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Title: High-frequency millimeter wave absorption of indium-substituted ε-Fe{sub 2}O{sub 3} spherical nanoparticles (invited)

In this work, we prepared indium-substituted ε-iron oxide (ε-In{sub x}Fe{sub 2−x}O{sub 3}) spherical nanoparticles by a combination method of reverse-micelle and sol-gel techniques. The powder X-ray diffraction pattern with Rietveld analysis shows that ε-In{sub x}Fe{sub 2−x}O{sub 3} has an orthorhombic crystal structure (space group: Pna2{sub 1}), and the In{sup 3+} ions mainly replace the Fe{sup 3+} ions at B site among the four nonequivalent Fe{sup 3+} sites (A–D sites). The magnetic measurements show that the coercive field (H{sub c}) at 300 K decreases with increasing x, i.e., H{sub c} = 21.9 kOe (x = 0), 12.2 kOe (x = 0.04), 11.6 kOe (x = 0.09), 7.8 kOe (x = 0.13), and 5.9 kOe (x = 0.18). Millimeter wave absorption was measured by terahertz time-domain spectroscopy, and the decrease of resonance frequency (f{sub r}) is observed, i.e., f{sub r} = 182 GHz (x = 0), 160 GHz (x = 0.04), 143 GHz (x = 0.09), 123 GHz (x = 0.13), and 110 GHz (x = 0.18). This decrease in the f{sub r} value is understood by the decrease of magnetic anisotropy, which is caused by the replacement of Fe{sup 3+} (S = 5/2) with nonmagnetic In{sup 3+} (S = 0) at B site contributing to the magnetic anisotropy.
Authors:
;  [1] ;  [2] ; ;  [3] ;  [1] ;  [4]
  1. Department of Chemistry, School of Science, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)
  2. Department of Physics, Chiba University 1-33 Yayoicho, Inage Ward, Chiba-shi, Chiba 263-8522 (Japan)
  3. Institute for Solid State Physics, The University of Tokyo 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan)
  4. (Japan)
Publication Date:
OSTI Identifier:
22273588
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 17; Conference: 55. annual conference on magnetism and magnetic materials, Atlanta, GA (United States), 14-18 Nov 2010; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ABSORPTION; ABSORPTION SPECTROSCOPY; ANISOTROPY; GHZ RANGE; INDIUM COMPOUNDS; INDIUM IONS; IRON IONS; IRON OXIDES; NANOSTRUCTURES; ORTHORHOMBIC LATTICES; PARTICLES; POWDERS; SOL-GEL PROCESS; X-RAY DIFFRACTION