Potential of sub-micron-sized Fe-Co particles for antenna applications

High frequency properties of (a) as-synthesized and (b) flattened by ball milling Fe-based alloys particles and their potential as antenna materials is reported. The high frequency properties of Fe-Co nanoparticles exhibited a resonance peak in the range of a few gigahertz (GHz), and the resonance peak shifted to a higher region for decreasing particle size. However, magnetic permeability was not high enough to be used as high performing electromagnetic wave absorbers. On the other hand, the permeability of Fe-Ni particles at 1 GHz was 2.5 and the magnetic loss was 0.36. However, permeability was enhanced to a value of more than 3 and the magnetic loss decreased by more than half, when the dispersibility and planular aggregates were realized through ball milling. Additional experiments suggested that the particle aggregation had greater influence in the high frequency properties than the composition and magnetic properties. Similarly, when Fe50Co50 particles were also subjected to ball milling, their magnetic loss decreased below the values achieved by Fe-Ni and suggested the possibility of becoming a potential candidate for antenna applications. (C) 2012 American Institute of Physics. [doi:10.1063/1.3678296]