Direct synthesis and size selection of ferromagnetic FePt nanoparticles

A one-step synthesis of L1(0) FePt nanoparticles ca. 17.0 nm in diameter by reductive decomposition of the single-source precursor, FePt(CO)(4)dppmBr(2), on a water-soluble support (Na2CO3) is demonstrated. Direct conversion of a FePt(CO)(4)dppmBr(2)/Na2CO3 composite to a L1(0) FePt/Na2CO3 nanocomposite occurs at 600 degrees C under getter gas with metal-ion reduction and minimal nanoparticle coalescence. Triturating the resulting nanocomposite with water simultaneously dissolves the sodium carbonate solid support and precipitates the formed fct FePt nanoparticles. As-prepared FePt nanoparticles are ferromagnetic and exhibit coercivities of 14.5 kOe at 300 K and 21.8 kOe at 5 K. When capped by functionalized methoxypoly(ethylene glycol) surfactant molecules, as-prepared, polydisperse ferromagnetic FePt nanoparticles can be dispersed and size-selected by fractional precipitation.