Interpretation of mechanical properties and structure of TeO2-Li2O-B2O3 glasses

Lithium borate glasses containing TeO2 as Li0.6 Te x B1.4-2x O2.4-x have been prepared by the conventional rapid quenching method over a wide range of composition (x=0, 0.1, 0.2, 0.3, and 0.35). Ultrasonic velocities (longitudinal and shear) were measured in these glasses at room temperature. The elastic moduli, and the Debye temperature, were calculated and discussed quantitatively in terms of the glass transition temperature, the cross-link density, and the packing density. The monotonic decrease in the velocities, the glass transition temperature, and the elastic moduli as a function of TeO2 modifier content reveals the loose packing structure, which is attributed to the increase in the molar volume and the reduction in the vibrations of the borate lattice. The compositional dependence of these parameters suggested that TeO2 changes the rigid character of Li0.6B1.4O2.4 to a matrix of ionic behavior bonds by breaking down the lithium borate structure. This was attributed to the creation of more and more discontinuities and defects in the glasses