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=50Å-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.