First principles calculations of the properties of Sr3In2As4 and Eu3In2As4 Zintl phases.

Structural, bonding, electronic, elastic and optical properties of X₃In₂As₄ (X = Sr, Eu) Zintl phases are calculated theoretically. We used ab-initio simulations using the Vienna Ab Initio Simulation Package (VASP). Structural analysis reveals that Sr₃In₂As₄ and Eu₃In₂As₄ belong to the orthorhombic crystal system. The calculated structural parameters are in good agreement with previously reported results. Electronic properties (band structure and DOS) disclose that both Zintl phases are direct band gap semiconductors. The phonon-based band structures, total and partial density of states confirmed the dynamical stability due to the unavailability of imaginary phonons in all high symmetry directions. The studied Zintl phases meet the criteria of mechanical stability. The computed elastic properties indicate that the Eu₃In₂As₄ has high hardness and shows more stability in comparison with Sr₃In₂As₄. For both Zintl phases, calculations unveil the high anisotropic behavior of mechanical properties. Significant anisotropy was observed for the parallel and perpendicular components in the frequency-dependent optical spectra. [ABSTRACT FROM AUTHOR]