Characterization of stoichiometric nanocrystalline spinel ferrites dispersed on porous silica aerogel

Casula, M.F. and Concas, G. and Congiu, F. and Corrias, A. and Loche, D. and Marras, C. and Spano, G. (2011) Characterization of stoichiometric nanocrystalline spinel ferrites dispersed on porous silica aerogel. Journal of Nanoscience and Nanotechnology, 11 (11). pp. 10136-10141. ISSN 1533-4880. (doi:https://doi.org/10.1166/jnn.2011.4975) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

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Official URL
http://dx.doi.org/10.1166/jnn.2011.4975

Abstract

Stoichiometric magnetic nanosized ferrites MFe 2O 4 (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 NiFe 2O 4 sample, highly blocked (?70%) in the MnFe 2O 4 sample and nearly fully blocked in the CoFe 2O 4 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 CoFe 2O 4 nanocrystals.

Item Type: Article
Uncontrolled keywords: Ferrimagnetics, Ferrites, Mössbauer Spectroscopy, Nanocrystalline Materials, Nanoscale Materials, Bulk value, Ferrimagnetics, Ferrite nanocrystals, Fitting procedure, Gain insight, Highly porous silica, Inversion degree, matrix, Mossbauer, Nano-scale materials, Nanocrystalline spinels, Nanocrystallines, Nanosized ferrite, Porous silica aerogel, Room temperature, Sol-gel procedure, Spherical nanocrystals, Ssbauer spectroscopies, Superparamagnetic relaxation, Superparamagnetics, Characterization, Ferrite, Ferrites, Manganese, Nanocrystals, Silica, Silica gel, Sol-gels, Superparamagnetism, Transmission electron microscopy, X ray diffraction, Gyrators
Subjects: Q Science > QC Physics > QC176.8.N35 Nanoscience, nanotechnology
Divisions: Faculties > Sciences > School of Physical Sciences > Functional Materials Group
Depositing User: Anna Corrias
Date Deposited: 16 Dec 2014 13:52 UTC
Last Modified: 04 Dec 2017 12:35 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/46165 (The current URI for this page, for reference purposes)
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