A new layer compound Nb4SiC3 predicted from first-principles theory

We predicted a new layer compound Nb4SiC3 using the first-principles method. The structural stability, mechanical, electronic, theoretical hardness and optical properties of Nb4SiC3 were investigated. A stable Nb4SiC3 phase appears in the alpha-type crystal structure. Moreover, the predicted Nb4SiC3 is a metal and exhibits covalent nature. Nb4SiC3 has a theoretical hardness of 10.86 GPa, which is much higher than Nb4AlC3; at the same time, it is more ductile than Nb4SiC3. The strong covalent bonding in Nb4SiC3 is responsible for its high bulk modulus and hardness. Nb4SiC3 exhibits slightly anisotropic elasticity. Furthermore, its optical properties are also analysed in detail. It is shown that Nb4SiC3 might be a better candidate material as a coating to avoid solar heating than Ti4AlN3.