Optical and Related Properties of Inorganic nanoparticles

Abstract

Many modern technologies have advanced to the point that the relevant fea- ture size is on the order of a few to a few hundreds of nanometer. At the fundamental level, there is an urgent need to better understand the prop- erties of materials on the nanoscale level. At the technological front, there is a strong demand to develop new techniques to fabricate and measure the properties of nanomaterials and related devices. One of the most fascinating and useful aspects of nanomaterials is their optical properties. This thesis contains the results of the experiments carried out to study the optical and related properties of inorganic nanoparticles and is divided into seven parts. Part-1 of the thesis gives a brief overview of inorganic nanomaterials presenting their optical properties and related applications relevant for the studies carried out in the subsequent parts. Part 2 deals with the results of investigations of ZnO nanoparticles and is divided into three sections. In section 1, the studies of changes in the band edge of ZnO nanoparticles doped with Mn, Co, and Ni are discussed along with their magnetic properties. Section 2 presents studies of photo- luminescence and photoconducting properties of colloidal ZnO nanoparticles annealed in an oxygen atmosphere at various temperatures. Section 3 con- tains results of studies on the photoconductivity of ZnO-graphene nanocom- posites. xi Part 3 of the thesis, comprising two sections, contains results of investi- gations of GaN nanoparticles. Section 1 deals with the synthesis and optical properties of In doped GaN nanoparticles. White-light emission character- istics of nanocomposites based on GaN nanoparticles are examined in the second section. Part 4 deals with the studies based on ReO3 nanoparticles. Surface en- hanced Raman scattering (SERS) from molecules adsorbed on nanoparticles of metallic ReO3 is presented in Section 1. Section 2 presents studies of e ect of these nanoparticles on the performance of silicon solar cell. Part 5 presents the e ect of refractive index of the medium on the lumi- nescence bands of nanophosphors. Part 6 contains results of optical spectro- scopic studies of composites of conducting polyaniline with CdSe and ZnO nanoparticles. In Part 7, a Raman study of the phase transition in KHSO4 is presented.