Ab initio study of AlCu2M (M = Sc, Ti and Cr) ternary compounds under pressures

The structural, electronic and elastic properties of the AlCu2M (M = Sc, Ti and Cr) compounds in the pressure range of 0–100 GPa was investigated based on density functional theory. The calculated lattice parameters of the AlCu2M compounds at zero pressure and zero temperature are in very good agreement with the existing experimental data. The bulk modulus, shear modulus and Young’s modulus increases with the increase of pressure, which indicates that higher materials hardness may be obtained when increasing pressures. The bulk modulus and Young’s modulus of AlCu2Cr is the greatest under pressure. The shear modulus of AlCu2Ti is the highest above 30 GPa, while that of the AlCu2Sc is the strongest below 30 GPa. The calculated B/G values at zero and higher pressure indicated that they are ductile materials. The electronic densities of states and bonding charge densities have been discussed in details, revealing these compounds exhibit half-metallic behavior. In addition, the pressure dependences of Debye temperatures of AlCu2M compounds have also been calculated. The results indicate that Debye temperatures increase with increasing pressure.