![Sample our Physical Sciences journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/110819/TOC-Subject-Sample-2021-Physical-Sciences.jpg"})
Abstract
A complex perovskite-type single crystal Na1/2Bi1/2TiO3 (NBT) with a cubic-tetragonal-trigonal sequence of phase transition, ending in a ferroelectric state, has been studied by Raman scattering. In additional to a possible soft mode which softens far below the phase transition, a broad central component has been revealed in a form which let us analyze the temperature dependence of its intensity. The central component has features of a relaxation mode with the highest intensity in the intertransirion region, so it arises from a critical light scattering on fluctuations of two coupled order parameters. The correlations between the central component behaviour, acoustic anomalies and dielectric response as well as their relation to a model with competing interactions are discussed. It is suggested that the broad central peak component in light scattering is characteristic of the relaxor-type ferroelectrics with a sequence of phase transformation irrespective of whether transitions are really observed as in NBT or whether transitions are frustrated at normal conditions as in PbMg1/3Nb2/3O3 (PMN).
