High resolution Brillouin scattering studies of β<i>-</i>Gd₂(MoO₄)₃; the bulk and surface phase transitions

Abstract

We present here results of Brillouin scattering from bulk and surface phonons propagating in a well known ferroelectric–ferroelastic crystal β-Gd2(MoO4)3, in the temperature range covering the phase transition. Temperature dependences of the velocity of Rayleigh surface acoustic waves, propagating in a few planes of this crystal, have been calculated. The surface phonon velocities determined experimentally have been found to show a different character of temperature dependences, especially in the phase transition range.