Synthesis of flake shaped carbonyl iron/reduced graphene oxide/polyvinyl pyrrolidone ternary nanocomposites and their microwave absorbing properties

Abstract

Ternary composites of flake shaped carbonyl iron/reduced graphene oxide/polyvinyl pyrrolidone (CI/rGO/PVP) were synthesized via the assembly of positively charged CI and negatively charged graphene oxide (GO) with subsequent chemical reduction and PVP nanoparticles decoration. The preparation of such ternary composites was confirmed by various characterization methods including ξ-potential, scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive X-ray spectrometer (EDS), RAMAN scattering spectroscopy, and X-ray diffraction (XRD). The influence of PVP concentration on the morphology and microwave absorbing property of CI/rGO/PVP composites was studied systematically. The hysteresis loops of pristine flake shaped CI, binary intermediate products and ternary final composites were measured by vibrating sample magnetometer (VSM) to illustrate their statics magnetism characteristics. The microwave absorbing properties of nanocomposites were calculated based on the analysis of electromagnetic parameters measured by vector network analyzer (VNA). According to the relative complex permittivity and relative permeability, dielectric loss of the ternary composites is mainly attributed to the orientational and interfacial polarization, while magnetic loss is prominently ascribed to eddy current loss, natural resonance, exchange resonance and hysteresis loss. The reflection loss (RL) calculation based on transmission line theories demonstrates that as-synthesized composites possess excellent microwave absorbing properties and the product with moderate PVP concentration shows an ultra-wide low reflection (RL < −10 dB) band from 4.2 to 18 GHz with a coating thickness of 2.5 mm. The synergetic effect between dielectric and magnetic constituents with novel ternary nanostructure leads to their enhanced microwave absorbing properties. Furthermore, the addition of rGO with much lower density than CI reduces the density of composites, which makes the CI/rGO/PVP ternary composites a very promising material in microwave absorbing application.