Surface Self-Diffusion and Surface Energy of Nickel

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.