Structure of GeS2 glass studied by X-ray absorption spectroscopy and Reverse-Monte-Carlo analysis

We investigate the structure of glassy GeS 2 by combining Ge K-edge X-ray absorption spectroscopy with Reverse Monte Carlo modeling using the RMC-GnXAS method. Multiple-scattering EXAFS (Extended X-ray Absorption Fine Structure) analysis, together with neutron-diffraction (ND) based pair distribution functions, yields a three-dimensional atomic configuration compatible with both short- and medium-range order, improving previous determinations. Partial pair and bond-angle distributions are obtained and analyzed, and relevant structural parameters (coordination, average distances and angles) are evaluated. In particular, the first-neighbor peak of the Ge-S pair distribution is found much sharper than previously found. The shape of the bond-angle S-Ge-S distribution is found to be correlated to the occurrence of edge- and corner-sharing GeS 4 tetrahedra. This integrated RMC approach, combining EXAFS and ND-based data, is shown to provide a coherent structural description of the GeS 2 glass that links local bonding geometry to network topology.