Prediction of elastic properties in oxide glasses: extension of Abd El-Moneim and Alfifi's approaches to lithium borovanadate glasses

An attempt has been made to predict the composition dependence of elastic properties in two series of lithium borovanadate glasses with molar compositions xLi(2)O-(90-x) B2O3-10V(2)O(5) (constant V2O5 series) and xLi(2)O-60B(2)O(3)-(40-x) V2O5(constant B2O3 series). The applicability of our recently presented semi-empirical formula, which correlates bulk modulus with the ratio between packing density and mean atomic volume is demonstrated for the two investigated glass series over a wide range of composition. The glass dissociation energy per unit volume has been calculated in terms of the basic structural units and the theoretical elastic moduli and Poisson's ratios have been evaluated on the basis of Makishima-Mackenzie's theory and compared with the experimental one. The results indicate that the ratio between packing density and mean atomic volume, fractal bond connectivity and molar volume play a dominant role in predicting the elastic properties and exploring changes in the structure of the glass. While the agreement between theoretical and experimental elastic moduli and Poisson's ratios is satisfactory for the constant B2O3 glass series, it is unsatisfactory for the majority of the samples of the constant V2O5 glass series. The discrepancy between theoretical and experimental values has been attributed to the lack of information about the concentrations of VO5 and VO4 groups, nonbridging oxygen atoms and V=O double bonds in all of the glasses.