An analytical solution was presented, for non steady-state diffusion in coated materials, which assumed the existence of a constant gradient in the coating. Possible surface and interface effects were taken into account to the extent of satisfying boundary conditions of the first kind. The solution was generally applicable to thin films in which the diffusion equation was obeyed. The solution provided an easy means for studying diffusion processes in multi-layered materials.

A.Mezin, J.Lepage, P.B.Abel: Thin Solid Films, 1996, 272[1], 124-31