An assumed concentration dependence of the formation energy of vacancy-type defects in solids was applied to the estimation of defect interaction parameters. The effective vacancy-type defect interaction was described by using a mixing potential. The sign of this potential characterized the stability of the so-called vacancy-type defect plus atom alloy. The ability of this approach, to describe the stability of such a vacancy-atom alloy, was illustrated for the case of Nb.

D.Fuks, S.Dorfman: International Journal of Quantum Chemistry, 1996, 57[5], 881-6