Transport of solid through the gas phase using a single heterogeneous equilibrium

A model is developed for one-dimensional steady-state diffusion-limited transport of solid between source and seed planes in the presence of a known chemical equilibrium. The transport depends on the reaction enthalpy, the separation and temperature difference between source and seed, and the departure from equilibrium at the crystal surfaces. A simple expression gives the dependence of transport on the gaseous binary diffusion coefficients, the reaction coefficients, and mean partial pressures of the various species present.