The semiconductor-metal transition of liquid arsenic-selenium mixtures at high temperatures and high pressures

The electrical conductivity sigma and thermoelectric power S of liquid As-Se mixtures (up to 40 at.% As) have been measured at high temperatures (up to 1500 degrees C) and high pressures (up to 1200 bar). For these mixtures, broad maxima appear in both the (partial derivative ln sigma/partial derivative P)(T) versus T and the(-partial derivative ln S/partial derivative P)(T) versus T curves, The maximum temperature T-max at which these maxima occur decreases monotonically up to 30 at.% As. Around T-max the semiconductor-metal transition occurs, which is enhanced by applying pressure. It was found that T-max increases as the As concentration changes from 30 to 40 at.% As. The results of EXAFS suggest a substantial change in the local atomic configuration around As atoms for 30 at.% As.