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Scanning transmission electron microscopy study of the evolution of needle-like nanostructures in CoFe2O4 and nife 2O4 silica nanocomposite aerogels

Mountjoy, G., Loche, D., Wang, P., Sader, K., Corrias, A. (2011) Scanning transmission electron microscopy study of the evolution of needle-like nanostructures in CoFe2O4 and nife 2O4 silica nanocomposite aerogels. Journal of Physical Chemistry C, 115 (13). pp. 5358-5365. ISSN 19327447 (ISSN). (doi:10.1021/jp110472d) (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)

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. (Contact us about this Publication)
Official URL
https://doi.org/10.1021/jp110472d

Abstract

Magnetic nanocomposite materials consisting of 10 wt % CoFe 2O4 or NiFe2O4 nanoparticles in a silica aerogel matrix have been synthesized by the sol?gel method. A 100-kV aberration-corrected scanning transmission electron microscope (STEM) has been used to study these materials, and bright field and high angle annular dark field images show that after heat treatment at both 450 and 900 °C, they contain needle-like nanostructures Ì?1 nm in width and 10 nm in length. High resolution STEM images show that the needle-like nanostructures have a layered internal structure with typical interlayer spacings of 0.33 ± 0.02 nm. Electron energy loss spectroscopy using a 0.13-nm diameter probe gives information on the composition of these nanostructures. The results presented here for samples heat treated at 450 °C are consistent with needle-like nanostructures arising from Co and Ni silicate hydroxides which are separate from the also present Fe-containing phase of ferrihydrite nanoparticles. Samples heat treated at 900 °C have previously been shown to contain round ferrite nanoparticles ?8 nm in diameter. The results presented here are consistent with the needle-like nanostructures being transformed into ferrite-like phases after heat treatment at 900 °C, and the needle-like nanostructures are often found attached to round ferrite nanoparticles. © 2011 American Chemical Society.

Item Type: Article
DOI/Identification number: 10.1021/jp110472d
Additional information: Unmapped bibliographic data: LA - English [Field not mapped to EPrints] J2 - J. Phys. Chem. C [Field not mapped to EPrints] AD - Dipartimento di Scienze Chimiche and INSTM, Universita di Cagliari, S.P. Monserrato-Sestu Km 0.700, I-09042 Monserrato, Cagliari, Italy [Field not mapped to EPrints] AD - SuperSTEM, Daresbury Laboratory, Keckwick Lane, Daresbury, Cheshire, WA4 4AD, United Kingdom [Field not mapped to EPrints] AD - School of Physical Sciences, University of Kent, Canterbury,Kent, CT2 7NH, United Kingdom [Field not mapped to EPrints] AD - Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, United Kingdom [Field not mapped to EPrints] AD - Division of Physical Biochemistry, National Institutes for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, United Kingdom [Field not mapped to EPrints] DB - Scopus [Field not mapped to EPrints]
Uncontrolled keywords: After-heat treatment, Bright fields, Ferrihydrites, Ferrite nanoparticles, Gel method, High resolution, High-angle annular dark-field images, Interlayer spacings, Internal structure, Magnetic nanocomposites, matrix, Needle-like nanostructure, Scanning transmission electron microscopes, Scanning transmission electron microscopy, Silica aerogels, Silica nanocomposites, STEM images, Aerogels, Energy dissipation, Ferrite, Ferrites, Heat treatment, Nanocomposites, Nanoparticles, Needles, Silica, Silica gel, Silicates, Transmission electron microscopy, Electron energy loss spectroscopy
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: 17 Dec 2014 11:37 UTC
Last Modified: 29 May 2019 13:57 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/46205 (The current URI for this page, for reference purposes)
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