FePt and Fe nanocomposite by annealing self-assembled FePt nanoparticles

We present a simple fabrication of FePt and Fe nanocomposite by annealing self-assembled FePt nanoparticles. 5 nm FePt nanoparticles were prepared by simultaneous reduction of platinum acetylacetonate and thermal decomposition of iron pentacarbonyl in the presence of oleic acid and oleylamine as stabilizers. The as-synthesized FePt nanoparticles can self-organize well on a clean SiO/Si substrate and, then, were annealed in a vacuum using a rapid thermal process at different temperatures for 0.5 h. It is found that the annealing temperature plays a key role in determining the final products. The samples annealed at 550 degreesC and 700 degreesC consist of a FePt-face-centered-tetragonal (fct) phase with a coercivity of around 1000 and 8800 Oe, respectively, whereas, the samples annealed at 580 degreesC are composed of two phases: one is the FePt-fct phase and the other is a Fe-body-centered-cubic phase. The hysteresis loop of the sample annealed at 580 degreesC is also two-phase like with a kink at low field and its coercivity is around 8000 Oe. That indicates that Fe can be segregated from FePt by proper annealing, forming FePt and Fe nanocomposites. (C) 2004 American Institute of Physics.