Diffusion parameters of B in Cu determined by β-radiation-detected NMR
| Autor: | H. Ackermann, F. Kroll, Hans-Jürgen Stöckmann, M. Füllgrabe, D. Peters, B. Ittermann |
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| Rok vydání: | 2001 |
| Předmět: | |
| Zdroj: | Physical Review B. 64 |
| ISSN: | 1095-3795 0163-1829 |
| DOI: | 10.1103/physrevb.64.224302 |
| Popis: | Using \ensuremath{\beta}-radiation-detected nuclear magnetic resonance (\ensuremath{\beta}-NMR) in the special form of cross-relaxation spectroscopy we studied the diffusional behavior of implanted ${}^{12}\mathrm{B}$ nuclei in Cu single crystals at temperatures $T=115--750\mathrm{K}.$ An extended and completely revised dynamic theory of nuclear cross relaxation is developed to analyze the experimental data. Especially the incorporation of (hitherto neglected) spin-lattice relaxation effects turned out to be an important improvement. Applying this formalism we obtain activation energies of ${E}_{a}=0.57(5)\mathrm{eV}$ for the migration of interstitial B, the dominating fraction for $T\ensuremath{\lesssim}400\mathrm{K},$ and of ${E}_{a}=1.15(10)\mathrm{eV}$ for substitutional B formed at higher temperatures. The previously found direct-exchange mechanism for the diffusion of substitutional B in Cu is confirmed by our analysis. |
| Databáze: | OpenAIRE |
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