferro- magnetic. Science, 281, 951-956.





3. Prinz, G. A. (1998). Magnetoelectronics. Science, 282, 1660-1663.

4.

Ghosh, S., & Mandal, K. (2010). Study of Zn1−xCoxO (0.02 < x < 0.08) Dilute Magnetic Semiconductor

Prepared by Mechanosynthesis Route. Journal of Magnetism and Magnetic Materials, 322 (14), 1979-1984.

5. Dietl, T., Ohno, H., Matsukura, F., Cibert, J., & Ferrand. Zener, D. (2000). Zener Model Description of

Ferromagnetism in Zinc- Blende Magnetic Semiconductors. Science, 287, 1019-1022.

6.

[Wesselinowa, J. M., & Aposto, A. T. (2010). A Possibility to obtain Room Temperature Ferromagnetism by

Transition Metal Doping of ZnO Nanoparticles. Journal of Applied Physics, 107, Article ID: 165202.

7.

Karmakar, D., Mandal, S. K., Kadam, R. M., Paulose, P. L., Rajarajan, A. K., Nath, T. K., Das, A. K., Dasgupta,

I., & Das, G. P. (2007). Ferromagnetism in Fe-Doped ZnO Nanocrystals: Experiment and Theory. Physical

Review B, 75, Article ID: 144404.

8.

S. K. Mandal, A. K. Das, T. K. Nath, D. Karmakar, and B. Satpati, “Microstructural and Magnetic properties ofZnO:TM (TM=Co, Mn) Diluted Magnetic Semiconducting Nano- particles”, Journal of Applied Physics. Vol.

100, Article ID: 104315. 2006.

9.

Martínez, B., Sandiumenge, F., Balcells, L., Arbiol, J., Sibieude, F., & Monty, C. (2005). Structure and Magnetic

Properties of Co-Doped ZnO Nanoparticles. Physical Review B, 72, Article ID: 165202.

10.

Duan, L. B., Rao, G. H., Yu, J., & Wang, Y. C. (2008). Ferro- magnetism of Lightly Co-Doped ZnO

Nanoparticles. Solid State Communications, 145, 525- 528.

11.

Luo, J., Liang, J. K., Liu, Q. L., Liu, F. S., Zhang, Y., Sun, B. J., & Rao, G. H. (2005). Structure and Magnetic

Properties of Mn-Doped ZnO Nanoparticles. Journal of Applied Physics, 97(8), Article ID: 086106.

12.

Wang, J. B., Huang, G. J., Zhong, X. L., Sun, L. Z., Zhou, Y. C., & Liu, E. H. (2006). Raman Scattering and High

Temperature Ferromagnetism of Mn-Doped ZnO Nanoparticles. Appled Physics Letters, 88(25), Article ID:

252502.

13.

Jayakumar, O. D., Gopalakrishnan, I. K., Sudakar, C., Kadam, R. M. & Kulshreshtha, S. K. (2007). Magnetization

and Structural Studies of Mn Doped ZnO Nanoparticles: Prepared by Reverse Micelle Method. Journal of Crystal

Growth, 300, 358-363.

14.

Bhuiyan, M.R.A., & Rahman, M.K. (2014). Synthesis and Characterization of Ni Doped ZnO Nanoparticles. I.J.Engineering and Manufacturing, 1, 10-17.

15.

Vijayaprasath, G., Murugan R., & Ravi, G. (2014). Structural, Optical and Magnetic Properties of Ni Doped ZnO

Nanostructures Prepared by Co-Precipitation Method. International Journal of ChemTech Research, 6(6), 3385-

3387.

16. Sarvari, K., and Tokeer, A., (2012). Synthesis, Optical and Magnetic Properties of Ni-Doped ZnO Nanoparticles.

Journal of Materials Science and Engineering, B2(6), 325-333.

17.

Jeevan, J., Mahesh, P., & Somnath, B. (2013). Ferromagnetic Ni-doped ZnO nanoparticles synthesized by a

chemical precursor method. Carbon – Sci. Tech., 5, 269-274.





18. John Kennady, S., Vethanathan, S., Perumal, S., Meenakshi Sundar, D., Priscilla Koilpillai, S., Karpagavalli, &

Suganthi, A. (2013). International Journal of Advanced Scientific and Technical Research, 6, 856.

19.

Faheem, A., Shalendra, K., Nishati, A., Anwar, M.S., Si Nae Heo, & Bon Heun Koo. (2012). Direct relationship

between lattice volume, bandgap, morphology and magnetization of transition metals (Cr, Mn and Fe)-doped ZnOnanostructures. Acta Materialia, 60, 5190-5196.

20.

Xu Linhua, & Li Xiangyin. (2010). Influence of Fe-doping on the structural and optical properties of ZnO thin

films prepared by sol–gel method. Journal of Crystal Growth, 312, 851-855.

21.

Huang, G. J., Wang, J. B., Zhong, X. L., Zhou, G. C., & Yan, H. L. (2007). Synthesis, structure, and room-

temperature ferromagnetism of Ni-doped ZnO nanoparticles. Journal of Material Science, 42, 6464-6468.

22.

Elilarassi, R., & Chandrasekaran, G. (2012). Synthesis, Structural and Magnetic Characterization of Ni-Doped

ZnO Diluted Magnetic Semiconductor. American Journal of Materials Science, 2(1), 46-50.

23.

Zhou, S., Potzger, K., Reuther, H., Kuepper, K., Skorupa, W., Helm, M. & Fassbender, J. (2007). Crystalline Ni

nanoparticles as the origin of ferromagnetism in Ni implanted ZnO crystals. J. Appl. Phys., 101.

24.

Venkatesan, M., Fitzgerald, C.B., & Coey, J. M. D. (2004). Thin films: unexpected magnetism in a dielectric

oxide. Nature, 430, 630.

25.

Sluiter, M. H. F., Kawazoe, Y., Sharma, P., Inoue, A., Raju, A. R., Rout, C., & Waghmare, U.V. (2005). First

Principles Based Design and Experimental Evidence for a ZnO-Based Ferromagnet at Room Temperature. Phys

Rev Lett., 94, Article ID: 187204.

26.

Eriksson, O., Bergqvist, L., Sanyal, B., Kudnovsky, J., Drchal, V., Korzhavyi, P. & Turek, I. (2004). Electronic

structure and magnetism of diluted magnetic semiconductors. J. Phys. Condens Matter, 16(48), Article ID: S5481.

27. Sasanka, D., & Pattayil Alias, J. (2005). Direct Observation of Ni Metal Impurities in Lightly Doped

Ferromagnetic Polycrystalline (ZnNi)O. Chem. Mater, 17, 6507-6510.

28.

Liu, X.X., Lin, F.T., Sun, L.L., Cheng, W.J., Ma, X.M., & Shi, W.Z. (2006). Doping concentration dependence of

room-temperature ferromagnetism for Ni-doped ZnO thin films prepared by pulsed-laser deposition. Appl. Phys

Lett., 88, Article ID: 062508.



Documents

1. Semi Conductor - Ijsst - Effect of Ni-doping on Structural and - Raminder Preet Pal Singh