Shape control of FePt nanocrystals

FePt nanocrystals were prepared by simultaneous reduction of platinum acetylacetonate and thermal decomposition of iron pentacarbonyl in properly chosen solvents/surfactants. A variety of FePt nanocrystals, including nanowires, nanorods, nanocubes, and nanosized multipods, were successfully obtained. The shape control was realized by simply varying synthesis parameters. The as-synthesized nanocrystals, having chemically disordered fcc structure, are found to be superparamagnetic at room temperature and their ferromagnetic-superparamagnetic transition temperature is size dependent that increases with particle size. The as-synthesized FePt nanocrystals were transformed to the chemically ordered L 1 0 structure upon heat treatment, which exhibits hard magnetic properties with coercivity as high as 25 kOe.