Anisotropic electrical and lattice transport properties of ordered quaternary phases Cr2TiAlC2 and Mo2TiAlC2: A first principles study

Electrical conductivities of Cr2TiAlC2 and Mo2TiAlC2 in a and c directions are calculated from semi-classic Boltzmann transport theory. The values are found to be σa=5.68×105S/m (6.56×105S/m) and σc=2.15×105S/m (2.69×105S/m) for Cr2TiAlC2 (Mo2TiAlC2) at 300 K. Using the phonon-mode Debye temperature and Slack-model, the lattice thermal conductivities in the two directions are also evaluated, and the values are κa=18.71W/m K (16.11 W/m K) and κc=0.48W/m K(0.25W/m K) for Cr2TiAlC2 (Mo2TiAlC2) at room temperature. The anisotropy in lattice thermal conductivity is found to be stronger than that of electrical conductivity. The predicted Seebeck coefficients and thermoelectric figure of merit (ZT) indicate that they are poor thermoelectric materials. Due to the relatively high conductivities, they might be used to fabricate high temperature conductive components in aerospace industry. In addition, our results in a direction have the direct implications for the relevant properties of MXenes (Cr2TiC2 and Mo2TiC2), produced from their bulk phases.