The investigation of low-frequency acoustic properties of ferroelectrics and ferroelastics by torsion pendulum technique

The features of infrasonic frequency (10-3-10-1 Hz) internal friction, Q-1, and shear modulus, G, in different ferroelectric and ferroelastic crystals have been studied using the inverse torsion pendulum technique over a wide temperature range and different external fields which lead to the change of a real crystal structure. It is shown that the anomalous behavior of Q-1 and G at infralow frequencies to a great extent depends on crystal lattice imperfections (dislocations, point defects, domain and interphase boundaries). Physical mechanisms responsible for this behavior are discussed.