A STRUCTURAL STUDY OF THE MOLTEN BI2O3-GEO2 SYSTEM BY THE EXAFS METHOD

An atomic-scale structure of molten Bi4Ge3O12, Bi12GeO20 and Bi2GeO5 h as been studied by a newly constructed laboratory EXAFS spectrometer f or high temperature liquids. Both Ge K- and Bi L-edge absorption spect ra were obtained by the fluorescence X-ray detection mode. It was foun d from the present systematic experimental data that germanium atoms f orm GeO4 tetrahedra in the molten Bi2O3-GeO2 system with all compositi ons. On the other hand no distinct structure around bismuth atoms coul d be found. It is suggested that these results indicate that the struc tural feature of the molten Bi2O3-GeO2 system is a random mixing of Ge O4 tetrahedra, bismuth and oxygen atoms.