Structural Characteristics and Electrical Conductivity of Vanadium-doped lithium Ultraphosphate Glasses

Glasses of the 33.5Li₂O-66.5P₂O₅-xV₂O₅ (mol. %) system with (0 ≤ x ≤ 5) were prepared by the normal melting and annealing technique. Their physical and spectroscopic properties such as X-ray powder diffraction (XRD), density, infrared spectroscopy and electrical conductivity were investigated. The composition dependent density shows an initial decrease at 0.1 mol.% of V₂O₅ followed by an increase in density with further addition of the V₂O₅ content. The structure of these glasses has been studied by recording the Fourier-transform infrared spectroscopy (FTIR) over the range 400–1800 cm^?1. Vibrational modes are assigned to different types of phosphate groups in the glass network. The temperature (333–452 K) and composition dependence of direct current (DC) electrical conductivity were measured. The electric conductivity is observed to increase with the first addition of vanadium oxide reflecting the presence of V⁴⁺ions that take part within modifying positions in the glass network .Then, the electric conductivity is found to decrease with the further increase in the content of V₂O₅ up to 5 mol.% reflecting the formation of V⁵⁺ions that take part as network forming positions in the glass network. The variations in density and electrical conductivity with V₂O₅ content are discussed in terms of changes in the glass structure.