Exploring the Structural, Electronic and Optical Properties of Ba₂Nbx-1VxRhO₆ Double Perovskite: A DFT Investigation

الملخص

    This work provides a complete first-principles study of the structural, electronic and optical properties of the double perovskite Ba₂Nb_1-xV_xRhO₆ with the doping amount x=0.25, 0.50, 0.75 and 1.0. Structural optimization shows that the compositions all exhibit cubic symmetry with Fm3̅m space group, and are both geometrically and dynamically stable, based on tolerance factor calculations and phonon dispersion analysis. The electronic structure calculations show that as Nb is replaced by V, the band gap decreases dramatically, resulting in 1.473, 1.046, 0.785 and 0.565 eV values, and changes the transition from direct to an indirect band gap character with higher concentration of V. These electronic changes are mainly due to the increased level of hybridization between the V-3d/Rh-4d states and the O-2p orbitals. The optical response studied using the complex dielectric function, absorption coefficient, extinction coefficient, reflectivity, optical conductivity and energy-loss spectrum, shows significant strengthening in the visible and near-infrared range as V content increases. For the full substituted compound Ba₂VRhO₆, a distinct redshift at the absorption edge and enhanced plasmon resonance at high energies is seen. In conclusion, the tunable band-gap property and enhanced optical characteristics of Ba₂Nb_1-xV_xRhO₆ perovskites suggest that they may be useful candidates for high-efficiency solar cells, broadband photodetectors, and multifunctional optoelectronic devices.