Light scattering from phonons in TB2(MoO4)3

Raman and Brillouin spectra of Tb2 (MoO4)3 crystal have been measured in a wide temperature region from 77 to 500 K. Two soft A 1-modes determined by the anisotropic scattering tensor were found in the same frequency region. They broaden strongly with the insignificant frequency decrease as T ← Tc . The acoustic phonons anomaly near Tc including both the frequency shift and the damping of phonons was shown by Brillouin measurements. From Raman and Brillouin study one can suggest that there is a diffused central peak in the phase transition region.