Synthesis and Magnetic Properties of Iron Phosphide Nanorods

Abstract

Iron phosphide nanorods were fabricated by the thermal decomposition of Fe(CO)5 in a solution containing magnetite nanoparticles, trioctylphosphine, and didodecyldimethylammonium bromide at 300 °C under an argon atmosphere. The length of the rods was varied from 30 to 260 nm, whereas the diameter of the rods was ∼8 nm by the multiple injections of Fe(CO)5. It was found that the rod size increased with the number of injections under the constant total injection concentration and reaction time. In addition, the size of the nanorods could be manipulated by changing the reaction time, reaction temperature, and seed concentration. These nanorods, composed of magnetite particles in the core and Fe2P in the shell, exhibit unique magnetic properties. The magnetic properties of nanorods characterized by a superconducting quantum interference device showed that the blocking temperature of the rods increased with rod length and reached a maximum when the length of the rods was ∼60 nm. With the longer rod length, the blocking temperature of the rods decreased with increasing rod size. We believe that our accomplishments to synthesize magnetic nanorods with a core−shell structure in a controlled manner will provide exciting new possibilities on the materials front.