Diffusion in materials with variable temperature .1. One-dimensional problems

Solutions for diffusion in non-isothermal conditions are derived by analogy with diffusion in isothermal conditions when diffusivity is constant or time dependent. The effects of heating or cooling rates on the concentration profiles, boundary-layer thickness, and amount of material transferred, are described and can be assessed even when the temperature dependence of diffusivity and/or interfacial concentration is unknown. The effects of the rate of change in temperature on the amount of material transferred can be used also to assess whether this is controlled by diffusion or reaction.