Ion transport and interatomic potentials in the alkaline-earth-fluoride crystals

Abstract

A comprehensive theoretical survey is reported of the mechanisms and energetics of ion transport in the alkaline-earth fluorides. Our calculations use new crystal potentials which provide a more reasonable description of the anion-anion interactions. This requires the substitution of a more flexible form of potential leading to marked improvements in the calculated defect energies. Also, mechanisms neglected in earlier work may play an important role in ion migration. Thus a non-defect-assisted process is suggested as an additional anion-transport mechanism. Cation migration in pure crystals may be predominantly via a divacancy process.