Evidence for a critical composition in group-IV–VI chalcogenide glasses

Experimental evidence for an ideal-glass composition in IV-VI chacogenide systems is obtained from high-pressure–low-temperature studies of Si-Te glasses. The electrical resistivity of bulk, melt-quenched ${\mathrm{Si}}_{\mathrm{x}}$${\mathrm{Te}}_{100\mathrm{-}\mathrm{x}}$ glasses (10≤x≤28) has been measured up to a pressure of 8 GPa and down to 77 K. All the glasses undergo sharp, discontinuous glassy-semiconductor–crystalline-metal transitions. The properties such as the transition pressure, the room-temperature atmospheric-pressure resistivity, and the activation energy for electrical conduction at different pressures show unusual variations at a composition x=20. The anomalous variations in properties observed at x=20 may be connected with the ideality of the glass occurring at this composition.