EXAFS MEASUREMENTS FOR LIQUID AS2SE3 AT HIGH-TEMPERATURES AND PRESSURES

Extended X-ray absorption fine structure (EXAFS) spectra from liquid As2Se3 around both the As and Se K-edges in the temperature-pressure range up to 1400-degrees-C and about 60 bar were measured. For the EXAFS measurements, a new type of high pressure vessel and a sample cell of own design made of polycrystalline sapphire were developed. Distinct EXAFS oscillations were obtained even at 1400-degrees-C. When the semiconductor-to-metal transition occurs at about 1000-degrees-C, the local environment around a central As atom is substantially changed and a new As neighbor site is induced.