Density functional theory study of the structural, electronic, mechanical, and thermal properties of Hf6Ta2O17

The structural, electronic, mechanical, and thermal properties of Hf6Ta2O17 are studied using density functional theory. Helmholtz free energy is computed for various symmetry constraints on the structure during lattice optimization atomic configuration relaxation. energies calculated from Γ-point phonon frequencies demonstrate a preference slightly lowered symmetry, preferring triclinic rather than experimentally determined orthorhombic symmetry. Elastic constants obtained symmetry-enforced (i.e., orthorhombic) used to calculate structure’s mechanical including its bulk, shear, Young’s moduli, Poisson ratio, Pugh longitudinal shear sound velocities, Debye temperature. Furthermore, Born criteria predicts that mechanically stable. Finally, electronic band presented found exhibit large indirect gap.