Unusual Structural Relaxation for Rare-Earth Impurities in Sapphire:Ab InitioStudy of Lanthanum
| Autor: | Barrett G. Potter, M. P. Sears, Claudio Verdozzi, Dwight R. Jennison, Peter A. Schultz, J. C. Barbour |
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| Rok vydání: | 1998 |
| Předmět: | |
| Zdroj: | Physical Review Letters. 80:5615-5618 |
| ISSN: | 1079-7114 0031-9007 |
| DOI: | 10.1103/physrevlett.80.5615 |
| Popis: | A first-principles density-functional local density approximation study of substitutional La, using 120-atom supercells of $\ensuremath{\alpha}\ensuremath{-}\mathrm{Al}{}_{2}{\mathrm{O}}_{3}$, shows that La assumes a highly displaced position, moving over $0.5\AA{}$ from the original Al site. The La-O nearest neighbor distance is much smaller than the sum of standard $\mathrm{La}{}^{+3}$ and ${\mathrm{O}}^{\ensuremath{-}2}$ ionic radii. This is due to La being more ionic than in its own oxide, and to the role of the $5d\mathrm{shell}$, as the electron density within the displaced La is quite anisotropic. We discuss the implications for a systematic description of rare-earth ions implanted in sapphire. |
| Databáze: | OpenAIRE |
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