Thermochemical investigation of lithium borate glasses and crystals

Lithium borate (LB) glasses and crystals with x = Li/(Li + B) = mole fraction of Li2O of 0.2–0.5 have been synthesized by the quenching method. The thermodynamics of these materials were analyzed by high‐temperature oxide melt solution calorimetry. The formation enthalpies from oxides of glasses range from −33.6 to −67.3 kJ/mol and those of crystals range from −42.1 to −77.4 kJ/mol, where compositions are given on the basis of one mole of (Li2O + B2O3). The formation enthalpies of both glasses and crystals become more negative with increasing Li2O mole fraction up to 0.5. The enthalpies of formation of glasses can be fit over the entire composition range (0