SYNTHESIS AND CHARACTERIZATION OF MIXED FLUORIDES y1-xCa_a+1.5xF_7(-1.33 ≤ x ≤ 1.0)

摘要

In this paper, we report on the synthesis and characterization of the y1-xCa~2+l.5xF_7 (- l.33 ≤ x ≤ l.0) compounds and the phase equilibria in the CaF_2YF_3 system, in the continuation of our earlier studies on Sr and Ba analogues. It was found that the solubility limit of YF_3 in the CaF_2 lattice is about 33 mol/100 as compared to about 25 mol/100 of YF_3 in BaF_2 and SrF_2. The CaF_2YF_3 system shows the formation of an ordered cubic superstructure after the solubility limit. A hexagonal tysonite type phase separates out beyond 4l mol/100 of YF_3. A single phasic tysonite type product was obtained at the composition with about 75 mol/100 of YF_3, i.e., Y1.9Cao.65F_7