Reductive decomposition of CoPt(CO)4(dppe)Me/NaCl composite powder (2 : 98 CoPt precursor : NaCl mass ratio) at 650 °C under getter gas (9 : 1 N2/H2) gives black CoPt/NaCl nanocomposites with minimal CoPt nanoparticle coalescence. Aqueous dissolution of the NaCl support permits isolation of ferromagnetic L10 CoPt nanoparticles of ca. 11 nm average diameter as free-flowing black powders. As-prepared CoPt nanopowders exhibit moderate coercivity (4.0 kOe) at 300 K and high coercivity (26.0 kOe) at 5 K consistent with formation of polydisperse L10 CoPt nanoparticles having high purity and high crystallinity. Co1Pt1 nanoparticles are formed with good control of alloy stoichiometry using a single-source precursor by a convenient, scalable single-step process.
