Tunable Microwave Absorbing Properties of CoFe 2 O 4 /PANI Nanocomposites

The design of CoFe 2 O 4 /PANI interfaces can significantly enhance a material's dielectric loss ability at high frequency. This paper presents a simple method to generate CoFe 2 O 4 /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 CoFe 2 O 4 /PANI nanocomposites. The particle size of ferrite and polyaniline powders were measured using transmission electron microscopy. The particle size of CoFe 2 O 4 is found to be 20 nm. The saturation magnetization ( M s ) of all the nanocomposites were found to be decreasing with decrease of ferrite content, while coercivity ( H c ) remained at the value corresponding to pure cobalt ferrite. Because the CoFe 2 O 4 /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 ( ε ′ and ε ″) and permeability ( μ ′ and μ ″) were collected by a vector network analyser and the absorbing properties were calculated according to transmission theory. ε ′, ε ″ 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.