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Structural and Magnetic Characterization of Co and Ni Silicate Hydroxides in Bulk and in Nanostructures within Silica Aerogels

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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 CoFe2O4-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.

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Informasi Detail

Judul Seri

Chemistry of Materials

No. Panggil

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Penerbit

Washington, DC : American Chemical Society., 2009

Deskripsi Fisik

Chem. Mater. 2009, 21, 945–953

Bahasa

English

ISBN/ISSN

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Klasifikasi

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Tipe Isi

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Tipe Media

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Tipe Pembawa

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Edisi

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Subjek

KIMIA

Info Detail Spesifik

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Pernyataan Tanggungjawab

agus

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