Injection of self-interstitials into a single crystal of nickel: One-interstitial vs. two-interstitial model

Abstract

"In case the reader is not aware of it, it should be pointed out that there is, and has been, a long-standing controversy on the interpretation of the recovery stages in fcc metals. I suspect that after this conference there will still be a controversy!" Twenty years after these prophetic words were spoken by J.W. Corbett [i], Frank and Seeger [2] addressed the configuration of a cubic lattice defect in Ni that was discovered in a DPAC measurement on ~11In [3]. They argue that the defect must be a mixed interstitial, contrary to the original interpretation according to which the defect consists of an 111In atom at the centre of a tetrahedron of four nearest-neighbour vacancies. They further argue that, since the defect is formed in recovery stage III, its structure is a sensitive test of the existing defect models: the one-interstitial model according to which recovery stage III is associated with vacancy migration, and the two-interstitial model which denies any vacancy mobility in recovery stage III. In the following we report on the annihilation of C-defects by self-interstitial injection. We prepared a single crystal of Ni so that about 30% of the implanted *11In atoms were associated with the cubic defect, and bombarded it subsequently with i00 eV Xe ions to stepwise increasing doses ranging from 1.10'5-1.1017 cm -2. The Xe ions transfer at most 3.7 times the displacement energy to the host lattice atoms, and eventually initiate a displacement collision sequence leaving a vacancy at the surface. The self-interstitials injected in this way into the Ni lattice will move on