EXAFS AT THE BILIII EDGE IN BI4GE3O12 AND IN XBI(2)O(3)-(100-X)GEO2 GLASSES

Extended X-ray absorption fine structure (EXAFS) measurements were mad e on crystalline Bi4Ge3O12 and xBi(2)O(3)- (100-x)GeO2 glasses at the BiLIII edge. Calculations of the EXAFS interference function, using th eoretical backscattering amplitude and phase functions, are consistent with the crystalline structure of Bi4Ge3O12 up to high Bi coordinatio n shells. Around bismuth atoms in glasses a large spread in the Bi-O b ond distances was found, and the Bi environment as seen by EXAFS is si milar to that observed in crystalline alpha-Bi2O3. The local structure in the glasses is independent of composition and does not change appr eciably for different quenching procedures. (C) 1998 Elsevier Science B.V.