Effect of samarium addition on structural and magnetic properties of polyol-synthesized CoxC/Co nanocomposites

Cobalt and cobalt carbides play an essential role in enhancing the magnetic properties, hardness, and durability of advanced magnetic materials. These desirable characteristics originate from their high magnetic moment, favorable Curie temperature, and structural stability. In this study, Co x C/Co nanocomposite powders containing different amounts of samarium were synthesized using the polyol method. The influence of samarium content on the structural and magnetic properties of the nanopowders was systematically investigated. The synthesized powders were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), and first-order reversal curve (FORC) measurements. The XRD analysis indicated that samarium addition facilitated the formation of the metallic cobalt phase. The crystallite size was calculated using the Scherrer method, with the phase percentages determined by the Rietveld method. Increasing the samarium content from 1 to 3 wt.% resulted in an increase in the crystallite size from 19 to 27 nm and an increase in the metallic cobalt fraction from 11 to 26 wt.%. These results suggest that samarium may play a kinetic modifier role in promoting metallic cobalt formation during the polyol process. The microscopic observations were in good agreement with the XRD findings. The magnetic measurements further confirmed that the saturation magnetization increased markedly from 94 to 144 emu/g as the samarium content increased from 1 to 3 wt.%.