First-principle investigation of pressure and temperature influence on structural, mechanical and thermodynamic properties of Ti(3)AC(2) (A = Al and Si)

The mechanical and thermodynamic properties of Ti3AlC2 and Ti3SiC2 have been investigated by the first principles. The structure is briefly discussed, the compressibility of Ti(3)SiC(2 )is better than Ti3AlC2 . Its mechanical stability is confirmed by the elastic constant, and the results show that the pressure can enhance the resistance to the deformation. In addition, the ductility is also improved with the pressure increasing. The elastic anisotropy is enhanced with increasing the pressure. Finally, the temperature and pressure dependences of thermodynamic properties of Ti(3)AlC(2)and Ti3SiC2 are evaluated by the quasi-harmonic Debye approximation theory, and analyzed the effect of pressure and temperature on the Debye temperature, bulk modulus, heat capacity and the thermal expansion coefficient. The Debye temperature and bulk modulus decrease with increasing the temperature but increase with increasing the pressure. The temperature and pressure have opposite influences on the heat capacity, moreover, the ability of Ti3AlC2 to absorb or release heat is stronger than that of Ti-3 SiC2.