Two birds with one stone: Fe-doped CuAlO₂ ceramics for efficient microwave absorption and high emissivity

Semiconductor oxides are ideal candidates for future electromagnetic wave absorption and thermal management due to their hole-conducting properties. However, in practical applications, due to its limited conductivity, its development and application in the field of electromagnetic wave absorption and thermal management are greatly limited. The CuAl_1-xFe_xO₂ ceramics were synthesized using the high-temperature solid-phase method to study their microwave absorption and infrared emissivity characteristics. The introduction of Fe significantly improves the electromagnetic wave absorption and emissivity characteristics of CuAlO₂ ceramics. The effects of Fe doping on the dielectric constant, permeability, microstructure, and surface morphology of the composite were systematically analyzed. The results show that Fe doping leads to lattice distortion and the introduction of defects, which effectively improves the conductivity and polarization loss of the material, thus enhancing the dielectric loss and magnetic loss mechanisms of the material and obtaining excellent microwave absorption performance. The results show that when the doping amount of Fe is 3 %, the minimum reflection loss RLmin can reach −50.41 dB, and the effective absorption bandwidth EAB is 4.2 GHz. When the doping amount of Fe is 9 %, the infrared emissivity reaches a peak of 0.936. The porous structure further enhances the absorption and radiation properties of CuAl_1-xFe_xO₂ ceramics. It is further indicated that CuAl_1-xFe_xO₂ ceramics have great application potential in electromagnetic wave absorption and thermal management.