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Type: Artigo de periódico
Title: Synthesis Of Granular Fe-al2o3 By The Sol-gel Method
Author: Santos A.
Ardisson J.D.
Tambourgi E.B.
Macedo W.A.A.
Abstract: We have investigated the structural and magnetic properties of a granular composite of iron particles dispersed in alumina matrix, obtained starting from an aqueous solution containing Al(NO3)3·9H2O and FeSO4·7H2O. The samples were characterized by X-ray diffraction and fluorescence, Mössbauer spectroscopy (MS) and vibrating sample magnetometry (VSM). Samples with 7.8 wt% Fe were submitted to two different heat treatments with the aim of reducing the iron oxides into metallic iron. Series A was submitted to calcination between 100°C and 1200°C, followed by reduction in ultra pure H2 at 600°C during 2 h; Series B was submitted to reduction at 600°C or at 1000°C directly after drying at 80°C. As determined by MS, we have obtained a maximum of 24% metallic Fe in series A and of 74% α-Fe in series B, after reduction at 1000°C. By VSM, at 300 K, the maximum coercivity of 819 Oe was obtained for the samples calcinated at 800°C before reduction and an almost constant saturation magnetization of 2 emu/g. In series B, samples with 74% α-Fe presented a coercivity of 370 Oe and a saturation magnetization of 9.0 emu/g. The applied synthesis method seems to be an interesting alternative way to obtain magnetic Fe nanoparticles in a non-magnetic alumina matrix. © 1998 Elsevier Science B.V. All rights reserved.
Rights: fechado
Identifier DOI: 
Date Issue: 1998
Appears in Collections:Unicamp - Artigos e Outros Documentos

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