Polarization fluctuations and transverse acoustic modes in a Rb_1-x(NH₄)_xH₂PO₄ glass

Transverse acoustic (1 0 0) phonons in Rb1-x(NH4)xH2PO4,x =0.25, have been measured by coherent inelastic scattering from 300 K to 10 K. They behave as those observed in Brillouin scattering. The model of piezoelectrically coupled modes which accounts for Brillouin spectra applies well to neutron data. © 1992.