| Abstract |
In this work, new glass compositions in the TeO2-GeO2-Nb2O5-K2O system have been prepared and studied. The germanotellurite glasses were prepared by melt-quenching and their density, refractive index and characteristic temperatures have been determined. The structure of these glasses has been studied by infrared and Raman spectroscopies. The progressive replacement of TeO2 by GeO2 led to an increase of the glass transition and crystallisation temperatures of the glasses and a simultaneous decrease of their density and refractive index. Typical density and refractive index values of these glasses ranged from 4.98 to 3.85 g cm(-3) and 2.08 to 1.79, respectively, with increasing GeO2 content. The infrared spectra are dominated by a band similar to 640 cm(-1) in the tellurite glass and similar to 800 cm(-1) in the germanate glass. The Raman spectra of the germanotellurite glasses present an intense boson peak between similar to 34 and 47 cm(-1), together with high frequency peaks at similar to 670 cm(-1) and similar to 470 cm(-1) for high tellurite and high germanate glass compositions, respectively. The vibrational spectra of these germanotellurite glasses indicate that the glass network consists basically of TeO4 and [TeO3]/[TeO3+1] units, mixed with GeO4 and NbO6 polyhedra. (C) 2011 Elsevier B.V. All rights reserved. |
