Characterization of Stoichiometric Nanocrystalline Spinel Ferrites Dispersed on Porous Silica Aerogel

Authors: Casula, M. F.; Concas, G.; Congiu, F.; Corrias, A.; Loche, D.; Marras, C.; Spano, G.

Source: Journal of Nanoscience and Nanotechnology, Volume 11, Number 11, November 2011 , pp. 10136-10141(6)

Publisher: American Scientific Publishers

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Abstract:

Stoichiometric magnetic nanosized ferrites MFe2O4 (M = Mn, Co, Ni) were prepared in form of nearly spherical nanocrystals supported on a highly porous silica aerogel matrix, by a sol–gel procedure. X-ray diffraction and transmission electron microscopy indicate that these materials are made out of non-agglomerated ferrite nanocrystals having size in the 5-10 nm range. Investigation by Mössbauer Spectroscopy was used to gain insights on the superparamagnetic relaxation and on the inversion degree. Magnetic ordering at room temperature varies from superparamagnetic in the NiFe2O4 sample, highly blocked (∼70%) in the MnFe2O4 sample and nearly fully blocked in the CoFe2O4 sample. A fitting procedure of the Mössbauer data has been used in order to resolve the spectrum into the tetrahedral and octahedral components; in this way, an inversion degree of 0.68 (very close to bulk values) was obtained for 6 nm silica-supported CoFe2O4 nanocrystals.

Keywords: FERRIMAGNETICS; FERRITES; MOSSBAUER SPECTROSCOPY; NANOCRYSTALLINE MATERIALS; NANOSCALE MATERIALS

Document Type: Research Article

DOI: http://dx.doi.org/10.1166/jnn.2011.4975

Publication date: November 1, 2011

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  • Journal for Nanoscience and Nanotechnology (JNN) is an international and multidisciplinary peer-reviewed journal with a wide-ranging coverage, consolidating research activities in all areas of nanoscience and nanotechnology into a single and unique reference source. JNN is the first cross-disciplinary journal to publish original full research articles, rapid communications of important new scientific and technological findings, timely state-of-the-art reviews with author's photo and short biography, and current research news encompassing the fundamental and applied research in all disciplines of science, engineering and medicine.
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