Synthesis and characterization of mixed fluorides Y1−xCa2+1.5xF7 (−1.33 ≤ x ≤ 1.0)

In this paper, we report on the synthesis and characterization of the Y1−xCa2+1.5xF7 (−1.33 ≤ x ≤ 1.0) compounds and the phase equilibria in the CaF2–YF3 system, in the continuation of our earlier studies on Sr and Ba analogues. It was found that the solubility limit of YF3 in the CaF2 lattice is about 33 mol% as compared to about 25 mol% of YF3 in BaF2 and SrF2. The CaF2–YF3 system shows the formation of an ordered cubic superstructure after the solubility limit. A hexagonal tysonite type phase separates out beyond 41 mol% of YF3. A single phasic tysonite type product was obtained at the composition with about 75 mol% of YF3, i.e., Y1.9Ca0.65F7.