Synthesis and characterization of Ba1−xErxF2+x (0.00≤x≤1.00)

A series of mixed fluorides with general composition Ba1−xErxF2+x (0.00≤x≤1.00) were prepared by a vacuum heat treatment of the binary fluorides and analyzed by powder XRD, which revealed the phase equilibrium in BaF2–ErF3 system. The nominal compositions with x≤0.25 compositions exist as cubic fluorite type solid solution. A rhombohedral ordering is observed in the vicinity of 42 mol% of ErF3 in BaF2. A monoclinic phase with the composition Er2BaF8 dominates the ErF3-rich compositions. The compositions for x>0.67 exist as a mixture of Er2BaF8 and leftover ErF3, whereas the compositions for x<0.67 exist as a mixture of Er2BaF8 and rhombohedral fluorite derived phase. The evolution of the various phases will be discussed in reference to the powder XRD data.