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 SrTi03 is investigated by ultrasonic measurements of attenuation, velocity shifts, and stress dependence of the transition temperature T, . A method is described by which measurements of domain attenuation are used to correct the velocity data below T,. 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 aphenomenological 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, is predicted to be dT,/dp = 0. 5 x 10 K/dyn cm . Critical effects in sound velocity and attenuation are briefly described.

X-Ray Absorption Spectroscopy of Strontium(II) Coordination

“…Phase changes with temperature appear to have no effect on strontium coordination in this set of compounds. For example, SrTiO 3 (s) undergoes a ferroelastic phase transition (so-called "soft mode") from a cubic to a tetragonal space group at T c = 105 K. Previous work has shown that this does not affect unit cell volume or significantly change atom positions around strontium, consistent with our fit results (29,37,38).…”

Cubic to Tetragonal Phase Transition of SrTiO3 under Epitaxial Stress: An X-Ray Backscattering Study

“…The CT transition temperature T a is known to be pressure dependent. Measured by different groups, this dependence of T a was found to be 17 K/GPa [40], 29 K/GPa [41,42], and 5 K/GPa [42] for hydrostatic pressure, and 180 K/GPa under uniaxial pressure [40] by ultrasonic resonance. We can relate these values to the effect of the epitaxial stress on the transition temperature in our case.…”

Amplitude-Dependent Internal Friction in SrTiO 3 in a Vicinity of the Ferroelastic Phase Transition

“…Though the elastic and anelastic properties of the SrTiO 3 crystal in a vicinity of T C are investigated within more than 25 years [2][3][4], however, experiments were in most cases carried out at high frequencies ( f > 10 MHz). Only recently a number of papers was published [5][6][7], in which acoustic properties of SrTiO 3 were studied using low frequency experiments ( f = 1-20 Hz).…”