Thermally stable polyaniline and Mn0.25Co0.75Fe2O4 nanocomposite as an efficient material for high frequency applications at room temperature.

Ferrimagnetic Mn0.25Co0.75Fe2O4 (MCF) nanoparticles were synthesized via sol–gel autocombustion method. Polyaniline (PANI) and PANI nanocomposites with MCF as filler (PANI/MCF) were synthesized through chemical oxidative in-situ polymerization of aniline under the presence of varying weight percentage of the MCF (10%, 20% and 50%). The MCF, PANI and PANI/MCF nanocomposites were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analyzer (TGA), field emission scanning electron microscopy equipped with elemental detection (FESEM-EDAX) and vibrating sample magnetometer. The XRD and FTIR spectra confirmed the formation of pure phase with high crystallinity for all the samples. TGA study showed the increased thermal stability of PANI with addition of MCF. MCF and PANI/MCF nanocomposites showed ferrimagnetic hysteresis loop under external magnetic field at room temperature. Additionally, the ac conductivity, dielectric and electrical properties as a function of frequency ranging from 100 Hz to 120 MHz, were investigated for all the samples using impedance analyzer at room temperature. Dielectric, TGA and magnetic studies showed that PANI/MCF with 50 weight percentage of MCF has maximum ac conductivity, thermal stability and moderate magnetic properties. Hence, it could be a potential candidate to be used as dielectric material in high frequency capacitors and for electromagnetic interference shielding material at high frequency. [ABSTRACT FROM AUTHOR]