Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/34578
Type: Artigo de periódico
Title: Structure and magnetic properties of granular NiZn-ferrite - SiO2
Author: Albuquerque, Adriana Silva de
Ardisson, José Domingos
Bittencourt, Edison
Macedo, Waldemar Augusto de Almeida
Abstract: Granular systems composed by nanostructured magnetic materials embedded in a non-magnetic matrix present unique physical properties that depend crucially on their nanostructure. In this work, we have studied the structural and magnetic properties of NiZn-ferrite nanoparticles embedded in SiO2, a granular system synthesized by sol-gel processing. Samples with ferrite volumetric fraction x ranging from 6% to 78% were prepared, and characterized by X-ray diffraction, Mössbauer spectroscopy and vibrating sample magnetometry. Our results show the formation of pure stoichiometric NiZn-ferrite in the SiO2 matrix for x < 34%. Above these fraction, our samples presented also small amounts of Fe2O3. Mössbauer spectroscopy revealed the superparamagnetic behaviour of the ferrimagnetic NiZn-ferrite nanoparticles. The combination of different ferrite concentration and heat treatments allowed the obtaintion of samples with saturation magnetization between 1.3 and 68 emu/g and coercivity ranging from 0 to 123 Oe, value which is two orders of magnitude higher than the coercivity of bulk NiZn-ferrite.
Subject: granular materials
nanostructures
NiZn-ferrite - SiO2
superparamagnetism
Editor: ABM, ABC, ABPol
Rights: aberto
Identifier DOI: 10.1590/S1516-14391999000300021
Address: http://dx.doi.org/10.1590/S1516-14391999000300021
http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14391999000300021
Date Issue: 1-Jul-1999
Appears in Collections:Unicamp - Artigos e Outros Documentos

Files in This Item:
File Description SizeFormat 
S1516-14391999000300021.pdf309.43 kBAdobe PDFView/Open


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.