Acoustical properties of disordered ferroelectrics

Abstract
A short review of acoustic properties of a number of disordered ferroelectric materials is made. In the first place such characteristics as velocity of ultrasound elastic waves and their attenuation in a phase transition range are discussed. We show that rather wide class of compounds (relaxators) can be identified as correlated (cluster) polar glasses. Experimental data for such materials are interpreted naturally while suggesting strong critical fluctuations and an extremely wide spectrum of relaxation times.