LOCAL RANGE ORDER OF TELLURIUM ATOMS IN TEO2-BAO AND TEO2-BAF2 GLASSYSYSTEMS

The best synthesis conditions for (1-x)TeO2 + xBaO and (1-x)TeO2 + xBa F2 glasses of high and reproducible quality have been established, and their glassy region determined. Te L(III)-edge XANES (X-ray absorptio n near edge structures), Te L(III) and K-edge EXAFS (extended X-ray ab sorption fine structure) experiments were used to characterize the gla ssy network of these Ba-modified tellurite glasses. Addition of barium has been shown to induce a depolymerization of the TeO2 framework (br eaking of some Te-(ax)O(eq)-Te bridges), leading to partial transforma tion of TeO4+2E sites into TeO3+1E sites.