Abstract
High angular resolution electron channeling x-ray spectroscopy (HARECXS) was examined as a practical tool to locate lattice-ions in spinel crystals. The orientation dependent intensity distribution of emitted x-rays obtained by HARECXS is so sensitive to lattice-ion configuration in the illuminated areas that the occupation probabilities on specific positions in the crystal lattice can be determined accurately through comparison with the theoretical rocking curves. HARECXS measurements have revealed partially disordered cation arrangement in MgO·nAl2O3 with n=1.0 and 2.4. Most Al3+ lattice-ions occupy the octahedral (VI) sites with 6-fold coordination, while Mg2+ lattice-ions reside on both the tetrahedral (IV) and the octahedral (VI) sites. The structural vacancies are enriched in the IV-sites. Further evacuation of cations from the IV-sites to the VI-sites is recognized in a disordering process induced by irradiation with 1 MeV Ne+ ions up to 8.9 dpa at 870 K.
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T. Soeda, PhD Thesis Research, in progress, Kyushu University.
Acknowledgments
The authors should like to express their gratitude to Dr. Lynn Rehn for arrangements for this collaborative work of the two groups at KU and ANL. They are also indebted to Dr. C. J. Rossouw at CSIRO for his kind offer of the efficient calculation program and invaluable comments. This research was partly supported by the US Department of Energy under contract BES-MS W-31-109-Eng-38 and by the Grant-in-Aid for scientific research from the Ministry of Education, Science, Culture and Sports, Japan and from the Japan Society of Promotion of Science.
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Matsumura, S., Soeda, T., Zaluzec, N.J. et al. Electron Channeling X-Ray Microanalysis for Cation Configuration in Irradiated Magnesium Aluminate Spinel. MRS Online Proceedings Library 589, 129 (1999). https://doi.org/10.1557/PROC-589-129
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DOI: https://doi.org/10.1557/PROC-589-129