Electromagnetic and absorption properties of U-type barium hexaferrite-epoxy composites

In the present study, U-type barium hexagonal ferrite (Ba4Co2Fe36O60) powder was synthesized by solid state reaction route. The synthesized ferrite powder was further transformed into a series of toroidal shaped ferrite-epoxy composites with different volume concentrations (42.6, 47.2, 50.6 and 54.3 volume percentages) of ferrite powder in epoxy matrix. The prepared U-type barium hexagonal ferrite powder and fabricated ferrite-epoxy composites were characterized for surface morphology, phase formation and magnetic properties by FESEM, XRD and VSM techniques respectively. Complex permittivity (εr = ε′ − jε″) and complex permeability (µr = µ′ − jµ″) of the fabricated composites were computed using an Agilent E8364B vector network analyzer in the frequency range of 2-18 GHz. The computed permittivity and permeability data of U-type ferrite composites were employed in the calculation of return loss (RL) of fabricated composites with varying thickness. The minimum RL was observed as −42.1 dB for the absorber with thickness of 3 mm and the bandwidth achieved was 8.5 GHz for RL ≤ −10 dB. Based on the above results these composites have potential use as excellent microwave absorbers in 2-18 GHz frequency range.