Structure of barium chloride-oxide tellurite glasses

Abstract New barium chloride-oxide tellurite glasses, BaCl 2 – BaO – TeO 2 , are studied by means of quantum-chemical modeling and Raman spectroscopy and a model of glass network is developed. The model allows one to relate the glass structure and vibrational properties (in particular, vibrational frequencies and Raman intensities) with the glass composition. Continuous network of barium chloride-oxide tellurite glass is proved to be formed mainly by structural groups of three types, TeO 4 trihedral bipyramids, O 2 Te O trihedral pyramids and O 3 Te – O - tetrahedra. No structural groups of any other type are necessary for the continuous network being built. Barium and chlorine atoms form no covalent bonds in the glass network occurring as Ba 2 + and Cl - ions in interstitial sites. Interpretation of Raman spectra of barium chloride-oxide tellurite glasses in the 550 – 850 cm - 1 range is suggested. In particular, the Raman band near 760 cm - 1 characteristic of these glasses is shown to be caused by both stretching vibrations of Te O double bonds of nonbridging oxygen atoms in O 2 Te O groups and stretching vibrations of Te – O - bonds of negatively charged nonbridging oxygen atoms in O 3 Te – O - groups. The model can be applied to analyze vibrational spectra of barium chloride-oxide tellurite glasses of various compositions.