Infra-red spectra of crystalline phases and related glasses in the TeO2-V2O5-Me2O system

The crystal line phases Me₂O·V₂O₅·2TeO₂ (Me=Li, Na, K, Cs, Ag) and their glasses are studied with the aid of infra-red spectroscopy. The radial distribution function (RDF) curves of two glasses, Na₂O·V₂O₅·2TeO₂ and Cs₂O·V₂O₅·2TeO₂, are obtained by an X-ray diffraction study. An attempt is made to identify the main bands in the infra-red spectra of the crystalline compounds and the glasses. The absorption bands in the 970 to 880 cm^–1 range are assigned to the stretching modes of the VO₂ isolated groups. A trend is observed towards a shift of the high-frequency band by the replacement of an alkaline ion with another in the order Ag⁺, Cu⁺, Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, which is explained by their different polarizing ability. With the aid of X-ray diffraction studies it is shown that the basic structure units in the glasses studied are the VO₄ and TeO₄ groups.