SYNTHESIS, CHARACTERIZATION AND STUDIES ON OPTICAL PROPERTIES OF ZnS-Si02 NANOCOMPOSITES

Abstract

Nanocomposite consists of a matrix to which nanoparticles are added to improve a particular material property such as electrical conductivity, optical clarity, thermal stability, etc. ZnS-Si02 nanocomposite is widely used in electronic devices, specifically, in light emitting diodes and also' in biological labeling due to its excellent photo stability. ZnS-Si02 nanocomposites have been synthesized by different methods such as Rf sputtering, micro-emulsion and wet chemical method. Most of these methods are costly and complex. In the present study, a simple sol-gel synthesis of ZnS-Si02 nanocomposite has been investigated. In the sol-gel method, the chemical elements become uniformly distributed during gel formation and production of ultrafme particle with small crystallite size at lower temperature can be achieved. For the synthesis of ZnS-Si02 nanocomposites, zinc acetate and thioacetamide were taken in 1:1 molar ratio and then a mixture of ethanol, toluene and tetraethyl orthosilicate were added. This was followed by the addition of ammonia solution along with a small amount of distilled water. The obtained gel-was dried at 80°C. Mn doped ZnS-Si02 nanocomposites were also obtained by the same procedure by adding zinc acetate and manganese acetate with different mole ratios (90:10, 95:05, 98:02). The XRD patterns of the composites showed peaks due to only ZnS because Si02 is amorphous. The DRS spectra of the composites showed the characteristic absorption bands of ZnS-Si02. hi Mn doped ZnS-Si02 nanocomposites, the band gap increased in comparison to pure ZnS and ZnS-Si02 nanocomposites. FE-SEM images of ZnS-Si02 and Mn doped ZnS-Si02 nanocomposites showed agglomeration of spherical shaped nanoparticles. EDXA analysis also confirmed the presence of elements (Zn, S, 0, Mn and Si). The photoluminescence spectra of ZnS-Si02 nanocomposites showed the emission bands of ZnS. The present method is an easy method to synthesize ZnS-Si02 and Mn doped ZnS-Si02 nanocomposites at low temperature.