Light scattering studies in KTS and TGS

1) The low frequency Raman spectra of the ferroelastics KH 3 (SeO 3 ) 2 and its deuterated analogue have been measured. Broad Rayleigh wings are observed in the B 1g and B 3g symmetry spectra. The temperature evolution of the Raman spectra indicates that the phase transitions are of an order-disorder type. 2) The angular dependence of the Brillouin spectra in the uniaxial ferroelectric TGS has been studied. Both the frequency shift and the linewidth show appreciable anisotropic anomalies. The results are interpreted by the depolarization field effect on the polarization fluctuation.