Atomic-scale structures (pair correlation functions, anion-density distribution) and fluoride-ion diffusion in Ba1–xGdxF2+x solid solutions were investigated over a wide temperature range, which included the superionic transition, by performing molecular dynamics simulations using Born–Mayer–Huggins pair potentials. According to the results for x > 0.1, both the 4b (cubic site symmetry) and the 48i positions accommodated F interstitials (Fi-). Below the superionic transition, the migration of F- ions at low doping levels was dominated by non co-linear jumps between lattice and interstitial sites. Simulations confirmed that trigonal Gd3+-Fi- dipolar complexes predominated over tetragonal complexes. It was shown, by using a Monte Carlo simulation, that rare-earth ions in the solid solutions tended to aggregate.

Molecular Dynamics Simulations of Ba1–xGdxF2+x Solid Solutions over a Wide Temperature Range II - Structural Characteristics and Fluoride Ion Diffusion. I.Y.Gotlib, I.V.Murin, E.M.Piotrovskaya, E.N.Brodskaya: Inorganic Materials, 2003, 39[3], 291-8