| Synthesis of an electromagnetic wave absorber for high-speed wireless communication. | |
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MedLine Citation:
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PMID: 19115851 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Millimeter waves (30-300 GHz) are starting to be used in next generation high-speed wireless communications. To avoid electromagnetic interference in this wireless communication, finding a suitable electromagnetic wave absorber in the millimeter wave range is an urgent matter. In this work, we prepared a high-performance millimeter wave absorber composed of a series of aluminum-substituted epsilon-iron oxide, epsilon-Al(x)Fe(2-x)O(3), nanomagnets (0 < or = x < or = 0.40) with a particle size between 25 and 50 nm. The materials in this series have an orthorhombic crystal structure in the Pna2(1) space group, which has four nonequivalent Fe sites and Al ion that predominantly occupies the tetrahedral [FeO(4)] site. The field-cooled magnetization curves showed that the T(C) values were 448, 480, and 500 K for x = 0.40, 0.21, and 0, respectively. The magnetization versus external magnetic field showed that the coercive field H(c) values at 300 K were 10.2, 14.9, and 22.5 kOe for x = 0.40, 0.21, and 0, respectively. The millimeter wave absorption properties were measured at room temperature by terahertz time domain spectroscopy. The frequencies of the absorption peaks for x = 0.40, 0.30, 0.21, 0.09, 0.06, and 0 were observed at 112, 125, 145, 162, 172, and 182 GHz, respectively. These absorptions are due to the natural resonance achieved by the large magnetic anisotropies in this series. Such frequencies are the highest ones for magnetic materials. Because aluminum is the third most abundant atom, aluminum-substituted epsilon-iron oxide is very economical, and thus these materials are advantageous for industrial applications. |
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Authors:
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Asuka Namai; Shunsuke Sakurai; Makoto Nakajima; Tohru Suemoto; Kazuyuki Matsumoto; Masahiro Goto; Shinya Sasaki; Shin-ichi Ohkoshi |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Journal of the American Chemical Society Volume: 131 ISSN: 1520-5126 ISO Abbreviation: J. Am. Chem. Soc. Publication Date: 2009 Jan |
Date Detail:
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Created Date: 2009-01-21 Completed Date: 2009-03-10 Revised Date: 2009-11-19 |
Medline Journal Info:
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Nlm Unique ID: 7503056 Medline TA: J Am Chem Soc Country: United States |
Other Details:
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Languages: eng Pagination: 1170-3 Citation Subset: IM |
Affiliation:
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Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adsorption Chemistry Techniques, Analytical / methods* Microscopy, Electron, Transmission Radiation* Temperature Time Factors X-Ray Diffraction |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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