EXAFS Studies of Liquid Arsenic Chalcogenides

EXAFS measurements for liquid As-Se and As-Te mixtures have been carried out on the As, Se and Te K-edges. For liquid As4Te60 it is found by curve fitting analysis that there exist homopolar As-As and Te-Te bonds. This is in contrast with liquid As40Se6 in which the full chemical order is preserved. The coordination numbers around As and chalcogen atoms for both liquid As-Se and As-Te mixtures decrease as temperature increases. At high temperature the network structure formed by threefold coordinated As atoms and two-fold coordinated chalcogen atoms transforms into a chain-like structure, where the semiconducting mixtures show metallic behaviors.