Hexagonal Ti2SC with high hardness and brittleness: a first-principles study

The equation of state (EOS), electronic and elastic properties of Ti2SC have been investigated by first-principles calculations. The calculated EOS is highly consistent with recent experimental reports. The calculated band structure shows that Ti2SC is metallic. The charge density distributions indicate that the covalent nature of the Ti–S and Ti–C bonds is mainly responsible for the high value of the bulk modulus and hardness. By analyzing the ratio between bulk and shear moduli, we conclude that Ti2SC is brittle in nature.