Influence of Cu on the Improvement of Magnetic Properties and Structure of L1(0) FePt Nanoparticles

L1(0) ordered FePt and FePtCu nanoparticles (NPs) with a good dispersion were successfully fabricated by a simple, green, one-step solid-phase reduction method. Fe (acac)(3), Pt (acac)(2), and CuO as the precursors were dispersed in NaCl and annealed at different temperatures with an H(2)-containing atmosphere. As the annealing temperature increased, the chemical order parameter (S), average particle size (D), coercivity (H(c)), and saturation magnetization (M(s)) of FePt and FePtCu NPs increased and the size distribution range of the particles became wider. The ordered degree, D, H(c), and M(s) of FePt NPs were greatly improved by adding 5% Cu. The highest S, D, H(c), and M(s) were obtained when FePtCu NPs annealed at 750 °C, which were 0.91, 4.87 nm, 12,200 Oe, and 23.38 emu/g, respectively. The structure and magnetic properties of FePt and FePtCu NPs at different annealing temperatures were investigated and the formation mechanism of FePt and FePtCu NPs were discussed in detail.