Solid solution strategy modulated defects engineering of (Cr1-xVx)2AlC MAX phase toward superior electromagnetic wave absorption

Defects engineering is an effective strategy for manipulating electromagnetic parameters and enhancing electromagnetic wave (EMW) absorption capacity. However, the relationship between them is not clear, especially in solid solution structures. In this work, a series of (Cr1-xVx)(2)AlC MAX phase solid solutions with layered structure were prepared via tuning the ratio of Cr and V to explore their EMW absorption performance. The experimental results indicated that the doping of V atoms at the M-site could effectively regulate its impedance matching and EMW absorption properties by introducing appropriate numbers of defects in the crystal, such as twin boundaries, dislocations and lattice distortions. Among them, if Cr: V = 3:1, Cr1.5V0.5AlC, as radar absorption materials, could reach a strong reflection loss of - 51.8 dB at the frequency of 12.8 GHz under an ultra-thin thickness of 1.3 mm. The reflection loss value could attain - 10 dB in a wide frequency range of 2.7-18 GHz and thickness range of 1-5 mm. In addition, after high temperature and acid-alkali immersion treatment, this sample still had good EMW absorption capability, and the effective absorption bandwidth was enhanced from 2.3 to 2.6 GHz after concentrated acid immersion or 3.1 GHz after concentrated alkali immersion. This work has great reference significance for the research and development of high-performance MAX-based EMW absorption materials in harsh environments.