Assessment of electromagnetic shielding efficacy of magnetic metal oxide nanoparticles and their application in electromagnetic shielding paints

Abstract

People are continuously exposed to electromagnetic waves emitted by mobile phones, base stations, computers, household electrical appliances, and nearby devices. Shielding against electromagnetic radiation is of great importance to avoid potential adverse effects on human health. This study addresses the development of electromagnetic shielding paints containing magnetic metal oxide nanoparticles. Magnetic metal oxide nanoparticles with a spinel ferrite structure, namely Fe3O4, CoFe2O4, and SnFe2O4, were synthesized using the co-precipitation method. Their structural, morphological, and magnetic properties were characterized through FTIR, XRD, TEM, and VSM measurements. Electromagnetic shielding efficacy was assessed within the 3.5–12.5 GHz frequency range using waveguide measurements. Notably, pure magnetic metal oxide nanoparticles exhibited limited shielding efficiency, but incorporating conductive materials like multi-walled carbon nanotubes improved the efficacy. Optimization studies, involved adjusting the nanoparticle-to-carbon nanotube ratios and coating thickness, demonstrated the best shielding to be with 50: 10 [MFe2O4:PEG]:mwcnt ratio (M :Fe, Co, Sn) and 0.720 mm thickness, achieving up to 99% of radiation shielding. The subsequent incorporation of the optimized magnetic composites into a water-based wall paint at a 1: 2 weight ratio demonstrated their effectiveness in shielding, successfully blocking 84 % of incoming radiation.