Effect of co-doping on intrinsic parameters and absorption properties of micro-nano barium ferrite hollow ceramic microspheres

Micro-nano barium ferrite hollow ceramic microspheres (HCMs) was prepared by low-temperature self-reactive quenching technology combined with heat treatment. Effect of Co(NO₃)₂ on intrinsic parameters and absorption properties of micro-nano barium ferrite HCMs was investigated. The results indicated that the introduction of Co(NO₃)₂ modified the intrinsic parameters of HCMs, i.e. the types of phase composition increased, the particle size distribution became broader and the density increased. However, the surface morphology was unchanged. The change of intrinsic parameters after introducing Co(NO₃)₂ enhanced the permittivity and permeability significantly in the 0.1–18 GHz range. In the range of 2–4 mm of thickness, the minimum reflectivity value of Co-doping HCMs-paraffin composites could reach −31.2 dB corresponding to a thickness of 2.5 mm, moreover, the bandwidth <−10 dB was obtained in 5.4–18 GHz. Generally, we could rationally deduce that the absorption properties of barium ferrite HCMs can be improved significantly by introducing Co²⁺, furthermore, it could be modulated by adjusting thickness.