First-principles study of the structural, phonon, elastic, and thermodynamic properties of Al_3Ta compound under high pressure

Abstract

We have investigated the phonon, elastic and thermodynamic properties of L1 2 phase Al 3 Ta by density functional theory approach combining with quasi-harmonic approximation model. The results of phonon band structure shows that L1 2 phase Al 3 Ta possesses dynamical stability in the pressure range from 0 to 80 GPa due to the absence of imaginary frequencies. The pressure dependences of the elastic constants C i j , bulk modulus B, shear modulus G, Young's modulus Y , B/G and Poisson's ratio ν have been analysed. The elastic constants are satisfied with mechanical stability criteria up to the external pressure of 80 GPa. The results of the elastic properties studies show that Al 3 Ta compound possesses a higher hardness, improved ductility and plasticity under higher pressures. Further, we systematically investigate the thermodynamic properties, such as the Debye temperature Θ, heat capacity C p , and thermal expansion coefficient α, and provide the relationships between thermal parameters and pressure.