EXAFS studies of liquid arsenic chalcogenides

EXAFS measurements for liquid As-Se and As-Te mixtures have been carried ou t on the As, Se and Te K-edges. For liquid As40Te60 it is found by curve fi tting analysis that there exist homopolar As-As and Te-Te bonds, This is in contrast with liquid As40Se60 in which the full chemical order is preserve d. The coordination numbers around As and chalcogen atoms for both liquid A s-Se and As-Te mixtures decrease as temperature increases. At high temperat ure the network structure formed by three-fold coordinated As atoms and two -fold coordinated chalcogen atoms transforms into a chain-like structure, w here the semiconducting mixtures show metallic behaviors.