Structural and magnetic characterization of Co and Ni silicate hydroxides in bulk and in nanostructures within silica aerogels

Carta, D., Casula, M.F., Corrias, A., Falqui, A., Loche, D., Mountjoy, G., Wang, P. (2009) Structural and magnetic characterization of Co and Ni silicate hydroxides in bulk and in nanostructures within silica aerogels. Chemistry of Materials, 21 (5). pp. 945-953. ISSN 0897-4756. (doi:10.1021/cm8029714) (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/10.1021/cm8029714

Abstract

X-ray diffraction, transmission electron microscopy, X-ray absorption spectroscopy, and magnetic measurements were used to investigate highly porous silica aerogels containing iron and cobalt or iron and nickel, calcined at 450 °C, which are intermediates in the formation of CoFe2O 4-SiO2 and NiFe2O4-SiO2 aerogel nanocomposites. Aerogels without iron and pure Co and Ni silicate hydroxides were also studied. The aerogel samples containing iron and cobalt or iron and nickel present two separate phases, one containing iron in the form of ferrihydrite and the other either Co or Ni silicate hydroxides. The silicate hydroxides are present in the aerogels in form of nanoparticles with a one-dimensional appearance in electron microscopy images, which are therefore anisotropic nanostructures, such as nanoneedles or nanosheets. The study of the magnetic properties indicates that the coercivity is greatly modified by size and shape of the particles going from pure Co or Ni silicate hydroxides to the aerogel samples containing only nickel or only cobalt. Finally, in the samples also containing iron, the total magnetic behavior is influenced both by the presence of ferrihydrite and by the possible diffusion of iron in the nanostructures of cobalt or nickel silicate hydroxide.

Item Type: Article
DOI/Identification number: 10.1021/cm8029714
Uncontrolled keywords: Aerogel nanocomposites, Anisotropic nanostructures, Coercivity, Diffusion of irons, Electron microscopy images, Ferrihydrite, Highly porous silicas, Magnetic behaviors, Magnetic characterizations, Magnetic measurements, Nickel silicates, One-dimensional, Silica aerogels, Size and shapes, X- ray diffractions, X-ray absorption spectroscopies, Absorption spectroscopy, Aerogels, Calcination, Ceramic materials, Cobalt, Magnetic properties, Nanoneedles, Nanosheets, Nickel alloys, Silica, Silica gel, Silicates, Transmission electron microscopy, X ray spectroscopy, Nickel
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 11:53 UTC
Last Modified: 29 May 2019 13:57 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/46215 (The current URI for this page, for reference purposes)
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