The Study On Microwave Absorption Performances Of Doped M Type Barium Ferrite And The Doped Ferrites-graphene Composite Materials

This research aimed at solving the mainly present problem of microwave absorbing materials with poor microwave attenuation, narrow microwave absorption bandwidth and large thickness of absorber. For obtaining composites with excellent microwave absorption performance, the ferrites possessing perfect magnetic loss were combined with graphene which have good dielectric loss. This article discussed the magnetic properties and the microwave absorption performances of the doped ferrites. Moreover, the morphology and microwave attenuation properties of the composites of doped M-type barium ferrite and graphene were preliminary investigated. The test results are as follows:The doped ferrites BaNixCo1-xTiFe10O19 were synthesized by sol-gel combustion method. The crystal size of the ferrites was ranging in 50-400 nm, which was refined with the increment of x. In addition, as the doped Ni2+ ions were in augment, the coercivity of the ferrites increased while the saturation magnetization had a slight increase and then decreased with the increasing x. Based on the electromagnetic parameters,the peaks of complex permeability gradually shifted to the high frequency region with the augmentation of the doped Ni. Moreover, the microwave absorption performance of the ferrites was improved. The maximum reflection loss of BaNi0.4Co0.6TiFe10O19 could reach-47.49 dB and the absorption bandwidth below-20 dB was from 12.36 GHz to 18.00 GHz. For BaNi0.2Co0.8TiFe10O19, the maximum reflection loss was-48.68 dB, and the absorbing bandwidth less than-15 dB reached 7.26 GHz.Mn2+and Ni2+ were used to co-doped in the ferrite of BaCo TiFe10O19. As a result, the Ba(MnNi)0.2Co0.6TiFe10O19 and Ba(MnNi)0.25Co0.5TiFe10O19 were prepared by sol-gel combustion method. The crystal sizes for both of the ferrites were in the range of 50-400 nm. Moreover, the absorption performance of the doped ferrites was further improved. The absorbing bandwidth less than-20 d B of Ba(MnNi)0.25Co0.5TiFe10O19 was from 13.20 GHz to 18.00 GHz and the maximum reflection loss could reach-69.20 dB. In addition, the maximum reflection loss of Ba(MnNi)0.2Co0.6TiFe10O19 was-52.80 dB, and the absorption bandwidth below-15 dB could reach 5.80 GHz.The composites of rGO/ BaNi0.2Co0.8TiFe10O19 with different mass ratio were synthesized. From the SEM images of the composites, it can be obviously found that the particles of BaNi0.2Co0.8TiFe10O19 were dispersed on the surface of graphene sheets and between layers of graphene sheets. Moreover, the value of saturation magnetization decreased with the augmentation of graphene in the composite. In addition, the microwave absorption performance of the composites was improved. When the mass ratio of rGO/BaNi0.2Co0.8TiFe10O19 was 1:20, the bandwidth of reflection loss less than-10 dB for the composite could reach 8.30 GHz while the thickness of the sample was only 1.2 mm.