Synthesis and structural investigations on TeO2-PbF2-CdF2 glasses and transparent glass-ceramics
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Data
2002-04-01
Autores
Silva, MAP
Messaddeq, Younes [UNESP]
Briois, V
Poulain, M.
Villain, F.
Ribeiro, SJL
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Elsevier B.V.
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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 80TeO(2)-10PbF(2)-10CdF(2), (mol%) with the PbTe3O7 crystalline phase being identified by X-ray diffraction and EXAFS measurements performed at the Te K, Cd K and Pb L-III 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. (C) 2002 Published by Elsevier B.V. Ltd.
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Journal of Physics and Chemistry of Solids. Oxford: Pergamon-Elsevier B.V., v. 63, n. 4, p. 605-612, 2002.