Facile synthesis and magneto-alignment effect on the microwave absorption property of NiCo2O4/NiO/Co3O4 composites

A simple method of high-temperature ignition to metalorganics was successfully used to synthesise composites of NiCo2O4, NiO and Co3O4. A detailed investigation of the composite's microwave absorption properties revealed the magneto-alignment effect. By closely arranging NiCo2O4, NiO and Co3O4 nano-particles in epoxy resin, the magnetic exchange is strengthened under the influence of a magnetic field. The sample without magnetic alignment, S0, exhibited poor absorption efficiency with reflection loss (RL) values hardly reaching − 10 dB across a frequency range of fixed and different thicknesses (2–18 GHz). In comparison, the oriented composite exhibited higher permittivity and permeability, particularly in the high-frequency range. Considering the improved impedance matching and reasonable adjustment of dielectric and magnetic losses, the microwave absorbing performance of the oriented composite substantially improved in the 10–14 GHz range. The minimum RL is reduced to − 45.11 dB with an effective bandwidth of 4 GHz. Herein, we present a straightforward method to increase the microwave absorption performance of NiCo2O4 by modifying the macroscopic order and degree.