Fabrication, structure and magnetic properties of CoPt3, CoPt and Co3Pt nanoparticles

Abstract A set of Co x Pt 100− x nanoparticles (NPs) was synthesized by the sol–gel method. The structure and magnetic properties of the produced samples were investigated by x-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and a vibrating sample magnetometer. When the Co content ranged from 25 to 75 at%, the results of XRD, HRTEM and SAED revealed the formation of L1 2 CoPt 3 , L1 0 CoPt and face-centred cubic Co 3 Pt NPs. Magnetic measurements indicated that CoPt 3 and Co 3 Pt had soft magnetic properties. When the Co composition was 50 at%, the sample coercivity reached a giant value of ∼470 kA m −1 .