X-ray absorption fine-structure study on the fine structure of lutetium segregated at grain boundaries in fine-grained polycrystalline alumina |
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| Authors: | Hidehiro Yoshida Yuichi Ikuhara Taketo Sakuma Masaki Sakurai Eiichiro Matsubara |
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| Institution: | 1. Department of Advanced Materials Science , Graduate School of Frontier Science, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan;2. Engineering Research Institute , School of Engineering, The University of Tokyo , 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656, Japan;3. Institute for Materials Research , Tohoku University , 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan |
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| Abstract: | Local atomic structures around the Lu3+ ion in a 0.1?mol%?LuO1.5-doped fine-grained Al2O3, in which the doped Lu3+ ions segregate to the grain boundaries, was characterized by Lu L3-edge X-ray absorption fine structure. Structural parameters in LuO1.5-doped Al2O3 were determined by a curve-fitting method, and the results showed that six O2? ions coordinate with the Lu ion in LuO1.5-doped Al2O3. In addition, it was also revealed that the Lu–O interatomic distance in Lu-doped Al2O3 was close to that in Lu2O3, which was about 19% longer than the Al–O interatomic distance in undoped Al2O3. The present results indicated that the local atomic structures around Lu in Al2O3 are close to that in Lu2O3. It is thus supposed that atomic distances between Al3+ and O2? ions in the vicinity of Lu-segregated grain boundaries are shortened in comparison with that in undoped Al2O3. A first-principles molecular orbital calculation was performed for the Al2O9]?12 model cluster, and the shortening of the Al–O interatomic distance was found to have an effect of increasing the ionicity in Al3+ ions. |
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