Effect of milling time on dynamic permeability values of reduced carbonyl iron filled composites

• Flaky-shaped carbonyl iron fillers were fabricated using ball-milling method.
• The ball-milling strongly influences particle morphology and magnetic properties.
• The flaky-shaped fillers significantly enhance the permeability of composites.
• Study the effect of volume concentration on permeability and resonance frequency.

Flaky-shaped carbonyl iron fillers were fabricated using ball-milling and followed by annealing. Their morphology and particle size distribution, static and high-frequency magnetic properties were studied.For flaky-shaped filler composites, the permeability significantly enhances, as compared with sphere-shaped filler composite. The maximum real and imaginary permeability, μ′ and μ″, increase from 5 to 8 and from 2 to 5.3, respectively, while resonance is shifted to lower frequency, from 7 GHz to about 5 GHz. The increase in μ′ and μ″ has its origin in the flaky shape of carbonyl iron fillers. The composites with ball-mill time of 48–96 h have the optimum high-frequency properties. Also, the effect of volume concentrations on static and dynamic magnetic properties is studied for sphere-shaped carbonyl iron filler composites.