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Diffusion in binary mixtures: An analysis of the dependence on the thermodynamic factor
M Di Pietro Martínez1, M Hoyuelos1
1Instituto de Investigaciones Físicas de Mar del Plata (IFIMAR-CONICET), Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Deán Funes 3350, 7600 Mar del Plata, Argentina.
Physical Review. E
|October 3, 2019
Summary
This study reveals that intrinsic diffusivity in binary mixtures is independent of the thermodynamic factor, unlike tracer diffusion. This finding advances our understanding of diffusion processes in materials.
Area of Science:
- Physical Chemistry
- Materials Science
- Chemical Engineering
Background:
- Diffusion in binary mixtures is fundamental to many material processes.
- The Darken equation relates intrinsic (DA) and tracer (DA*) diffusion coefficients via the thermodynamic factor (Φ).
Purpose of the Study:
- To investigate diffusion in binary mixtures using a mean-field potential approach.
- To extend the Darken equation by separately analyzing the dependence of DA and DA* on Φ.
Main Methods:
- Utilized a mean-field potential model to define transition probabilities.
- Derived expressions for intrinsic and tracer diffusion coefficients.
- Analyzed the theoretical dependence on the thermodynamic factor Φ.
Main Results:
- The mean-field approach successfully reproduces the Darken equation.
- Intrinsic diffusivity (DA) was found to be independent of the thermodynamic factor (Φ).
- Tracer diffusivity (DA*) depends on the thermodynamic factor (Φ).
Conclusions:
- The mean-field model provides a more detailed understanding of diffusion coefficients than the Darken equation alone.
- Theoretical predictions align with experimental data from diffusion in metal alloys.
- This work clarifies the distinct roles of the thermodynamic factor in intrinsic and tracer diffusion.
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