|About this Abstract
||Materials Science & Technology 2020
||Journal of the American Ceramic Society Awards Symposium
||Thermochemical Investigation of Lithium Borate Glasses and Crystals
||Alexandra Navrotsky, Lili Wu, Anastasia Koryttseva, Christoph B. M. Grob
|On-Site Speaker (Planned)
Lithium borate glasses and crystals with x = Li/(Li + B) of 0.2–0.5 have been synthesized by the quenching method. Their thermodynamics was analyzed by high–temperature oxide melt solutioncalorimetry. 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. 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 < x < 1) by a quadratic polynomial. The vitrification enthalpies were derived for x = 0.2 to 0.5 and ranged from 8.5 to 17.6 kJ/mol. The main factors controlling energetics are the strongly exothermic acid–base reaction between the network former (B2O3) and the network modifier (Li2O) and the formation of tetrahedrally coordinated boron.