Multifunctional BiFeO3 composites: Absorption attenuation dominated effective electromagnetic interference shielding and electromagnetic absorption induced by multiple dielectric and magnetic relaxations

BiFeO3 (BFO) grains prepared by molten salt method were fabricated in paraffin wax based composite structure to evaluate electromagnetic interference (EMI) shielding and electromagnetic (EM) absorption in 2-18 GHz. In the composites, BFO750 paraffin wax composite exhibits excellent EMI shielding and EM absorption performance. The EMI shielding effectiveness of BFO750 paraffin wax composite surpasses 10 dB, and its reflection loss shows three absorption peaks which reach −17 dB. The absorption efficiency and attenuation constant are close to 80% and 70, respectively. The results demonstrate that absorption attenuation is the dominant mechanism of EMI shielding and EM absorption. This is attributed to multiple dielectric and magnetic relaxations, where electric and magnetic dipoles coexisting in the composite can respond intensively to electromagnetic wave in the frequency range and thus cause high electromagnetic loss. The work highlights BFO composites as promising multifunctional materials in electromagnetic wave protection fields.