New anion-conducting solid solutions Bi1-xTex(O,F)(2+delta) (x > 0.5) and glass-ceramic material on their baseстатья
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:The anion-excess fluorite-like solid solutions with general composition Bi1-xTex(O,F)(2+delta), (x > 0.5) have been synthesized by a solid state reaction of TeO2, BiF3 and Bi2O3 at 873 K with following quenching. The homogeneity areas and polymorphism of the I <-> IV Bi1-xTex(O,F)(2+delta) phases were investigated. The crystal structure of the low temperature IV-Bi1-xTex(O,F)(2+delta) phase has been solved using electron diffraction and X-ray powder diffraction (a = 11.53051(9) angstrom, S.G. la-3, R-I = 0.046, R-P = 0.041). Glass formation area in the Bi2O3-BiF3-TeO2 (10% TiO2) system was investigated. IVBi1-xTex(O,F)(2+delta) phase starts to crystallize at short-time (0.5-3 h) annealing of oxyfluoride glasses at temperatures above T-g (600-615 K). The ionic conductivity of the crystalline Bi1-xTex(O,F)(2+delta) phase and corresponding glass-ceramics was investigated. Activation energy of conductivity E-a = 0.41(2) eV for the IV-Bi1-xTex(O,F)(2+delta) crystalline samples and E-a = 0.73 eV for the glass-ceramic samples were obtained. Investigation of the oxyfluoride samples with a constant cation ratio demonstrates essential influence of excess fluorine anions on the ionic conductivity. (C) 2011 Elsevier B.V. All rights reserved.