Nb2O5-TeO2 and Nb2O5-Li2O-TeO2 glasses: Evaluation of elastic properties

Elastic properties of xNb(2)O(5)-(1-x)TeO2 and 0.5xNb(2)O(5)-0.5xLi(2)O-(1-x)TeO2 glass systems were evaluated to understand the structural role of Nb2O5 and Li2O in the tellurite network. A correlation between elastic moduli and estimated compositional parameters has-been established on the basis of the bond compression model, Makishima-Mackenzie's theory and Rocherulle et al. model. Furthermore, the theoretical elastic moduli values are compared with the experimental values. Results revealed that, when Nb2O5 is added, NbO6 structural units and strong Te-O-Nb linkages are formed. The enhancement of elastic moduli is attributed to the increase in average cross-link density, ratio of packing density to mean atomic volume, dissociation energy per unit volume and stretching force constant of Nb-O-Te linkages. The discrepancy between experimental and theoretical results was explained in terms of the structural units which are formed in the tellurite network when TeO2 is substituted by Nb2O5 and Li2O.