A parametric study on CoFe-based ferrite and alloy nanoparticle synthesis

Abstract

Magnetic nanoparticles (MNPs) have received great attention over the last two decades thanks to their potential uses in various application fields such as high-density recording media, magnetic separation and biomedicine. In this work we focus on the exploratory synthesis of cobalt ferrite and iron–cobalt NPs through thermal decomposition wet-chemical pathways. Several parameters were examined in order to elucidate their impact on the composition, morphology and magnetic behaviour of the produced nanomaterials. A range of metallic precursor types is first investigated, with a subsequent focus on the case of acetylacetonate salts. In addition, the reduction of CoFe₂O₄ to FeCo by employing a salt-matrix annealing stage is explored. Polyol and H₂-mediated methods are utilized to prepare FeCo alloy NPs in a direct manner. Multi-core nanostructures were also synthesized, and they are very promising for magnetic resonance imaging (MRI) and magnetic hyperthermia (MH) applications. The post-synthesis thermal treatment helped to convert ferrites to an iron–cobalt alloy, with the expense of significant particle size increase and aggregation. Alloy particles formed in a one-pot synthesis by polyol routes had a >100 nm size and hexagonal shape, while hydrogen-assisted reduction led to monodisperse ∼30 nm NPs with remarkable MH properties.