Synthesizing CNx heterostructures on ferromagnetic nanoparticles for improving microwave absorption property

Abstract

To solve high-frequency electromagnetic interference and pollution issues, microwave absorption materials composited with dielectric and magnetic loss capacities have been employed for optimizing such problems. In this work, we demonstrate an effective approach for synthesizing graphite shells and CNx heterostructures outside the ferromagnetic nanoparticles (FMNPs) via an in-situ microwave-assisted heating approach. Ascribing to the high conductivity and eddy loss property, FMNPs act as the “heating points” during treatment, realizing the electromagnetic energy into thermal energy for in-situ decomposing the urea precursor. Microstructure characterizations coupled with microwave absorption performance reveal that the loss capacity for FMNP@CNx is correlated with particle sizes, substituted heteroatom contents, and impendence matching. In particular, the Fe@CNx nanoparticles treated in 1 min obtain a minimized RL of −26.8 dB at 5.0 GHz and an effective absorption bandwidth (<-10 dB) of 5.4 GHz with the thickness in a range of 3.8 ~ 5.0 mm. The present study exhibits a novel approach for in-situ synthesizing graphite shells and substitutional heterostructures of ferromagnetic materials and has promising potentials to extend to other high magnetic loss materials.