Highly enhanced microwave absorption for carbon nanotube/barium ferrite composite with ultra-low carbon nanotube loading

Abstract

• A facile approach for fabricated carbon nanotube (CNT)/barium ferrite (BaFe 12 O 19 ) composite with good dispersion of carbon nanotube was developed. • In view of the thermal stability of CNT in different atmosphere and the formation mechanism of BaFe 12 O 19 , uniform dispersion of CNT was achieved in the CNT-BaFe 12 O 19 composite. • The as-prepared CNT/BaFe 12 O 19 composite exhibits excellent microwave absorption ability. Barium ferrite (BaFe 12 O 19 ) is considered as potential microwave absorption (MA) material thanks to the large saturation magnetization, high Curie temperature, and excellent chemical stability. The integration of carbon nanotube (CNT) can improve the dielectric loss of BaFe 12 O 19 for further enhanced MA performance, nevertheless, the MA performance is still not desirable because of the poor CNT dispersion in the CNT/BaFe 12 O 19 composites, which usually prepared via the ball-milling method, unless high CNT loading was used. Herein, according to the thermal stability of CNT in different atmosphere and the formation mechanism of BaFe 12 O 19 from precursor, CNT was introduced in the precursor of BaFe 12 O 19 uniformly during auto-ignition process and calcined under different atmosphere. When CNT loading is only 2.0 wt%, the CNT/BaFe 12 O 19 composites obtained exhibits a minimum reflection loss ( R L min ) of -43.9 dB and effective bandwidth (with RL < -10 dB) of 3.9 GHz with the thickness of 1.5 mm, which are much superior to -10.2 dB and 2.2 GHz for pure BaFe 12 O 19 , and -13.6 dB and 2.5 GHz for CNT/BaFe 12 O 19 composite prepared by ball-milling method. These results may pave the way to design high-performance BaFe 12 O 19 based microwave absorbers.