EXAFS分光法によるGeO₂-P₂O₅系ガラスの局所構造研究

抄録

The Ge EXAFS (extended X-ray absorption fine structure) above its K absorption edge was measured for GeO₂-P₂O₅ glasses containing up to 49mol% PO_5/2 (here, chemical formula is defined as PO_5/2). The Ge-O distance was determined to be 1.72-1.76Å by the curve fitting method. It was shown that a part of Ge atoms changes their coordination number from 4 to 6 on introducing P₂O₅ into GeO₂ glass. The fraction of six-coordinated Ge atoms (N₆) was estimated from the Ge-O distances obtained by EXAFS analysis and the result agreed with the value of N₆ estimated from molar volume using partial molar volumes of V_p=24.20, V_Ge(4)=28.71 and V_Ge(6)=19.60cm³. N₆ approximately followed a formula N₆=x/2(1-x), where x is the molar fraction of PO_5/2.