Formation of monodisperse FePt alloy nanocrystals using air-stable precursors: fatty acids as alloying mediator and reductant for Fe3+ precursors.

High quality FePt nanocrystals were synthesized by a simple and high performance synthetic method in a hydrocarbon solvent. Instead of a toxic and dangerous Fe(CO)(5) precursor, air-stable and generic inorganic and organic iron salts were used as the iron precursors. Fatty acid molecules were identified as both efficient reducing reagents for the Fe(3+) precursors and as an alloying mediator. The alloying process occurred in a two-step fashion. The Pt nanocrystal seeds initially formed at relatively low temperatures, with the need to be stabilized by a small amount of amines. Conversely, the final FePt nanocrystals could be stabilized with fatty acids as the main ligands. The mechanisms revealed here not only help to understand the formation of alloy nanocrystals but also shed new light on the formation of transition metal oxide nanocrystals using metal fatty acid salts as the precursors.