Some new results on the ultrasonic behavior of SrTiO3 in the quantum paraelectric region

Results on the ultrasonic study of SrTiO₃ in the temperature range from 20 to 120 K using an electrostrictive interdigital transducer for longitudinal waves and piezoelectric transducer for shear waves are presented. A thermally activated relaxation loss mechanism due to strain-induced domain wall motion has been observed in the tetragonal phase of SrTiO₃. Below 40 K the anomalies in velocity and attenuation indicating the possible onset of Muller state have been found for both longitudinal and shear waves. The decrease of velocity has been connected with anomalous temperature behavior of elastic constant c₄₄, and peaks of attenuation could be explained by fluctuations