Anomalies of hypersound velocity and attenuation in ferroelectric tris-sarcosine calcium chloride (TSCC) for small-angle and right-angle Brillouinscattering and Brillouin backscattering
Wang, J. T.
Schmidt, V. Hugo
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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  phonons occurs somewhat below Tc seems to indicate that the anomalies are due to piezoelectric coupling induced by spontaneous polarization below Tc. For  phonons the elementary relaxation times which relate to the energy are estimated as τE0=5.25×10−13 sec above Tc and τE0=3.32×10−12 sec below Tc. The phonon attenuations are also estimated and compared with the observed ones. For the  phonons the elementary relaxation time is estimated as τ0=5.25×10−14 sec, in good agreement with the value obtained from right-angle Brillouin scattering.
J.T. Wang and V.H. Schmidt, â€œAnomalies of hypersound velocity and attenuation in ferroelectric trissarcosine calcium chloride (TSCC) for small-angle and right-angle Brillouin scattering and Brillouin backscattering,â€� Phys. Rev. B 34, 416-422 (1986)