Synthesis of FePtAu nanoparticles in high-boiling-point solvents

Partially ordered FePtAu nanoparticles with size around 8 nm were prepared by the simultaneous decomposition of iron pentacarbonyl and reduction of gold acetate and platinum acetylacetonate. The high boiling point chemical, hexadecylamine, was used as a solvent, and 1-adamantanecarboxylic acid was used as a stabilizer. The final temperature was controlled between 300°C-360°C during synthesis, where disordered FePt particles could be partially transformed into the ordered L1₀ phase. A nonmagnetic mechanical stirrer was used in order to avoid agglomeration of the fct-FePt particles during synthesis. XRD patterns of as-made samples showed weak superlattice peaks, indicating partial chemical ordering of the FePtAu particles. The coercivities of partially transformed as-made particles vary from a few hundred oersteds to a few thousand oersteds, depending on the concentration of gold additive and the temperature of synthesis. Dynamic coercivity measurements yield thermal stability factors and switching volumes that are slightly higher than would be expected for noninteracting particles.