Direct observation of the soft mode in the paraelectric phase ofPbTiO3by confocal micro-Raman scattering

Abstract

The soft mode behavior in ${\text{PbTiO}}_{3}$ (PT) single crystal has been revisited by our confocal micro-Raman measurements. Contrary to the common understandings, the temperature dependence of soft mode in the cubic PT paraelectric phase was precisely resolved for the first time, owing to the existence of macroscopic size Raman active regions $(\ensuremath{\ge}780\text{ }\text{nm})$. By evidently ruling out the possibility of defect-induced Raman scattering, the elasto-optical coupling serves as the most likely mechanism for the occurrence of these Raman active regions.