Influence of nanoscale regions on Raman spectra of complex perovskites

Abstract

New approach on interpretation and processing of Raman spectra of complex perovskites is suggested. Raman spectra of $PbMg_{1/3}Nb_{2/3}O_{3}$ and $% PbSc_{1/2}Ta_{1/2}O_{3}$ are successfully described on the basis of the phonon-confinement model and validity of the method is demonstrated on good agreement of experimentally obtained and computer simulated spectra of another complex perovskite, $BaMg_{1/3}Ta_{2/3}O_{3}$. The study showed that the size of nanoscale regions is a kind of an inborn characteristic of the sample and is not temperature dependent. For $PbSc_{1/2}Ta_{1/2}O_{3}$, two special temperature points, approximately 400 K and 600 K are found from the analysis of the temperature behaviour of obtained mode parameters.