Synthesis of cobalt nanoparticles from [bis(2-hydroxyacetophenato)cobalt(II)] by thermal decomposition

Abstract

[Bis(2-hydroxyacetophenato)cobalt(II)] was used as a new precursor to prepare cobalt (Co) and tricobalt tetraoxide (Co 3O 4) nanoparticles of 15–25 nm in average diameter by thermal decomposition. The different combinations of triphenylphosphine, and oleylamine were added as surfactants to control the particle size. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and Fourier transform infrared (FT-IR) spectroscopy. Time-dependent FT-IR studies indicate that oxidation of the as-synthesized cobalt nanoparticles in air is slow. The valence change of cobalt from the nanoparticle sample is not observed after it is kept in hexane under air for 30 days. The magnetic property was studied with vibrating sample magnetometer (VSM). The hysteresis loops of the obtained samples reveal the soft magnet behaviors the enhanced coercivity ( H c ) and decreased saturation magnetization ( M s ) in contrast to their respective bulk materials.