First-principles investigation of mechanical, electronic and optical properties of Al3Sc intermetallic compound under pressure

Abstract

The dependences of the structural, mechanical, electronic and optical properties of Al3Sc intermetallic compound on pressure were studied using the first-principles method based on the density functional theory with generalized gradient approximation and local density approximation methods. The results showed the pressure has the significant impact on the equilibrium volume, mechanical properties, electronic properties and optical properties of Al3Sc. The calculated structural and mechanical parameters (i.e., bulk modulus (B), shear modulus (G), Young’s modulus (E), Poisson’s ratio (v), and Debye temperature (θD)) were in good agreement both with the previously reported experimental and theoretical results at zero pressure. Additionally, all these parameters presented the linearly increasing dependences on the external pressure. The B/G ratios indicated the Al3Sc crystals should exhibit brittle deformation behavior at 0–50GPa. The universal anisotropic index (AU) signified the Al3Sc compound was near elastically isotropic under zero pressure, and may become anisotropic as the pressure increased. Further, the pressure-dependent behaviors of density of states (DOS), Mulliken charge and bond length were discussed. In the DOS spectra, the values of DTotalAl3Sc, DpAl and DdSc were all reduced as the pressure was elevated at the Fermi level. However, the relative contributions to the DTotalAl3Sc from Alp state were found slightly increased, and Sc3d state remained leveled. Finally, the optical conductivity spectra were simulated as a function of the external pressure. The two peak positions in such spectra were successfully identified and compared with other reported values.