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A technique is presented to calculate grain-boundary widths and grain-boundary diffusion coefficients in metals and nonmetals using grain growth, sintering, diffusion and/or creep data. High-purity metals yield boundary widths of the order of a few atomic diameters, whereas ionic materials yield ``effective boundary widths'' orders-of-magnitude wider.

model proposed here suggests that the grain size should be an , < overestimate if the surface is assumed to be basically flat and contoured only by grain boundary grooves. An equilibrium surface, such as might be formed by polishing and thermal etching of a material in which the surface energy is isotropic, is shown in Fig. 2. The amplitude of the modulations in the surface contour is:

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