First-principles investigations of phase stability, mechanical, thermal and optical properties of Ti3(Al1-xSix)C2 solid solutions

By means of first-principles calculation, we explored the physical properties of substituting Al with Si atom in layered ternary carbide Ti3AlC2. Present results revealed that the Ti3(Al1-xSix)C2 (x = 0.0-1.0) compounds under study are thermodynamically stable brittle materials, and the mechanical properties can be improved to some extent by Si-doping. Moreover, all the compounds show metallic character with a strong TiC bonding and possess a rather stiff lattice and good thermal conductivity. It is notable that these compounds show highly anisotropic at photon energies lower than 18.0 eV. Specifically, all the Ti3(Al1-xSix)C2 compounds exhibit high reflectivity, nearly reaching the maximum of ∼98%, in the photon energy range of 0-12.5 eV. Therefore, we expect that Si-doped Ti3(Al1-xSix)C2 solid solutions are possibly a good candidate for coating materials in ultraviolet region.