Pressure-dependent Raman modes near the cubic-tetragonal transition in strontium titanate

KİRACI A., YURTSEVEN H. H.

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, vol.101, no.3, pp.1344-1355, 2018 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 101 Issue: 3
  • Publication Date: 2018
  • Doi Number: 10.1111/jace.15279
  • Journal Name: JOURNAL OF THE AMERICAN CERAMIC SOCIETY
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.1344-1355
  • Keywords: dielectric relaxation, phase transformations, Raman spectroscopy, strontium titanate, PHASE-TRANSITION, LANDAU THEORY, TEMPERATURE, SRTIO3, PEROVSKITES, BOUNDARIES, SCATTERING, PHONONS
  • Middle East Technical University Affiliated: Yes

Abstract

The pressure dependence of the Raman frequency shifts of various Raman modes is calculated at room temperature using the volume data from the literature for the cubic-tetragonal transition in SrTiO3. The isothermal mode Gruneisen parameters of those Raman modes are obtained, which decrease with increasing pressure for this molecular crystal. Calculated Raman frequencies are then used to predict the damping constant and the inverse relaxation time of those Raman modes as a function of pressure by means of the pseudospin-phonon (PS) coupled model and the energy fluctuation (EF) model to describe the cubic-tetragonal transition in SrTiO3. Also, the values of the activation energy are extracted for the Raman modes studied using both models (PS and EF). Our predicted damping constant and the inverse relaxation time for the Raman modes, can be compared with the experimental measurements close to the cubic-tetragonal transition in SrTiO3.