Temperature Induced Structural and Photoluminescence Properties

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Mechanics, Materials Science & Engineering, April 2017 – ISSN 2412-5954

Temperature Induced Structural and Photoluminescence Properties of Poly Ethylene Glycol (PEG) Capped/Uncapped Cadmium Oxide Nanoparticles (CdO NPs)51 P. Lokanatha Reddy 1, S.K. Khadheer Pasha1, a 1 – Sensor Laboratory, Materials Physics Division, School of Advanced Sciences, VIT University, Vellore, Tamil Nadu, India a – khadheerbasha@gmail.com DOI 10.2412/mmse.31.67.343 provided by Seo4U.link

Keywords: cadmium oxide nanoparticles (CdO NPs), X-ray Diffraction (XRD), photoluminescence (PL).

ABSTRACT. Uncapped and PEG capped CdO NPs were successfully synthesized by precipitation technique. XRD and TEM studies were used to investigate the particles structure, size and shape. As synthesized samples showed major hexagonal Cadmium Hydroxide [Cd (OH)2] phase and were completely transformed into cubic CdO crystalline phase above 400 °C annealing temperature. A good crystallinity was noticed in PEG capped CdO NPs. TEM images brought out the information about the synthesized nanoparticles (NPs) existed spherical in shape. The weight loss from thermogravimetric analysis (TGA) graphs depicted the formation of CdO NPs from Cd (OH)2. PEG on CdO NPs evidently increased the direct band gap emission intensity around 480 nm and while indirect band gap emission intensity of around 620 nm was increased in uncapped CdO NPs. Beside this, PL spectra revealed interesting changes with the effect of PEG, annealing temperature and excitation wavelengths. Hence PL spectra ascertained their possible use for optical and electronic applications.

Introduction. CdO nanostructures have attracted considerable attention to various applications such as solar cells, photocatalytic and photodiodes due to its little electrical resistivity, high carrier concentration and high optical transmittance in the visible region [1]. CdO is an important n-type and II–VI semiconductor material with a direct band gap of 2.5eV and an indirect band gap of 1.98 eV [2, 3]. Due to dual band gap nature, CdO finds its potential applications in the field of optoelectronic devices [4]. Being convenient to synthesis NPs, the chemical precipitation method was selected due to low production cost, higher yield rate, low temperature maintenance and easy performance at any climate [5]. It is known that size of the NPs and crystalline structure can be restricted easily through the use of surfactants in the synthesis process of the system. Various surfactants (CTAB, PVP, PEG) can alter the shape, size and other surface properties to different extent depending upon their molecular structure of NPs. It is reasonable that short chain polymers can also promote the formation structure of nanosystems [6]. In the current study, PEG is found to be selectively promoting the formation of CdO NPs. From literature survey there is no report available on systematic investigation of structural and PL properties of PEG capped CdO NPs. Hence we were reporting the effect of PEG and annealing temperature on optimization of structural and photoluminescence properties of CdO NPs. Experimental Synthesis procedure. The cadmium acetate dihydrate [Cd (CH3COO)2·2H2O], sodium hydroxide (NaOH) and PEG were the starting materials obtained from Sigma-Aldrich and used as received without further purification. First, cadmium acetate dihydrate added in the 100 ml of DI water to form 51

© 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/

MMSE Journal. Open Access www.mmse.xyz 227


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