Читать книгу Isotopic Constraints on Earth System Processes - Группа авторов - Страница 30

As mentioned in Section 1.2, the flux equation for a component i in a system that is inhomogeneous in both concentration and temperature can be represented by a pseudo‐binary equation

(1.8)

where is the effective binary diffusion coefficient of i in a mixture of components i and j, ρ is the density of the mixture, X_i and X_j are the mass fractions of i and j, and σ _i is the Soret coefficient. In a steady state J_i = 0 and the Soret coefficient becomes . Lesher and Walker (1986) determined Soret coefficients for the major components of silicate liquids using an approximate version of σ _i determined as , where is the average mass fraction of i in the starting composition of their experiments.