Effective migration energies associated with vacancies, divacancies and impurities

Abstract

Calculations of the effective migration energies for migrating vacancies and divacancies, as determined by the slope intersection method and by the method of combined isochronal and isothermal recovery, have been carried out. The effective migration energy is influenced by the change in equilibrium conditions associated with the changes in temperature together with the transient behavior involved. These transients are associated with interactions between vacancies and divacancies and also with their interactions with impurity atoms. When no impurities are present, the effect of these factors is to lower the effective migration energy, which would be observed experimentally, to values extending below that of either the single vacancy or divacancy migration energies. On the other hand, when impurities with sufficient concentrations of complexes are present, the effect of the transients is changed and the effective migration energy may range from that for the single vacancy to below that for the divacancy. effective migration energies were calculated over a range of vacancy, divacancy, and impurity concentrations, and the transition between the pure and impure behavior investigated. An analytic equation for the effective migration energy was obtained for the case of pure gold. However, there is generally no direct way of relating the observed migration energy, determined by either the slope intersection method or the combination isochronal-isothermal method, to the individual migration energies of the defects, but rather a more detailed analysis of the kinetics is necessary.