Magnetic properties of CoxPt100−x nanoparticles

CoxPt100−x nanoparticles (x = 50, 59, and 73) were prepared by the chemical reduction of Cobalt (II) chloride and Chloroplatinic acid, then ultrasonicated for 2 h. After annealing at various temperatures from 450 °C to 700 °C for 1 h, structure change was observed and samples show hard magnetic properties which depend strongly on chemical composition and annealing temperature. The highest coercivity value of 1.15 kOe was obtained at room temperature for sample with x = 50 annealed at 500 °C. Chemical reduction combined with ultrasound is a useful method to prepare CoPt nanoparticles.