X-ray absorption spectroscopic and magnetic characterization of cobalt-doped zinc oxide nanocrystals prepared by the molten-salt method |
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Authors: | Ah Reum Han Seong-Ju Hwang Yongnan Zhao Young-Uk Kwon |
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Affiliation: | 1. Center for Intelligent Nano-Bio Materials (CINBM), Division of Nano Sciences and Department of Chemistry, Ewha Womans University, Seoul 120-750, Republic of Korea;2. School of Materials Science and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300160, PR China;3. Department of Chemistry, BK-21 School of Chemical Materials Science, SKKU Advanced Institute of Nanotechnology, Sungkyunkwan University, Suwon, 440-746, Republic of Korea |
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Abstract: | The local atomic arrangement and electronic structure of the Co-doped Zn1−xCoxO nanocrystal have been quantitatively examined along with its magnetic properties. According to our analysis using powder X-ray diffraction, electron microscopy, and Zn K-edge X-ray absorption spectroscopy (XAS), phase-pure wurzite-structured Zn1−xCoxO nanocrystals have been successfully synthesized via the molten-salt method. The Co K-edge XAS analysis clearly demonstrates that all the Co2+ ions are substituted for the tetrahedral Zn sites of the Wurzite structure with a coordination number of 3.9 and a bond distance of 1.97 Å, ruling out the presence of magnetic impurity phase and Co-metal cluster. Magnetization measurements reveal that the present Zn1−xCoxO sample does not show any ferromagnetic transition down to 2 K. In this regard, we can conclude that Co-doped zinc oxide is not ferromagnetic but the previously reported ferromagnetism in this phase would be an extrinsic property. |
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Keywords: | 75.50.Pp 61.10.Ht 75.50.Tt |
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