Ultrasonic Propagation, Stress Effects, and Interaction Parameters at the Displacive Transition in SrTiO3

Abstract

The interaction between strain and order parameter at the structural transition in SrTi${\mathrm{O}}_3$ is investigated by ultrasonic measurements of attenuation, velocity shifts, and stress dependence of the transition temperature $T_a$. A method is described by which measurements of domain attenuation are used to correct the velocity data below $T_a$. Also, biaxial pressure has been successfully used to suppress the domain structure in the tetragonal phase. By comparing the experimental results with the consequences of a phenomenological configurational potential the interaction parameters are deduced. The model is found to correlate the experimental results in a consistent way. The hydrostatic-pressure dependence of $T_a$ is predicted to be $\frac{d{T}_a}{\mathrm{dp}}=0.5\mathrm{}\times {10}^{-9\mathrm{}}$ K/dyn ${\mathrm{cm}}^{-2\mathrm{}}$. Critical effects in sound velocity and attenuation are briefly described.