Our main interest is Raman, photoluminescence (PL) and infrared study (FTIR) of structural and optical properties of semiconductor nanopowders like anatase TiO2 which attracts much attention due to the numerous applications in photocatalysis, optical coatings and in chemical-biological hybrid nanocomposites; nanometric ceria powders doped with Y and Nd which are promising ceramic electrolytes for solid oxide fuel cells (SOFC) able to function at intermediate temperatures; nonoxide SiC, Si3N4 and SiCN composite nanopowders as well as their composites that belong to the group of advanced ceramic materials with excellent thermo-mechanical properties; Si nanoparticles embedded in SiOx thin films.
From the detailed study of the Raman modes in above mentioned materials we obtained the information about the size and shape of the nanoparticles, about the strain effects material stoichiometry and about the effects of surface states.
From the PL measurements of the oxide (SiO2, TiO2, ZnO, CeO2), carbide (SiC), and nitride wide band gap nanoscale materials we can probe the band gap and determine the mean diameter of these nanopowders. We used PL data to study crystallinity, stress and stoichiometry, impurity and defect states in these materials. Apart from these, we have also investigated PL properties of annealed SiOx thin films.
Using FTIR reflection spectorscopy we developed a theoretical model for proper determination of nanocomposite dielectric function in order to get the better insight into electron-phonon interaction, nature of the surface bonds and reactions occurring at the nanoparticle surface.
The detailed optical characterisation of these materials will help us in understanding how to improve the performances of the nanomaterials and nanostructures.