Structural investigations of the xTeO2–(1−x)GeO2 (x=0, 0.2, 0.4, 0.6, 0.8 and 1) tellurite glasses: A composition dependent Raman spectroscopic study Original Research Article

Raman spectra of xTeO2–(1−x)GeO2 (x=0, 0.2, 0.4, 0.6, 0.8 and 1) germanium tellurite glasses were measured and analyzed in an effort to follow the structural changes caused by mixing two typical glass formers. Systematic Raman intensity measurements have been performed in an effort to elucidate the composition induced structural changes and a possible mechanism accounting for these changes was proposed. The network structure of the glass is characterized by TeO4 trigonal bipyramid mixed with TeO3 trigonal pyramid units, while GeO4 tetrahedral units are also present. Changing the GeO2 content results in the conversion of the TeO4 units to TeO3 units with a neutral doubly bridged oxygen atom, while the existence of charged terminal oxygen atoms is questionable. The measured relative Raman intensities are semi-quantitatively correlated to the transformation of the TeO4 trigonal bipyramid to TeO3 trigonal pyramids.