Microwave absorption performance enhanced by high-crystalline graphene and BaFe12O19 nanocomposites

Abstract

The nanocomposites, consisting of BaFe12O19 ferrite and few-layer graphene sheets (FL-GSs) in various weight ratios (1−9 wt. %), were fabricated by a mechanical mixing method. The high-crystalline FL-GSs were prepared by direct current arc discharge evaporation of pure graphite electrodes in an H2–Ar gas mixture. We measured the electromagnetic properties, including effective magnetic permeability and effective permittivity in addition to microwave absorption performance, of the FL-GSs/BaFe12O19 nanocomposites compared with the pristine BaFe12O19 nanoparticles (NPs). The nanocomposite FL-GSs/BaFe12O19 with the optimal performance (6 wt. % FL-GSs) exhibited an effective microwave absorption (<−10 dB) bandwidth of 5.8 GHz with a thickness of 2.2 mm, 53% higher than that of the pristine BaFe12O19 NPs. Meanwhile, this nanocomposite had the minimum reflection loss of −49.7 dB at 8.4 GHz with a thickness of 2.8 mm, three times greater than those without FL-GSs. These performances result from a simultaneous increase in both magnetic and dielectric losses possibly due to synergistic effects of BaFe12O19 and FL-GSs. In such nanocomposites, both magnetic loss from BaFe12O19 and dielectric loss from FL-GSs contribute to the absorbing performances. Adding FL-GSs as dielectric fillers enhances the impedance matching of the nanocomposites compared with the pristine BaFe12O19 NPs based on the magnetic loss alone. Our results indicate that the incorporation of high-crystalline nanocarbon materials into ferrite oxides can provide high microwave absorption intensity and broad effective absorption bandwidth, while maintaining high thermal stability.