A comprehensive study of Co1−xNixFe2O4 nanoparticles fabricated via three different synthetic methods

Abstract

Wereport on three different synthetic methods for producing Co1−xNixFe2O4 nanoparticles (x=0.0, 0.4, and 1.0): combustion (C), hydrothermal (HT), and forced hydrolysis (FH). Theoretical fittings of the ferromagnetic resonance (FMR) lines were achieved by considering a proposed four-fold symmetry model for randomly dispersed magnetic nanoparticles (NPs). The average grain size (D), between 10 and 80 nm, and magnetic properties are found to depend strongly on both the selectedsynthesis route and stoichiometry (x). Interestingly, while the HT- and FH-methods provide NPs with no systematic dependence of coercive field and remanence, upon x or D, the C-method showedmonotonic dependence. The magnetocrystalline anisotropy field (Ha), extracted from simulating theFMRspectra, systematically reduces with increasing x, regardless the synthetic route used. Worth mentioning that the largest (smallest) variation inHa is observed for the C-method (HTmethod) equals toΔHa=−3853 Oe (ΔHa=−1676 Oe).