We report here a new synthetic route to FePt nanoparticles using a stoichiometric mixture of Na2Fe(CO)4 and Pt(acac)2. The structure of FePt nanoparticles, their size, chemical composition, and magnetic property can be controlled by various synthetic parameters, such as the solvent type, nature, and molar ratio of surfactants and stabilizers, synthesis temperature, and purification process. Partially ordered fct (L10) nanoparticles with room temperature magnetic coercivity can be synthesized directly in tetracosane solution at 389 degrees C. The fcc FePt synthesized in nonadecane can be transformed into the magnetically important fct phase at 430 degrees C without significant particle sintering.

We report the synthesis of FePt magnetic nanoparticles using Na2Fe(CO)4 and Pt(acac)2 as reagents. This method allows good control over particle stoichiometry and ensures efficient mixing of Fe and Pt atoms in the alloy at the atomic scale. The use of a variety of different high boiling solvents and different surfactants allows control over particle size. Materials can be prepared in the disordered face-centered cubic (fcc) structural form and converted to the high magnetocrystalline anisotropy face centered tetragonal (fct or L10 structure) at lower temperatures than those prepared by other routes. By using solvents such as nonadecane, docosane, and tetracosane, we can prepare samples directly in the fct form. Preformed fcc particles prepared by this method can also be transformed in solution to the fct structure. Samples have been characterized by a combination of diffraction, electron microscopy, thermogravimetric, and magnetic measurements.

A simple microwave heating method has been used for the stoichiometrically controlled synthesis of FePt and FePd nanoparticles using Na 2 Fe(CO) 4 and Pt(acac) 2 /Pd(acac) 2 as the main reactants. By varying the solvents and surfactants, the microwave assisted reactions have shown a significant advantage for the rapid production of monodisperse fcc FePt nanoparticle metal alloys which can be converted to the fct phase at low temperatures (364 uC). Microwave reactions at high pressure (closed system) have led to the direct formation of a mixture of fcc and fct phase FePt nanoparticles. Room temperature structural and magnetic properties of materials have been characterized by X-ray diffraction, HRTEM and magnetic measurements. The onset of ordering has been investigated by in situ high temperature X-ray diffraction studies.

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