Amorphous-Co@Nd(BO2)3/rGO magnetic nanocomposites as high-frequency, wide-bandwidth and light-weight microwave absorbing materials

Abstract

It is necessary to broaden absorption bandwidth, regulate applied frequency, reduce the weight and maintain strong absorption for magnetic microwave absorbing materials by constructing suitable material structures to satisfy the requirements for wide applications in various electromagnetic devices. In this work, well-structured amorphous-Co@Nd(BO2)3/rGO nanocomposites have been fabricated using a selective chemical reduction in a mixed aqueous solution containing Co2+ and Nd3+ ions along with GO sheets reduced by NaBH4 as the reductant, in which only Co2+ and GO but no Nd3+ ions were reduced. Very low coercivity of 0.4 Oe is achieved in amorphous-Co@Nd(BO2)3/rGO nanocomposites due to amorphous Co@Nd(BO2)3 core-shell nanoparticles uniformly anchored on rGO sheets. These soft magnetic rGO-based nanocomposites exhibit high-frequency microwave absorption performance including a minimum reflection loss (RLmin) value of −84.09 dB at 15.38 GHz for a 2.1 mm thickness at an applied frequency range (12.31–18 GHz) covering almost the entire Ku band. Moreover, a much wider absorption band of 7.24 GHz (10.67–17.89 GHz, RL ≤ −10 dB) with a 2.3 mm thickness along with a RLmin value of −35.92 dB is also achieved. These rGO-based magnetic composites also show good structural stability, low density and easily controlled material compositions along with facile chemical fabrication suitable for mass production, which promises their latent use in high-performance microwave absorbing devices. Crystallization behavior of a new amorphous Nd(BO2)3 phase was also investigated.