Ultrabroad bandwidth and matching characteristics for spinel ferrite composites with flaky fillers

Spinel ferrite flakes Ni(0.97-x)Zn(x)Co(0.03)Fe(2)O(4) with x=0.5 and 0.65 are prepared for use as fillers in electromagnetic composites. The composites with the flaky fillers exhibit greatly enhanced high-frequency and attenuation properties. The complex permeability, mu(0)' and mu(max)'' , is enhanced by about 500%-700%, and the relative attenuation bandwidth W(R) is increased by 300%-440%, as compared to those for composites with conventional spherical fillers. W(R) achieves 90% of the theoretically maximum relative bandwidth. The composites with the spinel ferrite flaky fillers are powerful and potential candidates as electromagnetic attenuation materials with ultrabroad bandwidth at microwave L, S, and C bands. (C) 2010 American Institute of Physics. [doi:10.1063/1.3485809]