Local order around tungsten atoms in tungstate fluorophosphate glasses by X-ray absorption spectroscopy

Abstract X-ray absorption spectroscopy was used to study the local environment of tungsten atoms in NaPO 3 –BaF 2 –WO 3 glasses and the results were compared with crystalline references Na 2 WO 4 and WO 3 . XANES measurements at the W-L 1 edge allowed to determine a distorted octahedral environment of tungsten atoms in these glasses similar to the local order of tungsten in monoclinic WO 3 . Extended X-ray absorption fine structure (EXAFS) has been used as a local probe to monitor the effect of WO 3 concentration on the tungsten environment. Based on an analysis of the EXAFS data, we proposed a three-shell model of oxygen atoms around tungsten as in monoclinic WO 3 . With increasing WO 3 concentration, it was found that R 2 decreases from 1.96 to 1.92 A whereas R 3 increases from 2.07 to 2.12 A.