Synthesis of L10-(FeyPt100-y)100-xCux nanoparticles with high coercivity by annealing at 400 °C.

(FeyPt100-y)100-xCux nanoparticles with various compositions were synthesized by the simultaneous polyol reduction of Pt(acac)2 and Cu(acac)2 and the thermal decomposition of Fe(CO)5. The as-made particles had a disordered fcc structure and an average diameter of ∼4.8 nm. The result of x-ray diffraction indicated a transformation from fcc structure to fct structure in some samples after annealing at 400 °C for 1 h, and the c/a ratio of lattice constant decreased with increasing Cu content. The doping of Cu clearly plays a significant role on the reduction of the ordering temperature in the ternary (FeyPt100-y)100-xCux alloy. In addition, the ordering of (FeyPt100-y)100-xCux nanoparticles is significantly dependent on the composition of Fe and Pt. As a result, (Fe47Pt53)74Cu26 nanoparticles have the coercive fields of ∼10 and ∼2 kOe at 10 K and room temperature, respectively. [ABSTRACT FROM AUTHOR]