Tunable Microwave Absorbing Properties of CoFe2O4/PANI Nanocomposites

Abstract

The design of CoFe2O4/PANI interfaces can significantly enhance a material's dielectric loss ability at high frequency. This paper presents a simple method to generate CoFe2O4/PANI interfaces to enhance microwave absorption and attenuation at high frequency. Cobalt ferrite nanoparticles were mixed with PANI at various wt.%. X-ray diffraction of nanocomposites indicates that the structure of the core material has a spinel structure and demonstrates the formation of CoFe2O4/PANI nanocomposites. The particle size of ferrite and polyaniline powders were measured using transmission electron microscopy. The particle size of CoFe2O4 is found to be 20 nm. The saturation magnetization (Ms) of all the nanocomposites were found to be decreasing with decrease of ferrite content, while coercivity (Hc) remained at the value corresponding to pure cobalt ferrite. Because the CoFe2O4/PANI interface induces a strong dielectric loss effect, all of these materials achieved broad effective frequency width at a coating layer as thin as 1.9 mm. The complex permittivity (e′ and e″) and permeability (μ′ and μ″) were collected by a vector network analyser and the absorbing properties were calculated according to transmission theory. e′, e″ and μ″ increases with an increase of PANI, whereas μ′ decreases. The absorption peak shifted to the high-frequency side with PANI. These results showed that a wider absorption frequency range could be obtained by adding different polyaniline content in cobalt ferrite.