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https://doi.org/10.1007/s11664-020-08352-y  2020 The Minerals, Metals & Materials Society

Tunable Microwave Absorbing Properties of CoFe2O4/PANI Nanocomposites K. PRAVEENA

1,3

and M. BOUOUDINA2

1.—Department of Physics, Palamuru University, Mahabubnagar, Telangana State 509001, India. 2.—Department of Physics, College of Science, University of Bahrain, PO Box 32038, Sakheer, Kingdom of Bahrain. 3.—e-mail: [email protected]

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 (l¢ and l¢¢) were collected by a vector network analyser and the absorbing properties were calculated according to transmission theory. e¢, e¢¢ and l¢¢ increases with an increase of PANI, whereas l¢ 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. Key words: Ferrites, polyaniline, complex permittivity, complex permeability, reflection coefficient, microwave absorption

INTRODUCTION With the rapid development in miniaturization and densification of electronic products,1,2 the severe heat dissipation problem has become a serious issue affecting stability and reliability,3,4 thereby making electromagnetic interference (EMI) a more serious issue that affects human health and interferes with the normal operation of other electronic devices.5 To address this problem, magnetic + ploymer nanocomposites known as high-

(Received January 20, 2020; accepted July 22, 2020)

performance electromagnetic wave absorbing materials are of great interest to scientists due to their ease of preparation, low cost, large magnetic momentum, reliability and high electrical resistivity.6 Hence, there is a desire for the development of high-performance electromagnetic wave absorbing materials. These materials have drawn worldwide attention because they are able to attenuate EM wave energy by converting it into thermal energy.7,8 Ideally, electromagnetic wave absorption materials