Structure and magnetic properties of granular NiZn-ferrite - SiO2

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.

Bibliographic Details

Main Authors:	Albuquerque,Adriana Silva de, Ardisson,José Domingos, Bittencourt,Edison, Macedo,Waldemar Augusto de Almeida
Format:	Digital revista
Language:	English
Published:	ABM, ABC, ABPol 1999
Online Access:	http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14391999000300021
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