MnO2‐Magnetic Core‐Shell Structured Polyaniline Dependent Enhanced EMI Shielding Effectiveness: A Study of VRH Conduction

Abstract

AbstractThe core‐shell structured based Polyaniline/MnO2 composites were synthesized by chemical oxidation method, wherein MnO2 particles acts as a magnetic core while polyaniline chains wrapped over these particles acts as a shell. Four different loading concentrations of MnO2 particles (10, 20, 30 and 40 wt %) were used to investigate the effect of MnO2 concentration on the EMI shielding effectiveness. X‐ray diffraction (XRD) studies performed on pristine MnO2 and composite samples reveal the polycrystalline nature of the MnO2 particles and semi‐crystalline nature of the composites with a sharp peak around 25° over a broad hump. Vibrating sample magnetometry (VSM) studies performed on the pristine MnO2 particles as well composite sample (S4) at higher loading (40 wt %) concentration of MnO2 suggest the ferromagnetic nature at room temperature. The charge transport properties of the prepared samples have been investigated under variable range hopping (VRH) conduction. Mott's three dimensional VRH model has been found to be applicable for conduction in the present samples. The dc conductivity of the prepared samples is found to increase with MnO2 loading concentrations, which suggest their possible validity for EMI shielding applications. Therefore, the prepared samples are analyzed for EMI shielding properties in the frequency range of 8.2 to 12.4 GHz (X‐band). The sample prepared with 30 wt% of MnO2 has as much as 50 dB shielding effectiveness, which is quite higher than that required for industrial application (∼30dB).