**Effect of the thermodynamic factor on the intrinsic and tracer
diffusivities in binary mixtures**

MS Puelles and M Hoyuelos, PHYSICAL REVIEW E, 107, 024123 (2023).

DOI: 10.1103/PhysRevE.107.024123

One of the Darken equations gives a relationship between the intrinsic
and the tracer diffusion coefficients, DA and D*A, of species A in a
solid binary mixture. In its original formulation, the equation reads DA
= D*A , with the thermodynamic factor. The question addressed in this
paper is how DA and D*A depend separately on . Using a recent result
for transition probabilities in terms of the excess chemical potential
**M. Di Muro and M. Hoyuelos, Phys. Rev. E 104, 044104 (2021)**, it is
shown that the intrinsic diffusivity does not depend on . This approach
simplifies a previous theoretical analysis that reaches the same result.
Experimental results of diffusion in Ni-Pd and Fe-Pd alloys **M. J. H.
van Dal et al., Acta Mater. 48, 385 (2000)** are used to check the
theory. Numerical simulations of Ni-Pd were performed to show that the
migration energy is the main factor responsible for the increase in
diffusivity at intermediate concentrations.

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