Calculations of physical properties of Ba2GdSbO6 (BGSO) double perovskite for thermoelectric and solar cell applications

First-principle investigations indicate that calculated and experimental lattice constant of rock-salt Ba2GdSbO6 (BGSO) double perovskite show close proximity. The BGSO is a mechanically stable, highly rigid, elastically anisotropic and brittle crystal with high melting temperature. Spin-polarized band structures predict its indirect band-gap semiconductor nature. Partially filled 4f and 5d states of Gd make BGSO strongly ferromagnetic and hence suitable for magnetic data storage device. Holes are the majority carriers in BGSO due to positive Seebeck coefficient. Large electronic figure-of-merit projects BGSO as a promising thermoelectric material. Several thermodynamic parameters are also calculated in the present study. Calculated specific heat at constant volume follows the Debye's T-3 and Dulong-Petit limit at very low and high temperature, respectively. Optical properties are calculated mainly in terms of complex dielectric function and other ancillary parameters. The indirect band-gap (>2.0 eV) semiconductor BGSO would have promising application in next generation low-cost tandem solar cells.