Synergistic Zn–Zr Co-Doping Enables High-Performance Microwave Absorption in M-Type Barium Ferrite

The development of high-performance microwave absorbers is essential for mitigating electromagnetic pollution. M-type barium ferrite (BaFe 12 O 19 ) exhibits excellent chemical stability and strong magnetic anisotropy; however, its application is hindered by poor impedance matching and low dielectric loss. Here we show that co-doping with Zn and Zr in BaZn x Zr x Fe 12−2x O 19 , combined with coupled strain and defect engineering, effectively addresses these limitations. Co-doping induces lattice expansion, grain refinement, and the formation of point defects such as oxygen vacancies and Fe 2+ /Fe 3+ redox pairs, which enhance interfacial polarization and ferromagnetic resonance. At x  = 0.3, the material achieves optimal impedance matching and a high attenuation constant, with a minimum reflection loss of − 29.26 dB at 12.16 GHz and an effective absorption bandwidth of 3.64 GHz. This remarkable performance surpasses that of conventional single-dopant systems, resulting from the synergistic enhancement of defect-induced dipole polarization, grain-boundary-mediated interfacial polarization, and ferromagnetic resonance, collectively optimizing attenuation while preserving near-unity impedance matching. These findings establish Zn–Zr co-doping as a promising strategy for developing next-generation microwave absorbers with environmental stability.