Exploring optical behaviour based tantalum suggested Ba₂BTaO₆ (B = Gd and Yb) double perovskites for advanced photonics and optoelectronic devices

This study investigates the properties of the double perovskite compounds Ba₂BTaO₆ (B: Gd, Yb) using the DFT-based FP-LAPW method with various exchange–correlation potentials (GGA, GGA + U, and mBJ-GGA). The structural, electronic, magnetic, optical, and thermodynamic properties were analyzed. The results indicate that the Ba₂GdTaO₆ compound exhibits lower energy in ferromagnetic structure while Ba₂YbTaO₆ compound is more stable in ferrimagnetic configuration. The Goldschmidt tolerance factor "t" confirms the stability of both cubic structures. Additionally, the calculated elastic constants meet Born criteria, affirming the mechanical stability of these compounds. The cubic compounds Ba₂GdTaO₆ and Ba₂YbTaO₆ exhibit high stiffness and resistance to transverse bending. The Debye quasi-harmonic model successfully calculates the volume V, thermal capacity Cv, entropy S, and Debye temperature \({\theta }_{D}\) ${\theta }_D$ as functions of temperature and varying pressures. Optical analyses of Ba₂GdTaO₆ reveal its metallic nature, transparency in specific spectral ranges, and potential applications in satellite technology and EUV lithography. Ba₂YbTaO₆ displays interesting metallic properties from Plasmon oscillations, with notable differences in its infrared spectra. Notably, high-energy refractive index shows “super-luminescence”, which suggests potential for photonics applications.