The Crystallographic and Optical Studies on Cobalt Doped CdS Nanoparticles

Vishnu R. Huse, Vishwanath D. Mote, Babasaheb N. Dole

Advanced Materials Research Laboratory, Department of Physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad, India.

DOI: 10.4236/wjcmp.2013.31008                

Abstract

The samples of Cd_{1 － x}Co_xS with compositions x = 0.0 & 0.6 were prepared by Co-precipitation route at room temperature. XRD analysis confirms that the samples have cubic structure with no impurity phases. The lattice parameter, volume cell, X-ray density and grain size were calculated using XRD data. It is found that lattice parameter, volume of unit cell and X-ray density decrease with enhancing Co content. It is due to the smaller ionic radius of Co than the Cd. It is well noticed that the grain size increases with increasing Co content, it may be owing to the good synthesis technique. The functional groups and chemical interaction were determined by FTIR spectra. From FTIR spectra, it is investigated that absorption bands show the presence of resonance interaction between vibrational modes of oxide ions in the crystal. The energy band gap of Co doped CdS samples was calculated using UV-Vis analysis. It is observed that energy band gap decreases with increasing Co content owing to the sp-d exchange interaction between Co and CdS atoms.

Keywords

Nanocrystals; Chemical Synthesis; Grain Size; FTIR Spectra

1. Introduction

Recently, diluted magnetic semiconductors (DMS) have attracted considerable attention owing to their potential applications in spintronics. They can exploit both the spin and the charge of degree of freedom which promise new functionality of memories, detectors, and light emitting sources [1,2]. These materials have large number of applications in the fields of solar cell, microelectronics, catalysis, optical communications and light emitting diode [3,4]. On the other hand, Cadmium sulfide (CdS) is an important semiconductor compound of the II-VI group with excellent physical properties and band gap of 2.4 eV. Cadmium sulfide is an interesting material for optoelectronic device applications and has been extensively studied in light emitting diodes, photocatalysis, biological sensors, solar cells and photo degradation of water pollutants [5-10]. It is observed that Li & Eu doped CdS Nanomaterials are studied widely in the reported literature [11-17].

In this paper, we report the crystallographic and optical studies of of Co doped CdS nanoparticles. The Co doped CdS samples were characterized by X-ray diffracttion (XRD), Fourier transmission infrared (FT-IR) spectroscopy & UV-Vis spectra.

2. Experimental

The samples of Cd_1−xCo_xS nanoparticles with concentration x = 0.0 & 0.06 were prepared by Co-precipitation route. The chemicals cadmium acetate, thioacetamide, cobalt nitrate were dissolved in 50 ml of ethyl alcohol in separate beakers and stirred for 1 h with the help of magnetic stirrer. After 1 h the solution of cobalt nitrate was added drop wise in the solution of cadmium acetate and kept for 30 minutes. Then the solution of thioacetamide was added into the mixture of cadmium acetate and cobalt nitrate. This solution again stirred for 1 h, filtered using a filter paper and then washed with ethanol to remove impurity present in it. The residue was collected and dried at room temperature. After that each sample is ground for 15 min.

3. Results and Discussion

3.1. XRD Study

Figure 1 shows XRD patterns of samples are recorded at room temperature. XRD patterns of the samples reveal that they have cubic structure with no extra peaks of impurity phases. This suggests the material is in single phase form with homogeneous powder of finer particle size. The peak intensity goes on decreasing with increasing Co concentration.

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	S. A. Wolf, D. D. Awschalon, J. M. Daughton, S. Von Molnar, M. L. Roukes, A. Y. Chtchelkanova and D. M. Tregewr, “Spintronics: A Spin-Based Electronics Vision for the Future,” Science, Vol. 294, No. 5546, 2001, pp. 1488-1495. doi:10.1126/science.1065389
[2]	H. Ohno, “Making Nonmagnetic Semiconductors Ferromagnetic,” Science, Vol. 281, No. 5369, 1998, pp. 951-956. doi:10.1126/science.281.5379.951
[3]	M. Nirman and L. Brus, “Luminescence Photophysics in Semiconductor Nanocrystals,” Accounts of Chemical Research, Vol. 32, No. 5, 1999, pp. 407-414. doi:10.1021/ar9700320
[4]	R. C. Ahoori, “Electrons in Artificial Atoms,” Nature, Vol. 379, No. 1, 1996, pp. 413-419. doi:10.1038/379413a0
[5]	D. L. Klein, R. Roth, A. K. L. Lim and A. P. Alivisatos, “A Single-Electron Transistor Made from a Cadmium Selenide Nanocrystals,” Nature, Vol. 389, No. 6652, 1997, pp. 699-701. doi:10.1038/39535
[6]	V. Ruxandra and S. Antohe, “The Effect of the Electron Irradiation on the Electrical Properties of Thin Polycrystalline CdS Layers,” Journal of Applied Physics, Vol. 84, No. 2, 1998, pp. 727-733. doi:10.1063/1.368129
[7]	V. L. Kolvin, M. C. Schlamp and A. P. Alivisatos, “LightEmitting Diodes Made from Cadmium Selenide Nanocrystals and a Semiconducting Polymer,” Nature, Vol. 370, No. 6488, 1994, pp. 354-357. doi:10.1038/370354a0
[8]	N. Romeo, A. Bosio and A. Romeo, “An Innovative Process Suitable Toproducehigh-Efficiency CdTe/CdS ThinFilm Modules,” Solar Energy Materials Solar Cells, Vol. 94, No. 1, 2010, pp. 2-7. doi:10.1016/j.solmat.2009.06.001
[9]	A. P. Alivisatos, “Semiconductor Clusters, Nanocrystals, and Quantum Dots,” Science, Vol. 271, No. 5251, 1996, pp. 933-937. doi:10.1126/science.271.5251.933
[10]	S. Bachir, K Azuma, J. Kossanyi and P. Valat, “Photoluminescence of Polycrystalline Zinc Oxide Co-Activated with Trivalent Rare Earth Ions and Lithium. Insertion of Rare-Earth Ions into Zinc Oxide,” Journal of Luminescence, Vol. 75, No. 1, 1997, pp. 35-49. doi:10.1016/S0022-2313(97)00093-8
[11]	S. Tiwari and S. Tiwari, “Development of CdS Based Stable Thin Film Photo Electrochemical Solar Cells,” Solar Energy Materials & Solar Cells, Vol. 90, No. 11, 2006, pp. 1621-1628. doi:10.1016/j.solmat.2005.01.021
[12]	C. B. Murray, D. J. Norris and M. G. Bawendi, “Synthesis and Characterization of Nearly Monodisperse CdE (E = Sulfur, Selenium, Tellurium) Semiconductor Nanocrystallites,” Journal of the American Chemical Society, Vol. 115, No. 19, 1993, pp. 8706-8715. doi:10.1021/ja00072a025
[13]	X. Peng, J. Wickham and A. P. Alivisatos, “Kinetics of II-VI and III-V Colloidal Semiconductor Nanocrystal Growth: ‘Focusing’ of Size Distributions,” Journal of the American Chemical Society, Vol. 120, No. 21, 1998, pp. 5343-5344. doi:10.1021/ja9805425
[14]	H. Zhang, X. Fu, S. Niu, G. Sun and Q. Xin, “Luminescence Properties of Li+ Doped Nanosized SnO2:Eu,” Journal of Luminescence, Vol. 115, No. 1-2, 2005, pp. 7-12. doi:10.1016/j.jlumin.2005.02.008
[15]	Y. Qian, K. Hara, H. Munekata and H. Kukimoto, “BlueEmitting Ac-Electroluminescent Cells Based on ZnS:Tm, Li Powder Phosphors,” Japanese Journal of Applied Physics, Vol. 34, No. 3B, 1995, pp. L368-L370. doi:10.1143/JJAP.34.L368
[16]	J. C. Ronfard-Haret and J. Kossanyi, “Electroand Photoluminescence of the Tm3+ Ion in Tm3+and Li+-Doped ZnO Ceramics. Influence of the Sintering Temperature,” Chemical Physics, Vol. 241, No. 3, 1999, pp. 339-349. doi:10.1016/S0301-0104(98)00431-5
[17]	V. D. Mote, V. R. Huse, K. M. Jadhav, B. N. Dole and S. S. Shah, “Synthesis and Structural Properties of Mn Doped ZnO Nanoparticles by Ceramic Route,” Bionano Frontiers, 2010, pp. 145-150.
[18]	A. M. Abdeen, O. M. Hemeda, E. E. Assem, M. M. ElSehly, “Structural, Electrical and Transport Phenomena of Co Ferrite Substituted by Cd,” Journal of Magnetism and Magnetic Materials, Vol. 238, No. 1, 2002, pp. 75-83. doi:10.1016/S0304-8853(01)00465-6
[19]	A. Patterson, “The Scherrer Formula for X-Ray Particle Size Determination,” Physical Review, Vol. 56, No. 10, 1939, pp. 978-982.
[20]	P. Koidl, “Optical Absorption of Co2+ in ZnO,” Physical Review B, Vol. 15, No. 5, 1977, pp. 2493-2499. doi:10.1103/PhysRevB.15.2493
[21]	M. Thambidurai, N. Muthukumarswami, D. Velauthapillai, S. Agilan and R. Balasundaraprabhu, “Structural, Optical and Electrical Properties Cobalt Doped CdS Quantum Dots,” Journal of Electronica Materials, Vol. 41, No. 4, 2012, pp. 665-672. doi:10.1007/s11664-012-1900-5