Enhanced microwave electromagnetic characteristics of porous ZnO/Ni/ZnxNiyFe3−x−yO4 hybrid micro-hexahedra

A green versatile glucose-engineered precipitation/sintering process was developed for the selective, large-scale growth of porous ZnO/Ni/ZnxNiyFe3−x−yO4 micro-polyhedra. Modulation over composition, grain size, and specific surface area can be expediently achieved by changing the Fe3+/Ni2+/Zn2+ molar ratio (γ) and sintering temperature (Ts). Relationships between structure and properties were investigated. High Ts and the appropriate addition of Zn2+ improved the microwave electromagnetic properties of the materials. The ZnO/Ni/ZnxNiyFe3−x−yO4 hybrid micro-hexahedra obtained at 700 °C and γ = 2:0.5:0.5 showed a minimum reflection loss (RL) of −36.52 dB at 10.0 GHz with absorbing frequency (RL ≤ −20 dB) from 4.59 GHz to 18.0 GHz, corresponding to 1.7 mm-5.5 mm coating thickness. The enhanced absorption performances were attributed to the additional multiphase interface, multiresonance, and good matching and absorbing properties of the hybrid materials. The obtained magnetic hybrid materials exhibited promising applications in magnetic devices, catalysis, solar energy conversion, and electromagnetic wave-absorbing materials.