Temperature Dependence of the Diffusional Peclet Number in Sublimation of Some Simple Substances

We consider sublimation in M–X (M = Mg, Cr, Sm, Eu; X = impurity with a preset activation energy for diffusion) model systems, for which the Peclet number Ре = wr/(ρD) (where D is the diffusion coefficient, w is the mass vaporization rate, ρ is the density of the substance, and r is a size factor) is calculated as a function of temperature by a semiempirical method. The Pe(T) temperature dependence is shown to exhibit complex behavior. Knowledge of the Peclet number as a function of temperature allows one to use it for calculating sublimation refining of a substance in the case of an impurity with a given separation factor and get an idea of how the sublimation refining process depends on temperature.