In situ high-temperature X-ray observation of structural changes of tellurite glasses with p-block oxides;: ZnO-TeO2 glasses

The thermal behavior of each of the three xZnO . (100 - x)TeO2 (where x = 10, 20 and 30 mol%) glasses was studied by an in situ high-temperature X-ray diffractometer, using a rapid measurement system, and differential thermal analysis (DTA). DTA results compared with X-ray diffraction data resulted in phase relations, at high temperature, of the three different glasses. The characteristic temperatures (glass transition and crystallization temperatures) determined for the three glasses showed a dependency on the ZnO content. In the three glasses, the alpha -TeO2 and ZnTeO3 were found to crystallize first, followed by the crystallization of ZnTe3O8. The phases observed at high temperatures in the three glasses were the same, except for an unknown phase found in the 30ZnO . 70TeO(2) glass. Existence-temperature ranges of the phases observed in the three glasses were found to be different. The relation between the first crystallization phase and the local structures of the ZnO-TeO2 glass systems is discussed. (C) 2001 Elsevier Science B.V. All rights reserved.