Grain size influence on soft ferromagnetic properties in Fe–Co nanoparticles

A systematic investigation of the room temperature M–H hysteresis loops and saturation magnetization has been conducted in a series of Fe–Co composites with grain size ranging from micron to nanoscale, where parameters like the particle size of the Fe and Co components, stabilizing additives are varied. Nanoparticles of Fe, Co and Fe–Co were synthesized using a patented, high throughput microwave plasma technique. Static and dynamic magnetic studies were done using a Physical Property Measurement System (PPMS). Our results show that excellent soft ferromagnetic properties are retained even when the overall grain size in the nanoparticles was in the 10 to 20 nm range. Saturation magnetization (Ms) >100 emu/g was obtained in Fe–Co nanoparticles. Our experiments demonstrate the feasibility of commercial mass production of these materials where the advantages associated with the nanoscale grain size distribution can be combined with the high Curie temperature and soft ferromagnetic properties for a variety of applications.