Vacancy formation and migration energies in strained crystals

The formation and migration energies of vacancies in crystals under hydrostatic strain are considered in model fcc and bcc crystals using the technique of computer simulation. Equilibrium and non-equilibrium interatomic potentials have been employed for iron, molybdenum, copper and nickel. In the case of Ni, a simple density-dependence of the potential has also been incorporated. Significant differences between the potential forms and crystal structures are reported. For the purpose of comparison, Mukherjee's empirical relation between the formation energy and Debye temperature is exploited to obtain the variation of this energy with lattice parameter. By way of contrast, the effect of the vacancy migration energy of a neighbouring vacancy is also considered in the model crystals. (orig.)