Synthesis and structural investigations on TeO2-PbF2-CdF2 glasses and transparent glass-ceramics Original Research Article

New glasses have been prepared in the oxifluoride mixed system TeO2-PbF2-CdF2. Starting from pure TeO2 the addition of the fluorides leads to a decrease in the glasses characteristic temperatures. Also from Raman scattering results a structural evolution was observed where the number of structural units described as [TeO3] trigonal pyramids and [TeO3+1] polyhedra increases at the expense of the [TeO4] trigonal bipyramids supposed to exist in the TeO2 rich samples. Transparent glass ceramics were obtained from the glass with composition 80TeO2-10PbF2-10CdF2 (mol%) with the PbTe3O7 crystalline phase being identified by X-ray diffraction and EXAFS measurements performed at the Te K, Cd K and Pb LIII edges. Also from Exafs measurements it is proposed that cadmium ions are preferentially surrounded by oxygen atoms although they were in a fluoride anion environment in the starting material.