(Ti0.2V0.2Cr0.2Nb0.2Ta0.2)2AlC-(Ti0.2V0.2Cr0.2Nb0.2Ta0.2)C high-entropy ceramics with low thermal conductivity

In recent years, the microstructure and physicochemical properties of high-entropy ceramics have received much interest by the combination of multiple principal elements. Herein, (Ti0.2V0.2Cr0.2Nb0.2Ta0.2)(2)AlC-(Ti0.2V0.2Cr0.2Nb0.2Ta0.2)C high-entropy ceramics (M2AlC-MC HECs) were prepared by the spark plasma sintering (SPS) technique, attributing to the structural and chemical diversity of MAX phases. The microstructure of M2AlC-MC HECs was characterized from micron to atomic scales, and the phase composition of M2AlC-MC HECs was analyzed by a combination of Maud and Rietveld analysis. The results indicate the successful solid solution of Ti, V, Cr, Nb, and Ta atoms in the M-site of the 211-MAX configuration, and all the samples show a classic layered structure. The weight percentage of (Ti0.2V0.2Cr0.2Nb0.2Ta0.2)(2)AlC in the M2AlC-MC HECs was more than 90%. Furthermore, the thermoelectric properties of M2AlC-MC HECs were investigated for the first time in this study, and the electrical conductivity and thermal conductivity of HECs are 3278 S cm(-1) and 2.78 W m(-1) K(-1)at 298 K, respectively.