Fe₃O₄-CuO-MgNb₂O₆ Ternary Ceramics with Heterogeneous Interfaces for Efficient Microwave Absorption

Fe₃O₄-CuO-MgNb₂O₆ ternary ceramics were synthesized using solid reaction sintering and the microwave absorption performance was investigated. Remarkable absorption characteristics were observed in the composite material, with optimal reflection loss of −53.3 dB at 8.6 GHz and effective bandwidth of 3.8 GHz (6.9–10.7 GHz) at a thickness of 2.8 mm. The decrease in porosity and simultaneous increase in grain size impact the motion of domain walls, leading to magnetic loss. Furthermore, reduction in porosity facilitates closer proximity of grains, thereby reducing high-resistivity borders and improving the mobility of carriers. Consequently, this leads to an increase in the imaginary part of the complex permittivity. The introduction of three phases and grain growth synergistically contribute to interface and dipolar polarization, further enhancing the dielectric loss and properties related to microwave absorption. The Ansys HFSS (high-frequency structure simulator) results also prove that larger grain size positively affects impedance matching and microwave absorption performance in ceramics. By controlling the grain size of Fe₃O₄-CuO-MgNb₂O₆ ternary ceramics, it becomes possible to tailor the microwave absorption properties.