A phenomenological theory of ultrasonic attenuation in ferroelectrics

The complex damping constant of an ultrasonic wave in a ferroelectric crystal which is non-piezoelectric above the Curie temperature was calculated in the hydrodynamic approximation. The interaction of the ultrasound with polarization waves is expressed in terms of electrostrictive constants. Ferroelectrics both of the relaxation and displacive type are treated in an unified way. The frequency and temperature dependence of the sound attenuation constant and frequency shift was studied in detail for two typical representatives of ferroelectrics, i.e. barium titanate and tri-glycine sulphate.The author gratefully acknowledges the help of Dr. L. Murtinová with some calculations.