Brillouin scattering study of the elastic anomalies in TGS atT>Tcunder uniaxial stress

Abstract

Abstract Brillouin spectra of TGS under moderate uniaxial stress along the ferroelectric b-axis at and above the transition temperature (Tc ) show a small shift in Tc and slight changes in the elastic constants. It is shown that a detailed analysis of previous data on thermal expansion αjj (T), dielectric constant ϵ22(T) and elastic constants Cjj (T) at zero stress allows one to make estimates of the third order elastic constants Cjj , which, in turn, permits an evaluation of (dC 22/dX 2) at T ∼ Tc , in rough agreement with our data for uniaxial stress X 2 < 2.5 × 108 dyn/cm2.