Anomalous temperature dependence of prepeak in the superionic glass (AgI)x(AgPO3)1−x

Neutron diffraction studies are reported on the prepeak of the superionic conducting glass (AgI)x(AgPO3)1−x as a function of temperature in the glassy and supercooled-liquid phases. The glass structure consist of regions of amorphous silver phosphate network and of silver iodide. The prepeak reflects structure in the phosphate network with periodicity d=10Å. Its intensity shows anomalous behaviour at a temperature 6–11% above the calorimetric glass transition Tg.