Anomalies of hypersound velocity and attenuation in ferroelectric tris-sarcosine calcium chloride (TSCC) for small-angle and right-angle Brillouin scattering and Brillouin backscattering

Abstract

The Brillouin spectra of ferroelectric tris-sarcosine calcium chloride have been observed using small-angle and right-angle scattering and also backscattering. For different-frequency phonons along the same direction, analogous anomalies in the sound velocity and the attenuation are seen. The smallest angle we have achieved is 7.48°. The temperature and frequency dependences of the sound velocity are discussed. The fact that the linewidth maximum for [001] phonons occurs somewhat below $T_c$ seems to indicate that the anomalies are due to piezoelectric coupling induced by spontaneous polarization below $T_c$. For [010] phonons the elementary relaxation times which relate to the energy are estimated as ${\tau }_0^E$=5.25×${10}^{\mathrm{-}13}$ sec above $T_c$ and ${\tau }_0^E$=3.32×${10}^{\mathrm{-}12}$ sec below $T_c$. The phonon attenuations are also estimated and compared with the observed ones. For the [001] phonons the elementary relaxation time is estimated as ${\tau }_0$=5.25×${10}^{\mathrm{-}14}$ sec, in good agreement with the value obtained from right-angle Brillouin scattering.