Controlled Morphologies and Intrinsic Magnetic Properties of Chemically Synthesized Large-Grain FeCo Particles

The high-purity FeCo particles with particle size ranging from 100 nm to 5 μm are fabricated using a direct chemical method. The controlled morphologies of the FeCo samples vary from nearly-spherical to urchin-like or cubic shape under optimal reaction conditions. Very slight surface oxidation is observed in these large-grain FeCo particles. It shows a low coercivity with 91 Oe for the nearly-spherical FeCo particles, while a much higher coercivity of 236 Oe is observed in the urchin-like samples, which can be mainly ascribed to their different morphologies and particle sizes. High saturation magnetization of 205–211 A/m²/kg can be achieved in these micron-level FeCo particles due to their high purity and single body-centered cubic (bcc) phase structure. The composition-controlled FeCo particles with different Fe/Co atom ratios can be obtained by adjusting the reaction temperature, which results in their variable saturation magnetization. The relative simple and low-cost chemical synthesis of large-grain FeCo particles promise their potential use in complicated shape and miniaturized FeCo-based magnetic components.