Electroacoustic Coefficients for Strontium Titanate in the Vicinity of Structural Phase Transition
A.Korobov, Yu.A.Brazhkin, N.I.Odina (Department of Acoustics, Faculty of Physics, M.V. Lomonosov Moscow State University, Moscow, Russia)
The results of experimental investigation of electroacoustic coefficients for strontium titanate single crystal in the vicinity of structural phase transition are presented. The measurements of relative change of 30-MHz-longitudinal wave velocity as a function of external electric field are carried out. Electric field is applied along or perpendicularly to the wave propagation direction. The linear additions to square-law dependence of ultrasound velocity as a function of electric field are observed by approaching to phase transition temperature in both cases. The linear addition is more significant when electric field is perpendicular to wave propagation direction. The linear addition appearance can be related to piezoelectric contribution which can be explained by a deviation of lattice symmetry from cubic that is stimulated by defects.
Section : 2