Physical characteristics of Pb2FeSbO6 double perovskite for thermoelectric applications

Abstract

The structural, mechanical, electronic, magnetic, optical, and thermoelectric properties of Pb₂FeSbO₆ double perovskite are investigated using full-potential linear augmented plane-wave (FP-LAPW) method incorporating the generalized gradient approximation (GGA) and GGA plus onsite Coulomb parameter (GGA+U). Pb₂FeSbO₆ crystallizes in a ferromagnetic (FM) cubic structure (space group Fm-3m) with lattice constants of 8.072Å, in good agreement with experimental data. The compound exhibits ductile behavior, as assessed by Poisson and Pugh's ratios. It shows an integer magnetic moment of 5.00μ_B per formula unit and demonstrates semiconductor behavior with bandgaps as follows: under GGA, the band-gap is 2.347eV (Γ-X) in spin-up and is 1.208eV (X-Γ) in spin-down; under GGA+U, the band-gap is 2.923eV (X-Γ) in spin-up and is 1.665eV (X-X) in spin-down. Optical properties reveal strong absorption in the ultraviolet range, and thermoelectric evaluation suggests a promising figure of merit (ZT_max≈1.0 at 300K). These findings underscore the potential of Pb₂FeSbO₆ for thermoelectric and optoelectronic applications.