Reverse Monte-Carlo Analysis of neutron diffraction from AgI-Ag₂S-AgPO₃ superionic conducting glasses

Neutron diffraction patterns from silver phosphate (AgPO₃), AgI-AgPO₃ and Ag₂S-AgPO₃ glasses were analysed by the Reverse Monte-Carlo method. The diffraction patterns were collected on the HIT-II spectrometer at KENS up to Q = 50 Å^{- 1}. The derived structural models of the salt-doped glasses were compared to AgPO₃ glass to correlate features of the atomic and molecular structure with observed superionic conduction in these glasses. A structural model based on extended chains of PO₄ tetrahedra, as reported previously by other researchers, provides a solid basis for all these glasses. The analysis indicates a strengthening of the Ag-Ag correlations and contrasting changes in the Ag-O correlations in the doped glasses. We also conclude that S largely displaces non-bridging O in the PO₄ tetrahedra in Ag₂S-AgPO₃ glass.