Tunable complex permeability and enhanced microwave absorption properties of BaNixCo1−xTiFe10O19

In order to achieve a broader absorption bandwidth with smaller reflection loss (RL) in electromagnetic absorber, nickel ions (Ni2+) were employed to partially occupy the sites of cobalt ions (Co2+) in BaCoTiFe10O19. Ni-doped barium hexaferrite (BaNixCo1−xTiFe10O19) powders were synthesized via the sol-gel combustion method. Subsequently, the microwave absorbing composites were prepared by mixing the BaNixCo1−xTiFe10O19 powders with the paraffin. As the doped Ni2+ ions were in augment, the grain size of BaNixCo1−xTiFe10O19 decreased from 400 nm to 50 nm. Based on the electromagnetic parameters measured by the vector net-analyzer in the frequency of 0.5-18 GHz, it was found that the peaks of the complex permeability shifted to the high frequency region with the increase of the doped Ni. Moreover, the composite (x = 0.4) possessed a maximum reflection loss (RL) of −47.49 dB at 13.28 GHz with a matching thickness of 2.0 mm. It also had a bandwidth below −20 dB ranging from 12.36 GHz to 18 GHz, which has great potentials applications in the high frequency fields of the microwave absorbing materials.