He Shu-Li et al 2007 Chinese Phys. 16 3536 doi:10.1088/1009-1963/16/11/062
He Shu-Li1, Peng Yin1, Liu Li-Li1, Jiang Hong-Wei1, Liu Li-Feng1, Zheng Wu1 and Wang Ai-Ling1
Show affiliationsIn this paper, Fe30Pt70/Fe3O4 core/shell nanoparticles were synthesized by chemical routine and the layered polyethylenimine (PEI)-Fe30Pt70/Fe3O4 structure was constructed by molecule-mediated self-assembly technique. The dimension of core/shell structured nanoparticles was that of 4nm core and 2nm shell. After annealing under a flow of forming gas (50%Ar2+30%H2) for 1h at or above 400°C, the iron oxide shell was reduced to Fe and diffused to Pt-rich core, which leaded to the formation of L10 phase FePt at low temperature. The x-ray diffraction results and magnetic properties measurement showed that the chemical ordering temperature of Fe30Pt70/Fe3O4 core/shell nanoparticles assembly can be reduced to as low as 400°C. The sample annealed at 400°C showed the coercivity of 4KOe with the applied field of 1.5T. The core/shell structure was suggested to be an effective way to reduce the ordering temperature obviously.
81.16.Be Chemical synthesis methods
Issue 11 (November 2007)
Received 6 March 2007, in final form 10 April 2007
He Shu-Li et al 2007 Chinese Phys. 16 3536
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