Magnetic Properties of Co₃O₄ Nanoparticles Fabricated by Chemical Synthesis

摘要

Nanoparticles of cobalt oxide (CoO), of size 4.2 nm, were fabricated by heating Cobalt (Co) nanoparticles synthesized using dimethyl sulfoxide solvent. The temperature dependence of magnetization for field cool and zero field cool processes of CoO nanoparticles shows the bifurcation at 44 K. A cusp is observed at 1 T and higher applied fields indicating antiferromagnetic behavior in the system with the Néel temperature ( K. The estimated magnetic entropy change () for the CoO nanoparticles suggests the unusual behavior in magnetic phase transformation of the CoO nanoparticles. A normal magnetocaloric effect (MCE) at K and inverse MCE at K are observed. These results correlate the magnetocaloric properties to the magnetic phase transitions in the CoO nanoparticle system.