Comparison of Acoustic Behaviors Between the Perovskite and the Tungsten-Bronze Uniaxial Relaxors

Abstract

The longitudinal acoustic mode behaviors of three cubic perovskite relaxors and one tungsten-bronze uniaxial relaxor were compared in a widest temperature range by Brillouin scattering. All investigated relaxors exhibited substantial softening of the Brillouin shift upon cooling and a sudden increase in the hypersonic damping at a temperature lower than the Burns temperature, from which four characteristic temperatures were defined in relation to the temperature evolution of polar nanoregions. The Brillouin shift of the uniaxial Sr_0.61Ba_0.39Nb₂O₆ relaxor showed a positive slope at temperatures above the Burns temperature, which indicates the existence of coupling between some persisting relaxation process and the acoustic waves propagating along the polar axis.

Acknowledgments

This research was supported by Basic Science Research Program Through the National Research Foundation of Korea(NRF) funded by the Ministry of Education, Science and Technology (2009-0070871).