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

The electrical conductivity σ and thermoelectric power S of liquid As-Se mixtures (up to 40 at.% As) have been measured at high temperatures (up to 1500°C) and high pressures (up to 1200 bar). For these mixtures, broad maxima appear in both the (∂ In σ/∂P)T versus T and the (-∂In S/∂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.