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Synthesis and structural investigations on TeO2-PbF2-CdF2 glasses and transparent glass-ceramics |
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| Authors: | MAP Silva Y MessaddeqV Briois M PoulainF Villain SJL Ribeiro |
| Institution: | a Instituto de QuÍmica, UNESP, C.P. 355, 14800-900, Araraquara, SP, Brazil b LURE, Bât. 209-d, Université Paris-Sud, BP 34, 91898, Orsay Cedex, France c CEMA, Université de Rennes I, 35042Rennes, France d LCIM2, Université Pierre et Marie Curie, 75 252 Paris Cedex 5 France |
| Abstract: | 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. |
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