Mechanism of microwave dielectric response in carbon nanofibers enabled BCN composites

Abstract

Nano-sized carbon materials are elegant multifunctional fillers that exhibit superior electromagnetic absorbing/shielding properties compared to conventional carbon fillers. In this paper, dielectric behavior of carbon nanofibers (CNFs) enabled BCN ceramics over the frequency range of 2–18 GHz was analyzed experimentally and theoretically. Experimental results have shown that microwave frequency dispersion of CNFs/BCN composites differs greatly from that described by classical Debye theory. The corresponding mechanism of dielectric response has been studied through an equivalent circuit approach. The modeling results demonstrate that, in addition to electrical current loss of CNFs, breakpoints which act as effective capacitance also play an important role in dielectric response of as-prepared CNFs/BCN composites. In other words, the induced current loss and polarization loss under alternating electromagnetic field dominate the principal mechanism in microwave attenuation for CNFs/BCN composites. All these are beneficial to regulation and optimization of microwave absorption performance of novel CNFs functionalized composites.