Synthesis and electromagnetic wave absorption performances of a novel (Mo0.25Cr0.25Ti0.25V0.25)3AlC2 high-entropy MAX phase

Herein, a novel kind of high-entropy MAX phases, (Mo0.25Cr0.25Ti0.25V0.25)3AlC2 powders were successfully synthesized by a newly proposed two-step solid state reaction process. The oxidation experiments demonstrate that the oxidation products of Al2Mo3O12 and rutile TiO2 are formed at about 600 and 800 °C, respectively. Besides, the dielectric and electromagnetic (EM) wave absorption properties of (Mo0.25Cr0.25Ti0.25V0.25)3AlC2 powders and those after oxidation at different temperatures were also examined. The results show that the as-synthesized (Mo0.25Cr0.25Ti0.25V0.25)3AlC2 powders possess excellent EM wave absorption performances with the minimum reflection loss (RL) of -45.80 dB (at 1.7 mm thickness) and the maximum effective absorption bandwidth (EAB) of 3.6 GHz (at 1.5 mm thickness). After oxidation at 400–800 °C, due to the coupling of conductivity loss and polarization loss, (Mo0.25Cr0.25Ti0.25V0.25)3AlC2 powders can retain good EM wave absorption properties in a certain frequency range. In this paper, the effects of oxidation on EM wave absorption properties of high-entropy MAX phases were systematically investigated for the first time. This work manifests that high-entropy MAX phases are promising EM wave absorbing candidates and can maintain good EM wave absorption performances after oxidation.