Controllable synthesis of MOF-derived FexNi1−x@C composites with dielectric–magnetic synergy toward optimized impedance matching and outstanding microwave absorption

The impedance matching is a very important part to influence materials’ microwave absorption performance. However, a way to further discuss the impedance matching is still weak. We build a novel dielectric–magnetic impedance matching (DMIM) model to analyze the real part and imaginary part of materials’ impedance matching. To verify the practicality of the DMIM model, using MIL-100(Fe) as precursor, a series of FexNi1−x@C are synthesized via one-step pyrolysis by controlling the samples’ Fe–Ni ratio, changing their dielectric loss tangent and magnetic loss tangent and successfully regulating their impedance matching to optimize microwave absorption properties. In addition, the minimum reflection loss for MOF-derived Fe0.8Ni0.2@C can arrive at -71.3 dB at 10.3 GHz with a thickness of 3.1 mm, and the effective absorption bandwidth is 5.3 GHz. And combining with the RLGC equivalent circuit model to further indicate the FexNi1−x@C’s energy loss mechanism. The method of using DMIM model and RLGC model to discuss materials’ impedance matching and energy loss mechanism paves a new way to fabricate high-performance microwave materials with balanced electromagnetic distribution and further reveal the materials' microwave absorbing mechanism.