A facile solution phase synthesis of directly ordering monodisperse FePt nanoparticles

The ordered Pt-based intermetallic nanoparticles (NPs) with small size show superior magnetic or catalytic properties, but the synthesis of these NPs still remains a great challenge due to the requirement of high temperature annealing for the formation of the ordered phase, which usually leads to sintering of the NPs. Here, we report a simple approach to directly synthesize monodisperse ordered L1₀-FePt NPs with average size 10.7 nm without further annealing or doping the third metal atoms, in which hexadecyltrimethylammonium chloride (CTAC) was found to be the key inducing agent for the thermodynamic growth of the Fe and Pt atoms into the ordered intermetallic structure in the synthetic process. In particular, 10.7 nm L1₀-FePt NPs synthesized by the proper amount of CTAC show a coercivity of 3.15 kOe and saturation magnetization of 45 emu/g at room temperature. The current CTAC-assisted synthetic strategy makes it possible to deeply understand the formation of the ordered Pt-based intermetallic NP in solution phase synthesis.