The relaxation to flatness of sinusoidal single‐crystal nickel surfaces produced by a photoetching technique has been measured under high‐vacuum conditions. Results are presented on the variation of the surface diffusion coefficient Ds with temperature, orientation, and direction on certain low‐index planes. In the temperature range studied, the diffusion coefficient is found to vary only by a factor of about two for orientations close to (100), (111), and (110). For the (110) plane, Ds is anisotropic with Ds (110)[001]> Ds(110)[11̄0]. From surface relaxation measurements in the wavelength range where volume diffusion contributes significantly, the surface free energy has been determined for the (100) and (110) planes. The values are 1821±182 erg/cm2 and 1900±190 erg/cm2, respectively.

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