Mechanical Relaxation and Nonlinearity in Strontium Titanate Single Crystals

The temperature dependence of the resonance frequency of longitudinally vibrating [;100] bars of SrTiO3 single crystals exhibits two maxima atTa = 103 °K and Tb = 30 °K. Between these temperatures exact measurements are only possible if the exciting voltage is sufficiently low. At higher amplitudes nonlinear response can be observed. The maximum at Ta is shifted to higher temperatures by applying a uniaxial stress P (dTa/dP = 18 × 10−3 deg/at) and hydrostatic pressure p (dTa/dp = 1.5 × 10−3 deg/at). After changing the mechanical and electric bias, mechanical relaxation occurs in the temperature range between 30 and 80 °K.