Electric field gradient in dilute alloys of aluminum

Abstract

The electric field gradient $q$ and asymmetry parameter $\ensuremath{\eta}$ are calculated for $\mathrm{Al}\mathrm{Mg}$, $\mathrm{Al}\mathrm{Si}$, $\mathrm{Al}\mathrm{Cu}$, $\mathrm{Al}\mathrm{Zn}$, $\mathrm{Al}\mathrm{Ga}$, $\mathrm{Al}\mathrm{Ge}$, $\mathrm{Al}\mathrm{Ag}$, and $\mathrm{Al}\mathrm{Cd}$ alloys. The Alfred and Van Ostenburg charge perturbation, which accounts for both the asymptotic and preasymptotic regions, is used to evaluate the valence-effect contribution. The size-effect contribution is calculated in the elastic continuum model proposed by Sagalyn and Alexander. It is found that the valence effect alone cannot explain the observed $q$ and $\ensuremath{\eta}$. The size-effect contribution is found larger than the valence-effect contribution for all the alloys except for $\mathrm{Al}\mathrm{Ag}$ for which the valence-effect contribution is found larger than the size-effect contribution. The calculated values of $q$ and $\ensuremath{\eta}$ are found to be in close agreement with the experimental values and exhibit an improvement over other available theoretical results.