Germanium and silver atomic surroundings of ${\mathrm{Ag}}_2{\mathrm{GeS}}_3$ glass have been studied by anomalous wide-angle x-ray scattering. The structural parameters deriving from the simulations of the differential distribution functions, characterizing selectively Ge and Ag environments, show that the medium-range order of the glass up to 5 Å is close to that of the crystallized reference $\alpha -{\mathrm{Ag}}_8{\mathrm{GeS}}_6.$ The absence of a first sharp diffraction peak on the structure factor around $Q=1\mathrm{}{\AA }^{-1},$ can be explained by the lack of Ge-Ge correlations in the medium-range order. Finally, these results allow us to discuss the validity of several structural models proposed to explain the ionic conduction in glasses.

• Received 17 March 1997

DOI:https://doi.org/10.1103/PhysRevB.56.10852