Mechanical and thermodynamic properties of YB2C2 under pressure

The pressure dependence of structure, mechanical and thermodynamic properties of Yttrium diborocarbides (YB2C2) up to a maximum pressure of 70 GPa have been investigated systematically by the first-principles calculations. The calculated structure parameters are in a good agreement with the experimental data. The elastic constants were calculated, the results show that YB2C2 is mechanically stable throughout the pressure range covered. The polycrystalline elastic modulus, ductility and hardness are discussed in details. All of them gradually increase linearly with increasing pressure. Our calculations also show that YB2C2 will transition from brittleness to ductility around 52 GPa. Finally, the anisotropic behavior, the Debye temperature and melting temperature had been studied.