Diffusion in binary mixtures: An analysis of the dependence on the thermodynamic factor

DI PIETRO MARTÍNEZ, M.; HOYUELOS, M.

Physical Review E

American Physical Society

Año: 2019 vol. 100

2470-0045

We study the diffusion process in binary mixtures using transition probabilities that depend on a mean-field potential. This approach reproduces the Darken equation, a relationship between the intrinsic and the tracer diffusion coefficients, DA and DA∗, through the thermodynamic factor φ (a function of the derivative of the activity coefficient against the molar fraction). The mean-field approach allows us to go beyond the Darken equation and separately specify the dependence of DA and DA∗ on the thermodynamic factor. We obtain that φ appears in the expression for DA∗, but the intrinsic diffusivity DA turns out to be independent of φ. Experimental results taken from the literature on diffusion in metal alloys are consistent with this theoretical prediction.