Facile synthesis of NiFe2O4/Ni3Fe/LAS core-shell-like composites with improved impedance matching and microwave absorption properties

Abstract

The rapid development of communications technology has exacerbated the deterioration of the electromagnetic environment and therefore there is an urgent need to develop efficient electromagnetic wave absorbing materials. Based on the idea of constructing the ferrite-alloy-glass multiphase heterogeneous microstructure, core-shell-like NiFe2O4/Ni3Fe/LAS nanocomposites has been successfully prepared by using sol-gel, hydrothermal and in situ reduction methods. In which, NiFe2O4 and Ni3Fe provide strong magnetic and dielectric losses, while the introduction of the LAS (Lithium aluminum silicate, Li2O–Al2O3–SiO2 glass) wave-transparent phase modulates the complex dielectric constant, and effectively improving impedance matching. The multi-component nature of NiFe2O4/Ni3Fe/LAS produces abundant heterogeneous interfaces, and the strong interfacial polarization contributes to the attenuation of electromagnetic waves. At the thickness of 2.3 mm, the reflection loss (RL) of NiFe2O4/Ni3Fe/LAS reaches −50.7 dB at 11.36 GHz with an effective absorption bandwidth (EAB) of 5.04 GHz, while at 2.0 mm the EAB is up to 7 GHz. Importantly, the NiFe2O4/Ni3Fe/LAS nanocomposites achieve effective absorption (RL < −10 dB) in the C, X and Ku bands (5–18 GHz). This work is expected to offer prospects for high-performance and ultra-broadband composite microwave-absorbing materials.