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Abstract
Self-diffusion and ionic conduction via the interstitialcy mechanism in a simple cubic, binary random alloy AB were investigated as a function of composition using Monte Carlo simulation. It was found that allowance for non-collinear jumps (partly) replacing concurrent collinear site exchanges leads to a reduction in diffusion correlation effects. This goes along with a shift of the diffusion percolation threshold to lower concentrations of the (more) mobile component B. Even stronger changes of mass and charge transport compared to an exclusively collinear interstitialcy scheme are observed for additional contributions of direct interstitial jumps. It is remarkable that for both extensions of interstitialcy mediated diffusion, the Haven ratio appears to be greater than unity in certain composition ranges poor in B. All results rely on the calculation of tracer and interstitialcy correlation factors in the simplest possible three-dimensional lattice structure. Yet they may have more general relevance to the interpretation of tracer self-diffusion data and ionic conductivity measurements on crystalline materials.
Notes
No potential conflict of interest was reported by the authors.
1 Compared to our previous paper, we changed the notation of percolation thresholds from to
to avoid confusion with indices c referring to ‘collinear’ in the present work.
2 To reduce the number of indices, the common asterisk for labelling tracer diffusivity () has been replaced by the ‘hat’ symbol (
) throughout the paper.
3 Minor changes to Equation (Equation16(16) ) are necessary if the number of lattice sites and interstices are different.
4 In the terminology of LeClaire [Citation8], the present collinear and non-collinear jumps are denoted as direct and indirect interstitialcy jumps