Elastic properties and fragility of lithium borate glasses

The elastic properties of lithium borate glasses, xLi(2)O center dot(100-x)B2O3, over a wide composition range tip to x=64 mol% Li2O have been investigated by Brillouin scattering spectroscopy (BSS). The longitudinal (V-L) and transverse (V-T) sound velocity and elastic moduli, i.e. longitudinal modulus (L), shear modulus (G), bulk modulus (K) and Young's modulus (E), have been determined as a function of the composition. They monotonically increase in the composition range 0 <= x <= 28, and then take nearly constant values for x>40 mol% Li2O. The correlation between the elastic properties of the glassy state and the fragility of the liquid state has been investigated. It is found that, except for the lower and higher composition ranges, there is a linear correlation of V-L, V-T, L and G to the fragility.