A temperature dependence Raman study of the 0.1Nb2O5–0.9TeO2 glass-forming system

Raman spectra of the 0.1Nb2O5–0.9TeO2 binary glass-forming oxide system were measured over a temperature range including the glassy, supercooled and crystalline state to reveal the structural changes caused by temperature variation. The analysis of the reduced Raman spectra made it possible to quantitatively follow the transformation of the TeO4 trigonal bipyramids—that dominate in the low temperature glass—into TeO3 trigonal pyramids with temperature rise. Based on the predictions of existing structural models, we estimated with the aid of the Raman data the number of terminal oxygen atoms that inevitably accompany this structural change. The various crystal phases of the system studied in this work and the routes for converting one crystal phase into another were also examined. Finally, the low-energy excitations of the non-crystalline states of 0.1Nb2O5–0.9TeO2 were studied by following the temperature dependence of the Boson peak.