Calcium cryolites

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.