Exploring the magneto-optic, thermoelectric, and electronic properties of Ba2GdXO6 (X = Nb, & U) double perovskites by employing the DFT approach

Abstract

The thermoelectric, magneto-optic, and electronic characteristics of the materials Ba₂GdXO₆ (X = Nb, & U) have been computed, using first principles investigations. The GGA + U potential approximation is used to predict the ground state characteristics of the materials. The materials are found to have a stable crystallographic structure by obtaining the tolerance factor in the cubic (Fm-3 m) symmetries. They are also found to be thermodynamically and dynamically stable. The electronic band structures suggest that the Ba₂GdNbO₆ is direct band gap semiconducting with band gaps of 2.3 eV (spin up) and 2.5 eV (spin down) and the half-metallic nature of Ba₂GdUO₆. The DOS predicts the magnetic nature of the materials. The integral values 7 (µ_B) and 8 (µ_B) of total magnetic moments of Ba₂GdNbO₆ and Ba₂GdUO₆, respectively, support the ferromagnetic nature of the materials. The ferromagnetic nature of the material was determined by analyzing the energy–volume optimization curve at the most stable configuration, in comparison with the antiferromagnetic (AFM) and non-magnetic (NM) phases. The optical characteristics, including the real and imaginary parts of the dielectric functions, along with other optical parameters, have been computed and discussed to understand the optical behavior of the materials. The overall ZT and PF analysis of the materials suggests that the Ba₂GdUO₆ shows excellent thermoelectric performance as compared to the Ba₂GdNbO₆ material. The thermoelectric, magneto-optic, and electronic characteristics of the materials Ba₂GdXO₆ (X = Nb, U) have been computed using first principles investigations. The GGA + U potential approximation is employed to predict the ground state characteristics, while the main focus remains on GGA + U. However, band gap values were also calculated using the HSE06 functional, yielding 5.358 eV for Ba₂GdNbO₆ (spin up), 5.384 eV for Ba₂GdNbO₆ (spin down), 4.420 eV for Ba₂GdUO₆ (spin up), and 3.891 eV for Ba₂GdUO₆ (spin down), confirming that these materials are direct band gap semiconductors. The materials demonstrate a stable crystallographic structure within cubic (Fm-3 m) symmetries, verified by tolerance factor calculations, indicating thermodynamic and dynamic stability. The electronic band structures classify Ba₂GdNbO₆ as a direct band gap semiconductor, while Ba₂GdUO₆ exhibits half-metallic behavior. The DOS analysis further suggests the magnetic nature of the materials, with total magnetic moments of 7 µB and 8 µB for Ba₂GdNbO₆ and Ba₂GdUO₆, respectively, supporting their ferromagnetic character. This ferromagnetic nature is confirmed by energy–volume optimization, where ferromagnetic configurations show greater stability compared to antiferromagnetic (AFM) and non-magnetic (NM) phases. Optical properties, including the real and imaginary parts of the dielectric functions, along with other optical parameters, have been calculated to elucidate the materials’ optical behavior. The ZT and power factor (PF) analyses indicate that Ba₂GdUO₆ exhibits superior thermoelectric performance compared to Ba₂GdNbO₆.