First-principles calculations to investigate the structural, electronic, optical, mechanical, and thermodynamic properties of double perovskites Ba2WB′O6 (B′ = Co, Fe, Mn, Ni, and Zn)

We utilized the WIEN2K code within the DFT framework to comprehensively investigate Ba2WBˈO6 (Bˈ = Mn, Fe, Co, Ni, Zn) double perovskite compounds. Structural stability, assessed by Goldsmith's tolerance factor (tG), revealed values close to unity, indicative of stable cubic perovskite structures. The Birch-Murnaghan's equation of state optimization determined ground states, unveiling trends in lattice constant (a0) and bulk modulus (B) for different cations. Structural and phonon stability were confirmed by negative energy formation and real frequencies in phonon calculations. DFPT results affirmed the thermodynamic stability of all compounds. Electronic band structure calculations identified Ba2WMnO6 and Ba2WNiO6 as conductors, while Ba2WCoO6 and Ba2WZnO6 were insulators with 3.7 eV and 3.8 eV band gaps, respectively. Ba2WFeO6 demonstrated semiconducting properties with a 2.37 eV band gap. Density of States (DOS) analysis supported the electronic band structure. Optical conductivity analysis revealed increasing values at higher energy ranges, followed by gradual decreases, differing between conductors and insulators. Absorption coefficient indicated potential suitability for optoelectronic devices, and refractive index analysis highlighted trends in material transparency. To understand fundamental properties, thermodynamic characteristics (thermal expansion coefficient, heat capacities, Debye temperature) were analyzed across a wide pressure (0–30 GPa) and temperature (0–1600 K) range.