Effect of boron addition on the phase-transition temperature of CoPt-B nanoparticles synthesized by sol-gel autocombustion using sago starch as a chelating agent

In this research, we reported the effect of boron addition on the phase-transition temperature of CoPt-B nanoparticles using a sol-gel autocombustion method. Sago starch was used as a chelating agent. From the results, the suitable values of the sago starch concentration, boron concentration, and annealing temperature were determined to be 10% (w/v), 0.20 mol/L, and 500 degrees C, respectively. All the synthesized samples were characterized by the SEM, TEM, EDS, XRD, and VSM techniques. The XRD patterns of the synthesized CoPt-B nanoparticles demonstrated that the phase-transition temperature of CoPt-B changes from the disordered A1 phase to the ordered L1(0)phase at 500 degrees C. It can be concluded that the addition of boron could reduce about 100 degrees C of the ordering temperature of CoPt-B. Moreover, the VSM data confirmed that the obtained samples exhibited their ferromagnetism properties, indicating that the synthesized CoPt-B nanoparticles can be applied as ultrahigh-density magnetic recording media.