Light scattering in superionic glasses (AgI${)}_{\mathit{x}}$(${\mathrm{AgPO}}_3$${)}_{1\mathrm{-}\mathit{x}}$: Brillouin and Raman scattering

Brillouin and Raman-scattering experiments have been performed on the fast-ion conductor (AgI${)}_{\mathit{x}}$(${\mathrm{AgPO}}_3$ ${)}_{1\mathrm{-}\mathit{x}}$ in the full glass-forming region (0<x<0.55) from 18 to 330 K. We have been able to cover the full spectral range (0.2<ω<350 ${\mathrm{cm}}^{\mathrm{-}1}$) in this kind of solid-state sample by using the same spectrometer. The Raman spectra generally show a quasielastic scattering and two bumps centered at 30 and 110 ${\mathrm{cm}}^{\mathrm{-}1}$, with the last one being present only in the polarized configuration. By increasing the AgI content, the behavior of the Brillouin and Raman intensities together with the Raman spectral shape suggests the hypothesis that the Raman scattering of such glasses can be reconstructed by the sum of the pure α-AgI and ${\mathrm{AgPO}}_3$ spectra. Hence in these glasses the vibrational dynamics of pure α-AgI and ${\mathrm{AgPO}}_3$ seems to be weakly interacting with each other. Our data are compatible with the hypothesis that the structure of these glasses is formed by clusters of AgI dispersed in the ${\mathrm{AgPO}}_3$ host matrix.