Moroccan Journal of Condensed Matter, Vol 9 (2007)

Study of Driving Forces for Atomic Migration in Dilute Alloys

Aditya M. Vora

Abstract


We present a pseudopotential calculation of the driving forces for atomic migration in the 156 dilute alloys of the 23 host of the different groups of the periodic table in the presence of electron currents. The forces on an atom arising from the applied electric field and from the electron scattering together comprise the driving force, causes a net current of atoms. A well recognized Ashcroft’s empty core (EMC) local model potential is used to investigate the driving forces for interstitial (FINT), vacancy (FVAC), substitutional (FSUB) and nearest neighbour (FNN) migration in dilute alloys. Five different types of the local field correction functions proposed by Hartree (H), Taylor (T), Ichimaru-Utsumi (IU), Farid et al (F) and Sarkar et al (S) are used to study the effect of the exchange and correlation on the aforesaid properties. The driving forces are calculated for interstitial, vacancy, substitutional and nearest neighbour migration in dilute alloys, and the results are found to compare qualitatively with most experimental data. The present study concludes that FINT is larger than FVAC. For some dilute alloys the electron scattering force is found in the opposite direction to the electron drift velocity. Present findings are compared with the other such data, which confirms the applicability of the model potential. Keywords: model potential, driving forces, atomic migrations, dilute alloys.