Heat of formation and transition temperatures of solid lithium hexafluoaluminate

Abstract

Calorimetric determination of the heat of the reaction 3LiF(c)+ AlF₃(c)= Li₃AlF₆(c) gave ΔH^°_r298=–5.4±0.5 kcal/mole^–1. With this value and the heats of formation of the constituent fluorides the heat of formation of Li₃AIF₆ becomes ΔH^°_f298. Li₃AIF₆(c)=–805.9±2.5 kcal. Five solid forms of Li₃AIF₆ have been indentified by high-temperature X-ray powder photography and transition temperatures have been estimated.