Adsorption,diffusion and self-diffusion on tungsten surfaces with adsorbed palladium |
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Authors: | H. Roux A. Piquet G. Pralong R. Uzan M. Drechsler |
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Affiliation: | Département de Physique des Matériaux, Associé au CNRS, Université Claude Bernard Lyon I, 43, boulevard du 11 Novembre 1918, 69621 Villeurbanne,France;Laboratoire des Mécanismes de la Croissance Cristalline, Centre du CNRS, Université d''Aix-Marseille III, 13397 Marseille, France |
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Abstract: | The influence of a Pd adsorption layer on the surface self-diffusion of tungsten has been measured using a field emitter technique. By adsorption of 1.2 × 1015 Pd atoms/cm2 — measured by high energy ion backscattering — the surface self-diffusion energy decreases from 70 to 54 kcal/mole, and the diffusivity from 0.95 to about 0.2 cm2/s, which corresponds to an increase of the diffusion coefficient by a factor 40 at 1600 K and 80 at 1400 K. Furthermore are determined (1) adsorption lifetimes in adsorption-desorption equilibria, (2) the isosteric adsorption heat (103 kcal/mole), and (3) the coefficient of Pd surface diffusion on W resulting in diffusion energies of 32 kcal/mole around (001) and 17 kcal/mole around (111). |
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