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Solid State Sciences, Volume 19, May 2013, Pages 156-161.
Takeshi Shiono, Fumiaki Tando, Hiromi Nakano, Yoshiyuki Sugahara
Department of Applied Chemistry, School of Advanced Science and Engineering, Waseda University, 3-4-1, Ohkubo, Shinjuku-ku, Tokyo 169-8555, Japan
Toyohashi University of Technology, Cooperative Research Facility Center, Hibariga-oka, Tempaku, Toyohashi, Aichi 441-8580, Japan
Kagami Memorial Laboratory for Materials Science and Technology, Waseda University, 2-8-26 Nishiwaseda, Shinjuku-ku, Tokyo 169-0051, Japan
Abstract
Microstructural behavior of {Gamma}-Fe2O3 formation in reactions between FeOCl and n-C5H11ONa was thoroughly investigated. Reactions were conducted at 50–150 °C for 3 days in an autoclave using n-C5H11OH as a solvent. X-ray diffraction (XRD) patterns and infrared (IR) spectra of the products suggested the crystallization of {Gamma}-Fe2O3 besides the formation of n-pentoxy derivatives of FeOCl. Scanning electron microscopic observation revealed that the FeOCl particles were divided into thin sheets upon reaction. The selected area electron diffractions (SAED) of the sheets revealed the crystallization of {Gamma}-Fe2O3 at even 80 °C, apparently due to the fact that the {Gamma}-Fe2O3 crystallization process involved a collapse from n-pentoxide derivatives with large separations between two adjacent layers. In the reaction at 150 °C, a part of the sheets was converted into highly oriented polycrystalline {Gamma}-Fe2O3 in improved crystallinity, and the SAED clearly showed that an oriented transformation with a crystallographic relationship of FeOCl (010)//{Gamma}-Fe2O3 (110) occurred. The reaction at 120 °C, on the contrary, led to the formation of randomly oriented {Gamma}-Fe2O3 crystallites within a sheet.
