Magnetic properties of cobalt-ferrite nanoparticles embedded in polystyrene resin
2006; American Institute of Physics; Volume: 99; Issue: 8 Linguagem: Inglês
10.1063/1.2165922
ISSN1520-8850
AutoresP. P. Vaishnava, U. Senaratne, E. C. Buc, R. Naik, V. M. Naik, G. M. Tsoĭ, L. E. Wenger, P. Boolchand,
Tópico(s)Magnetic properties of thin films
ResumoSamples of maghemite and cobalt-ferrite nanoparticles (sizes, 3–10nm) were prepared by cross-linking sulfonated polystyrene resin with aqueous solutions of (1) FeCl2, (2) 80%FeCl2+20%CoCl2, (3) FeCl3, and (4) 80%FeCl3+20%CoCl2 by volume. Chemical analysis, x-ray powder-diffraction, and Fe57 Mössbauer spectroscopic measurements show that samples 1 and 3 consist of γ-Fe2O3 nanoparticles (sizes, ∼10 and 3nm) and sample 2 and 4 consist of CoxFe3−xO4 nanoparticles (sizes, ∼10 and 4nm). The temperature dependence of the zero-field-cooled and field-cooled magnetizations at low temperatures, together with a magnetic hysteresis in the M versus H data below blocking temperatures, demonstrate superparamagnetic behavior. The introduction of Co in the iron oxide-resin matrix results in an increase in the blocking temperature of nanoparticles.
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