Ordered Mesoporous Fe2O3 with Crystalline Walls

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• 作者：Feng Jiao ; Andrew Harrison ; Jean-Claude Jumas ; Alan V. Chadwick ; Winfried Kockelmann ; and Peter G. Bruce
• 刊名：Journal of the American Chemical Society
• 出版年：2006
• 出版时间：April 26, 2006
• 年：2006
• 卷：128
• 期：16
• 页码：5468 - 5474
• 全文大小：431K
• 年卷期：v.128,no.16(April 26, 2006)
• ISSN：1520-5126

文摘

-Fe₂O₃ has been synthesized with an ordered mesoporous structure and crystalline walls thatexhibit a near-single crystal-like order. The unique magnetic behavior of the material, distinct from bulknanoparticles of -Fe₂O₃ or mesoporous Fe₂O₃ with disordered walls, has been established. Magneticsusceptibility, Mössbauer, and neutron diffraction data show that the material possesses the same long-range magnetic order as bulk -Fe₂O₃, despite the wall thickness being less than the 8 nm limit belowwhich magnetic ordering breaks down in nanoparticulate -Fe₂O₃, yet the Morin transition of bulk -Fe₂O₃is absent. It is also shown by TEM, PXRD, and EXAFS that -Fe₂O₃ with the same ordered mesoporousstructure but disordered walls contains small crystalline domains. Mössbauer and magnetic susceptibilitydata demonstrate that this material exhibits no long-range magnetic order but superparamagnetic behavior.