DTA, DENSITY AND INFRARED-SPECTRA STUDIES OF THE STRUCTURE OF VANADIUM PHOSPHATE-GLASSES CONTAINING LITHIUM-OXIDE

The effect of replacing V2O5 by Li2O in vanadium phosphate glass sampl es was studied. Both infrared absorption spectra and differential ther mal analysis, in addition to density measurements were performed. It w as found that the number of oxygens increase in the network, also the vanadium ions are present in network forming positions, while lithium ions take only the interstitial positions. The transition temperature T-g and density were found to decrease with increasing Li2O content up to 15 mol% and then increase. The decrease was assumed to be related to the decrease in the mean crosslink densities, the increase of the n umber of nonbridging oxygens and mean bond strength. The final increas e may be attributed to the increase in the packing density of the stru cture.