Synthesis and characterization of Ba1−xNdxF2+x (0.00 ≤ x ≤ 1.00)

A series of mixed fluorides with general composition Ba_1−xNd_xF_2+x (0.00≤x≤1.00) was prepared by vacuum heat treatment of the mixture of starting fluorides, and analyzed by powder XRD. From the XRD analysis, the low temperature phase equilibria in BaF₂-NdF₃ system is elucidated. The initial compositions in this series, that is, up to the nominal composition Ba_0.65Nd_0.35F_2.35 (x≤0.35) exist as cubic fluorite-type solid solution. Beyond the solid solution limit, that is, x>0.35, a rhombohedral fluorite related ordered phase is observed. Further, NdF₃-rich compositions (x≥0.50) exist as a mixture of rhombohedral ordered phase and NdF₃ (tysonite)-type phase. About 10 mol% of BaF₂ could be retained in the NdF₃ lattice, forming a tysonite-type solid solution, under the short annealed and slow cooled conditions.