Raman Spectroscopic Investigations of Nanoparticles of Sn _x Ti_1−x O₂ Solid Solution

SnO₂ nanoparticles dispersed in TiO₂ matrix are prepared at a relatively low temperature of ∼185 °C. Nanoparticles of Sn _x Ti_1−x O₂ solid solution without significant aggregation have been prepared by annealing them at ∼500 and 900 °C. X-ray diffraction and high-resolution transmission electron microscopy studies have clearly established the nano-size nature of the samples. Raman spectroscopic investigations of these samples show mixed vibrational modes, some of them being similar to TiO₂ (A_1g, E _g), while some of them are similar to SnO₂ (B _2g). The E_g mode shows significant red shift and B _2g mode shows significant blue shift. Unlike this A _1g mode remains unaffected. These results are explained based on the combined effects of random alloy formation and the nano-size nature of samples.