Microstructural and Optical Properties of Ni doped CdS Nanoparticles Synthesized by Sol Gel route

Microstructural and Optical Properties of Ni doped CdS Nanoparticles Synthesized by Sol Gel route

Available online at www.sciencedirect.com ScienceDirect Materials Today: Proceedings 5 (2018) 20636–20640 www.materialstoday.com/proceedings ICMPC_...

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Available online at www.sciencedirect.com

ScienceDirect Materials Today: Proceedings 5 (2018) 20636–20640

www.materialstoday.com/proceedings

ICMPC_2018

Microstructural and Optical Properties of Ni doped CdS Nanoparticles Synthesized by Sol Gel route Hadeel Salih Mahdi*, Azra Parveen and Ameer Azam Department of Applied Physics, Z.H. College of Engineering & Technology, Aligarh Muslim University, Aligarh-202002, India

Abstract The nanoparticles of pure and Ni doped CdS were synthesized by sol gel route in aqueous medium. The obtained particles were characterized by X- ray diffraction studies (XRD). The results of structural characterization show the formation of pure and Ni doped CdS nanoparticles in single phase without any impurity. The morphological analysis was carried out by high resolution (TEM) studies. The optical absorption spectra of pure and doped sample recorded by UV-VIS spectrophotometer in the range of 350 to 800 nm have been presented and explained. The energy band gap as calculated by the Tauc relationship was found to increase with Ni doping. Ni doped CdS may found its major applications in solar cell, sensors and photo catalysis. © 2018 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of Materials Processing and characterization. Keywords: XRD, TEM, Optical Properties

1. Introduction Semiconducting chalcogenides nanoparticles, especially sulphides and selenides have been investigated widely, owing to their interesting opto-electronic properties [1, 2]. Amongst these chalcogenides nanoparticles CdS nanomaterials possessing a band gap of 2.42 eV and exhibiting remarkable electrical and optical properties are extensively used in solar cells, biological synthesis and photoconductors [3–6]. Metal ions doping, especially Ni2+ are demonstrated to control the band gap and absorption properties and are able to improve the photo activity of photocatalysis [7, 8]. Further, the incorporation of Ni2+ into the CdS lattice can provide them with interesting properties inherited from the synergetic effect and is expected to be possible because the radius of Ni2+ is smaller than that of Cd2+. Transition metal doped semiconductors also known as diluted magnetic semiconductors (DMSs)

* Corresponding author. E-mail address: [email protected] 2214-7853 © 2018 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of Materials Processing and characterization.

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[9, 10] have attracted much attention due to their potential applications in spintronics biological labels, LEDs, lasers, and bio-photonics [11, 12]. The surprising changes in the nanoscale DMS are due to their quantum confinement effects. Despite these advantages, not much work has been reported on Ni doped CdS nanoparticles. Thus, in this article we report about synthesis, structural and optical properties of Ni doped CdS nanoparticles by sol gel route. 2. Experimental Details Sol gel route was used for the synthesis of pure and Ni -doped CdS nanoparticles. All chemicals were of analytical grade purchased from Sigma-Aldrich and were used without further purification. Cadmium nitrate [Cd (NO3)2 .4H2O] , nickel nitrate [Ni (NO3)2 .6H2O] and sodium sulfide (Na2S) in the ratio of 1:1 were weighed according to the stoichiometric amount and dissolved in double distilled de-ionized water (100 mL). The pH of the solution was adjusted by adding ammonia solution. The aqueous solution of the precursor was then stirred in a beaker for 4 h at 80 ˚C in order to mix the solution uniformly. The transparent mixture transformed into yellowish orange color gradually which indicated the formation of Ni doped Cadmium sulfide nanoparticles. The stirred solution was then centrifuged for 20 minutes at 4000 rpm and a yellowish residue was obtained. The yellowish orange residue was then filtered and washed repeatedly with water (3 times) and ethanol (2 times) to remove any unreacted chemicals or impurities and then obtained product was extracted into a petri dish of ceramic and dried slowly in vacuum oven at 150˚C for 7 h. The final products obtained in the powder form were collected for characterization. 3. Results And Discussion 3.1. Micro Structural Analysis The XRD pattern of pure and Ni doped CdS nanoparticles are shown in Fig. 1. These nanoparticles were characterized by X-ray diffraction technique (XRD) in the 2 range of 200–800 (Rigaku Miniflex II) with Cu Kα radiations (λ = 1.54A˚) operated at voltage of 30 kV and current of 15 mA. The diffracted peaks obtained at diffraction angles 2 of 26.630, 43.880, 52.110 and 71.020 corresponds to the (002), (110), (200) and (114) planes of hexagonal Ni doped CdS. The matrix of Ni doped CdS indicates the dopant ions ought to be incorporated into the lattice as substitution ion. The powder patterns are in good agreement with the standard CdS JCPDS Card no. (JCPDS-80-0006).The unmodified hexagonal structure was obtained by the addition of Nickel ion into the CdS-NPs.

Fig.1. X-ray diffraction of pure and Ni doped CdS Nanoparticles

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The crystallite size of the Ni doped CdS nanoparticles were determined from the full width at half- maximum (FWHM) of the most intense peak making use of the Debye Scherrer equation [13] and found to be about 12 nm for pure CdS and 25 nm for Ni doped CdS. 3.2. UV-VISIBLE SPECTRA The absorption spectra of pure and Ni doped CdS nanoparticles recorded within the range 350−800 nm are shown in Fig. 2.The absorption peaks obtained confirms the blue shift when compared to the bulk material this is because of quantum confinement effect. Ni doped CdS has an absorbance peak at around 490 nm. The absorbance generally depends on several factors such as oxygen deficiency, band gap, impurity centers, grain size, lattice strain and surface roughness [14, 15].

Fig.2. Absorbance spectra as a function of wavelength for pure and Ni doped CdS

The optical band gap was determined by the Tauc relation [16] as shown in Fig. 3 and came out to be 2.67 eV for pure CdS and 2.84 eV for Ni doped CdS.

Fig.3. Band Gap of pure and Ni doped CdS

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3.3. Transmission electron microscopy (TEM) The morphological analysis was carried out by high resolution TEM studies. The morphological images of the pure and Ni doped CdS nanoparticles are shown in Fig. 4(a) and (b).The spherical shape is observed for Ni doped CdS. The average particle size determined by TEM histogram is equal to 9 nm for pure CdS and 16 nm for Ni doped CdS and no alteration in the size and shape is observed due to the amalgamation of Ni dopant. The particle size obtained from TEM analysis is comparable to the particle size as calculated by Debye–Scherrer’s formula from the XRD pattern. All the particles have homogeneous morphology.

Fig. 4 (a). TEM Analysis of pure CdS

Fig. 4 (b). TEM Analysis of Ni doped CdS

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Hadeel Salih Mahdi et al./ Materials Today: Proceedings 5 (2018) 20636–20640

Conclusions We have successfully synthesized pure and Ni doped CdS Nanoparticles by sol gel route. The confirmation of nanoparticles structure of pure and doped CdS was made through XRD data which shows the presence of all the main peaks. The optical band gap measures as 2.84 eV for Ni doped CdS. The TEM image reveals that synthesized sample was highly crystalline and in agglomerated form of NPs. Acknowledgements Authors are grateful to Department of Science &Technology (DST) and University Grant Commission (UGC), Government of India for providing financial support in the form of PURSE II and DRSII and Reference heading should be left justified, bold, with the first letter capitalized but have no numbers. Text below continues as normal. are grateful to the Chairman, Department of Applied Physics, Aligarh Muslim University for the financial support. References [1] N.V. Hullavarad, S.S. Hullavarad and P.C.Karulkar, Journal Nano science Nanotechnol.8, (2008)3272 . [2] Sana Riyaz, Azra Parveen, Ameer Azam, Perspective in Science 8, (2016) 632-635. [3] N. Romeo, A. Bosio, A. Romeo, Solar Energy Materials and Solar Cells 94, (2010)2–7. [4] M. Bruchez Jr., M. Moronne, P. Gin, S. Weiss, A.P. Alivisatos, Science (80). 281, (1998)2013–2016. [5] T. Gao, Q.H. Li, T.H. Wang, Applied Physics Letters 86, (2005)1–3. [6] Dong, L. H.; Liu, Y.; Zhuo, Y. J.; Ying Chu, Y. European Journal of Inorganic Chemistry 2010, (2010) 2504−2513. [7] Kudo, A.; Sekizawa, M. Chem. Communication 15, (2000)1371−1372. [8] W. Lee, S.K. Min, V. Dhas, S.B. Ogale, S.-H. Han, Electrochemistry Communication. 11, (2009)103–106. [9] H.S. Mahdi, A. Parveen, S. Agrawal, A. Azam, AIP Conf. Proc. 1832, (2017)050012. [10] X.W. Lou, L.A. Archer, Z. Yang, Adv. Mater. 20, (2008)3987–4019. [11] H. Ohno, Making Nonmagnetic Semiconductors Ferromagnetic, Science, 281, (1998)951–956. [12] J.K. Furdyna, Diluted magnetic semiconductors, J. Appl. Phys. 64, (1988)R29–R64. [13] A.L. Patterson, Phys. Rev. 56, (1939)978–982. [14] S. Agrawal, A. Parveen, A. Azam, J. Lumin. 184, (2017) 250–255. [15] S. Agrawal, A. Parveen, A. Azam, J. Magn. Magn. Mater. 414, (2016)144–152. [16] J. Tauc, Optical Properties of Amorphous Semiconductors, Amorph. Liq. Semicond., Springer US, Boston, MA, (1974)159–220.