Role of vanadium oxide on the lithium silicate glass structure and properties
Anuraag Gaddam, Amarnath R. Allu, Hugo R. Fernandes, George E. Stan, Cătălin Negrila, Atul P. Jamale, François Méar, Lionel Montagne, J.M.F. Ferreira
Abstract
Abstract The structural role of V in 28Li 2 O–72SiO 2 (in mol%) lithium silicate glass doped with 0.5 mol% V 2 O 5 was assessed using 29 Si and 51 V Nuclear Magnetic Resonance (NMR), Fourier‐transform infrared (FTIR), and X‐ray photoelectron (XPS) spectroscopy techniques. Despite the low amount of V 2 O 5 used, the structural information obtained or deduced from the statistical analysis of the NMR data could explain the evolution of glass properties after V 2 O 5 addition. The XPS results indicated that all vanadium exists in 5+ oxidation state. Both the 29 Si NMR and FTIR data point toward an increase in the polymerization of the silicate network, caused by the V 2 O 5 acting as network former, capable to form various tetrahedral units (for n = 0, 1, and 2) in the glasses. These units, which are similar to phosphate units, scavenge the Li + ions and cause the silicate network to polymerize. However, in an overall balance, the entire glass network is depolymerized due to the additional nonbridging oxygens contributed by the vanadium polyhedra. The addition of vanadium causes the network to expand and increases the ionic conductivity.