Synthesis and assembly of monodisperse high-coercivity silica-capped FePt nanomagnets of tunable size, composition, and thermal stability from microemulsions

The synthesis of monodisperse FePt nanoparticles with tunable particle size over an extended range of 4-20 nm and excellent compositional control using microemulsions was analyzed. The advantages of this technique includes control of Fe/Pt ratios by providing a confined reaction environment, and facile dopant incorporation. It also include formation of outer shells through introduction and hydrolysis of oxide precursors, room-temperature synthesis, and the obviation of inert gases. Transmission electron microscopy revealed that the microemulsion technique yields FePt nanoparticles of controllable size and narrow distribution. Octadecanethiol capping facilitated assembly by inhibiting nanoparticle clustering at room temperature. The capping agent renders the particles dispersible in nonpolar solvents and facilitates the formation of ordered asemblies by limiting nanoparticles clustering. The positional order of the nanoparticles was disrupted due to organosilane decomposition.