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Microstructure and Magnetic State of Fe3O4-SiO2 Colloidal Particles
Journal of Magnetics, Volume 20, Number 3, 30 Sep 2015, Pages 221-228
Abstract
Colloidal particles consisted of individual nanosized magnetite grains on the surface of the silica cores were obtained by two-stage sol-gel technique. Size distribution and microstructure of the particles were analyzed using atomic force microscopy, X-ray diffraction and Nitrogen thermal desorption. Magnetic properties of the particles were studied by the method of the longitudinal nonlinear response. It has been shown that nanoparticles of magnetite have a size corresponding to a superparamagnetic state but exhibit hysteresis properties. The phenomenon was explained using the magnetostatic interaction model based on the hypothesis of iron oxide particles cluster aggregation on the silica surface.
Keywords: magnetite; silica; colloidal particles; superparamagnetism; longitudinal nonlinear response; magnetostatic interaction
DOI: http://dx.doi.org/10.4283/JMAG.2015.20.3.221
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