STRUCTURAL CHARACTERIZATION OF AG2GES3 GLASS BY ANOMALOUS WIDE-ANGLE X-RAY-SCATTERING

Germanium and silver atomic surroundings of Ag2GeS3 glass have been st udied by anomalous wide-angle x-ray scattering. The structural paramet ers deriving from the simulations of the differential distribution fun ctions, characterizing selectively Ge and Ag environments, show that t he medium-range order of the glass up to 5 Angstrom is close to that o f the crystallized reference alpha-Ag8GeS6. The absence of a first sha rp diffraction peak on the structure factor around Q = 1 Angstrom(-1). can be explained by the lack of Ge-Ge correlations in the medium-rang e order. Finally, these results allow us to discuss the validity of se veral structural models proposed to explain the ionic conduction in gl asses. [S0163-1829(97)08137-X].