Mode softening, precursor phenomena, and intermediate phases in PbZrO 3

Abstract

Single crystals of PbZrO3 have been studied by Brillouin light scattering, birefringence, and piezoelectric coefficient measurements. The structural phase transition at Tc is shown to be related to the softening of a longitudinal acoustic (LA) mode, whereas precursor effects are deduced from a central peak in the light scattering spectrum, finite birefringence, and piezoelectric coefficient above the structural instability. An intermediate phase in the vicinity of Tc is apparent where a coexistence of the LA mode with a high frequency mode appears, and in addition the transverse acoustic (TA) mode becomes visible. © 2013 American Physical Society.