Local range order of tellurium atoms in TeO2–BaO and TeO2–BaF2 glassy systems

Abstract

The best synthesis conditions for (1 –x)TeO₂+xBaO and (1 –x)TeO₂+xBaF₂ glasses of high and reproducible quality have been established, and their glassy region determined. Te L_III-edge XANES (X-ray absorption near edge structures), Te L_III and K-edge EXAFS (extended X-ray absorption fine structure) experiments were used to characterize the glassy network of these Ba-modified tellurite glasses. Addition of barium has been shown to induce a depolymerization of the TeO₂ framework (breaking of some Te–_axO_eq–Te bridges), leading to partial transformation of TeO_{4 + 2}E sites into TeO_{3 + 1}E sites.