Structural and magnetic properties of the ordered FePt3, FePt and Fe3Pt nanoparticles

The FexPt100-x nanoparticles (NPs) with different nominal atomic rations (30 <= x <= 80) were synthesized at 700 degrees C by the sol-gel method. The structure, morphology and magnetic properties of the samples were investigated. When the Fe content in the Fe-Pt alloy NPs was 30 at%, FePt3 NPs were successfully synthesized. With the increase in Fe content up to 50 at%, it was found that the superlattice reflections (0 0 1) and (1 1 0) appeared, which indicated the formation of the L1(0)-FePt phase. Meanwhile, the FePt3 fraction was reduced. When the Fe content increased to 60 at%, single-phase L1(0)-FePt NPs were synthesized. The coercivity (Hc), saturation magnetization (Ms) and chemical order parameter S for Fe60Pt40 NPs were as high as 10,200 Oe, 17.567 emu/g and 0.928, respectively. With the further increase of the Fe content to 80 at%, only Fe3Pt phase existed and the Hc of the Fe3Pt NPs decreased drastically to 360 Oe. (C) 2013 Elsevier Inc. All rights reserved.