Interfacial polarization of different MnO2 crystal anchored on Ti3AlC2 to enhance the microwave absorption

Hierarchical MAX phase materials constructed with different MnO₂ crystal were designed for microwave absorbers. Different MnO₂ crystal loaded on Ti₃AlC₂ had an abundant and differentiated interfaces. Compactly loaded on the surface of Ti₃AlC₂, α-MnO₂/β-MnO₂ was a nanorod and δ-MnO₂ was a flower, but ε-MnO₂ was spherical separating from the Ti₃AlC₂. Relying on the synergistic effects of the interfacial and defect dipole polarizations, the optimal RL of Ti₃AlC₂@α-MnO₂ and Ti₃AlC₂@β-MnO₂ hybrids were -46.5 dB at 3.6 mm and -44 dB at 2.7 mm, respectively. The RL of Ti₃AlC₂@δ-MnO₂ hybrid was regulated by the matching thickness (-46.8 dB at 6.1 mm and -20 dB at 2 mm) and the broad EAB is 4.84 GHz. However, the RL of Ti₃AlC₂@ε-MnO₂ hybrid cannot reach -10 dB within the thickness of 1.0–5.0 mm, demonstrating the worst attenuation performance. This work offers an opportunity to elucidate the relationship between heterogeneous interface and microwave absorption.