Structural transformation yielding an unusual metallic state in liquid As2S3 under high pressure

The As2S3 melt at room pressure represents a liquid having a three-dimensional network structure, semi-conducting properties, and a huge viscosity. We have found that under high pressure a considerable change in the medium and short-range structure of this liquid is observed. Intermediate-range order correlations in the atomic arrangement almost disappear under pressure and an increase in the coordination number is observed. This increase is evidently associated with the formation of a significant fraction of the wrong neighbors As-As. At pressures above 6 GPa, the As2S3 melt has a conductivity close to the minimum conductivity value of similar to 100 Ohm(-1) cm(-1) and a moderate viscosity of similar to 0.5-1 Pa s. Obviously, the transition under high pressures to such "strange metallic" liquids are bound to be seen in many other chalcogenide melts with network structure.