Structural and magnetic characterization of aerogel-produced Ge sub(0.5)Fe sub(2.5)O sub(y) nanoparticles

Fine powders of Ge sub(0.5)Fe sub(2.5)O sub(y) with nearly uniform grain size were synthesized through the sol-gel supercritical drying technique, and were characterized by XRD, TEM, SQUID, and Mossbauer spectroscopy. Each grain is comprised of a spinel-crystallite core of mean size 11.2 nm and a th...

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Bibliographic Details
Published in:Journal of magnetism and magnetic materials 2000-01, Vol.212 (1), p.112-120
Main Authors: Hamdeh, H H, Barghout, K, Ho, J C, Willey, R J, O'Shea, M J, Chaudhuri, J
Format: Article
Language:English
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Summary:Fine powders of Ge sub(0.5)Fe sub(2.5)O sub(y) with nearly uniform grain size were synthesized through the sol-gel supercritical drying technique, and were characterized by XRD, TEM, SQUID, and Mossbauer spectroscopy. Each grain is comprised of a spinel-crystallite core of mean size 11.2 nm and a thin amorphous shell. Such a complex structure yields collinear ferrimagnetism in the core and canted ferrimagnetism with multiple configurations in the shell. At low temperatures, the low-field dependence of magnetization as it approaches saturation suggests the presence of a weak random anisotropy, and the high-field dependence suggests an increase in the magnetic moments of molecules. Both tetrahedral and octahedral sites are occupied by Ge super(4+) and Fe, mainly trivalent, cations. The charge balance is presumably provided by cation and/or anion vacancies.
ISSN:0304-8853