Elastic and optoelectronic properties of CaTa2O6 compounds: Cubic and orthorhombic phases.

Abstract Using first principles density functional theory (DFT) simulations, the structural, electronic, optical and elastic properties of CaTa 2 O 6 oxide for cubic and orthorhombic phases are studied by highly accurate (FP-LAPW) method within the GGA + U approximation. The calculated lattice parameters are consistent with available experimental data. The electronic band structure calculations have shown that the band gaps in CaTa 2 O 6 are equal to 3.08 eV and 4.40 eV for the cubic and orthorhombic structures, respectively. For both the phases the main optical properties, e.g., absorption coefficient, dielectric constant, energy loss function, reflectivity are calculated and discussed in detail in the spectral range 0–14 eV. Cubic and orthorhombic phases exhibit significantly different optical characteristics. The electronic bonding characters of CaTa 2 O 6 with different symmetries are explored via charge density distribution mapping. Strong covalent bonding character dominates in both the phases of CaTa 2 O 6. Elastic properties of CaTa 2 O 6 for cubic and orthorhombic phases are also investigated. The stress strain method is used for the determination of elastic constants in both the phases. The bulk modulus, shear modulus, Young's modulus, along with the important elastic anisotropy factors and Poisson's ratio are studied in detail. Graphical abstract Image 1 Highlights • Electronic, and optical properties of CaTa 2 O 6 in cubic and orthorhombic phases are studied. • Energy band gaps were equl to 3.08 and 4.40 eV, respectively. • Optoelectronic features are due to Ca-s, Ta-p, O-p orbitals in (c.p.), Ta-p and O-(o.p.) • The Zener factor and Poison's ratio confirm elastically anisotropic characteristics. [ABSTRACT FROM AUTHOR]