Calcium cryolites

Abstract

In aluminium production, the electrolyte is a molten mixture of cryolite, alumina, aluminium fluoride and additives like calcium fluoride. When the electrolyte solidifies several phases appear, some of them known as `calcium cryolites'. In this paper we report the identification, empirical formulas and powder diagrams for three of them: NaF.AlF3.1.50CaF2 (form I); NaF.AlF3.CaF2 (form II); NaF.1.75AlF3.CaF2 (form III). The JCPDS Diffraction File Nos. are 36–1496 for NaF.AlF3.1.5CaF2, 36–1498 for NaF.AlF3.CaF2 and 36–1497 for NaF.1.75AlF3.CaF2.