Abatmct-We have studied the role of oxygen in grain boundary (gb.) and bulk diffusion of silver between 450" and tWO"C. The role of this solute, in the bulk as in the grain boundary is not affected by the initial purity of samples character&t by residual resistivity ratio of 300 and 1800. Oxygen enhances silver bulk diffusion over the range of temperature we have studied: this effect is explained by a strong oxygen-vacancy interaction which decreases both the formation and migration energies of vacancies. The diffusion parameters of the pairs "oxygen-vacancy" have been calculated. The g.b. diffusion is unaffected by oxygen and metallic residual impurities. This result may suggest that an enhancement of the nominal purity does not necessarily have an effect on g.b. chemical composition, or that silver diffusion occurs on sites forbidden to oxygen with a small binding energy between oxygen and vacancy linked to the relaxed structure of the g.b.
R&amn&-Nous avons &die l'inf&nce de l'oxygine sur la diffusion volumique et inter~ul~~ de Pargent et&e 450 et 800Β°C. Cette itdhtence est ind~dante de la punt6 initiale des ~~tii~ns (c.am&ris&s par des rapports de r&ativiti compris entre 300 et 1800). L'oxyg&te a&l&e la diffusion vohtmique de l'argent $ toute temperature: ce r&hat est interpr&e par une forte interaction lacunboxyg&ne qui diminue simulta&ment les energies de formation et de migration des lacunes. Les parametres de diffusion des paires "lacune+oxyg&ne" ont pu &c &ah&. L'oxyg&e n'influmcc pas la diffusion intergranulairc de I'argent. Cc r&hat peut indiquer que Is put& nominale ne rend pas compte de la composition chimique des joints; il peut cependant i?tre aussi explique par une diminution des interactions oxyg&ne-lacune dam le joint (structure relax&e) a condition d'afl'ecter 4 l'argent et l'oxyg&ne des sites intergranulaires dil%ents.