Wideband and enhanced microwave absorption performance of doped barium ferrite

To achieve stronger microwave attenuation and larger bandwidth in electromagnetic absorber, the nickel ions (Ni 2+ ) and manganese ions (Mn 2+ ) were employed to partially replace the cobalt ions (Co 2+ ) in BaCoTiFe 10 O 19 , and the doped barium hexaferrite (Ba(MnNi) 0.2 Co 0.6 TiFe 10 O 19 and Ba(MnNi) 0.25 Co 0.5 TiFe 10 O 19 ) powders were synthesized via the sol–gel combustion method. Subsequently, the microwave absorbing composites were prepared by mixing the ferrite powders with the paraffin. The X-ray diffraction (XRD) patterns of the doped ferrites confirmed the formation of the M-type barium ferrite , and no other types of barium ferrite could be found. Based on the electromagnetic parameters measured by the vector net-analyzer, it was found that the composite (Ba(MnNi) 0.2 Co 0.6 TiFe 10 O 19 ) possessed a minimum reflection loss of −52.8   dB at 13.4   GHz with a matching thickness of 1.8   mm and the bandwidth below −15   dB was 5.8   GHz. Moreover, the maximum attenuation of Ba(MnNi) 0.25 Co 0.5 TiFe 10 O 19 could reach −69   dB when its thickness was 1.8   mm, and also the bandwidth less than −20   dB was ranging from 13.2   GHz to 18   GHz. Thus, Ba(MnNi) 0.2 Co 0.6 TiFe 10 O 19 and Ba(MnNi) 0.25 Co 0.5 TiFe 10 O 19 could be the good microwave absorbers, which have great potentials to be applied in the high frequency fields of the microwave absorbing materials.