Electromagnetic attributes a dominant factor for the enhanced EMI shielding of PANI/Li0.5Fe2.5−xGdxO4 core shell structured nanomaterial

Abstract

A core-shell structured PANI/Li0.5Fe2.5−xGdxO4 (0.0 ⩽ x ⩽ 0.2) nanocomposite material has been prepared by in situ emulsion polymerization method as is evidenced by X-ray diffraction and Scanning electron microscopy. Transmission electron microscopy confirms the formation of core (ferrite)-shell (PANI matrix) structured nanocomposite material. These materials have been investigated for electromagnetic interference (EMI) shielding in the X-band (8–12 GHz) frequency range. Higher shielding effectiveness (SET) of around 42 dB has been obtained in this study than many other systems reported recently. The main contributing factor has been ascribed to the absorption (SEA = 34–36 dB) instead of reflection (SER = 4.0–6.3 dB), owing to the enhancement in the electromagnetic attributes. Effect of increasing Gd3+ ion content in PANI/Li0.5Fe2.5−xGdxO4 nano-composite has been analyzed for the electromagnetic attenuation. It depicts a decreasing trend of SE with Gd3+ doping except for x = 0.2 sample. This has been attributed to the increasing particle size of ferrites, resulting into the decrease in dielectric (ε′ = 59–56 at 9.5 GHz) attributes owing to increased grain to grain contact. Higher value of SE for x = 0.2 sample can be due to the secondary phase formation in ferrite, which increases the number of grain boundaries and thereby increases ε′. However, increasing magnetization with Gd3+ doping is less likely a factor affecting shielding as compared to dielectric attributes. Such a material with high SE demonstrates the potential of these materials for making future microwave shields. Keywords: PANI, Nano-ferrites, Magnetic properties, Dielectric properties, EMI shielding