Acoustic studies of imperfect TGS crystals

In order to elucidate the role of lattice defects in the acoustic properties of ferroelectrics near the second-order phase transition, the comparative studies of the temperature dependences of the velocity and absorption coefficient of ultrasound for model TGS crystals with various structural imperfections were made. The effects of conversion to the single-domain state and of plastic deformation on the acoustic properties were examined. The temperature dependence of the permittivity was also measured. The results found for TGS with point defects were explained within phenomenological models. The differences between the temperatures of maximum sound absorption and maximum permittivity were explained in terms of broadened phase transitions.