Vacancy wind

M0 is a numerical factor that is specific for the crystal structure. The second term in brackets stems from what is called the vacancy wind effect. We note that D for AO-BO (oxide) interdiffusion under the condition d i0 = 0 is analogous to D for A-B (alloy) interdiffusion when djuv = 0 and vacancy equilibrium prevails throughout the alloy. 

Finally, it should be mentioned that the calculation of correlation effects for crystals in which fluxes occur as the result of chemical potential gradients yields extra terms not yet pointed out because of the spatial inhomogeneity of defects. This higher approximation has been calculated for the case of a vacancy diffusion coefficient, and is known as a result of the vacancy wind . It can be neglected in first order calculations [5]. 

All fluxes are written down in the lattice reference frame, Db, Dg, Dv are, respectively, the partial diffusivity of B, the tracer diffusivity of B, and the diffusivity of vacancies inside the nanoshell. In Equations 7.23 and 7.24, we have neglected Manningfs corrections (vacancy wind effect). It could be done but it would make the mathematical equations more cumbersome without a substantial change in the main results. Under the same assumption, the mentioned diffusivities are interrelated in the following way... 

Note that we use the fluxes in the lattice reference frame and intrinsic diffusivities (instead of interdiffusivity) according to our basic approximation of no Kirkendall shift. We neglect the correlation factors of Manning s vacancy wind terms [28] since they can change results only quantitatively. Both tracer diffusivities are proportional to vacancy concentration. Here we use one more approximation that we treat only one effective vacancy concentration, without distinguishing between sublattices in the compound. We take... 

Here Manning s corrections due to the effect of vacancy wind are neglected. Our preliminary estimates have shown that these corrections, at least for a disordered solution, do not change the general picture. In this approximation... 

Let us modify the scheme described in the previous paragraph for the case of phase formation at a direct current imposed onto the diffusion zone, from A to B or in the reverse direction (the pattern of phase formation at direct current is reviewed in detail in Chapters, alternative approach discussed in [19]). Current-induced electron wind results in drift components in component and vacancy fluxes described by... 

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