The analysis of dislocation pipe radius for diffusion.

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Dislocation pipe radius for diffusion and the distribution are analyzed using combined an equivalent boundary slab model and a dislocation pipe model. Both models were applied to oxygen self-diffusion in MgO single crystal. The lattice diffusion coefficient Dl and the diffusion coefficient for oxygen diffusion along a dislocation, Dd, at 1350°C are obtained as Dl=1.17×10−20 and Dd=4.44×10−16 m2sec−1, respectively. Oxygen diffusion along the dislocation takes place within a pipe of radius 0.18 nm surrounding the dislocation. The theoretical results of dislocation structures, dislocation density d=3.2×1014 m−2 and subgrain size b=1.15 mum, are found to agree well with the electron-microscopic experiments by Moriyoshi and Ikegami (1985).