However, a significant portion of the differences in high-temperature processing observed under microwave versus conventional heating cannot be explained by the different heat deposition pattern. These so-called microwave effects include changes in the activation energy of diffusion,16 anisotropy of diffusion under heating in a linearly polarized microwave field,17 changes in the solid-state phase transformation temperatures,18 and many others. Apparently, these effects are of a more fundamental nature, associated with the microwave field energy conversion into other forms than equilibrium thermal motion—that is, with the so-called nonthermal effect of the electromagnetic field on materials.