Hubbard's parameter influence on Ba2GdReO6 properties, a promising ferromagnetic double Pérovskite oxide for thermoelectric applications

Abstract

In this paper, an exhaustive investigation was carried out on the compound double Perovskite Ba2GdReO6 including its structural, electronic, magnetic and thermoelectric properties. This study is based on the density functional theory (DFT) and more explicitly on the full potential linearized augmented plane wave (FP-LAPW), in the context of different approximations as exchange and correlation potential such as: The generalized gradient approximation (GGA) and its corollary the Becke – Johnson approach modified by Trans-Blaha (TB - mBJ) for a better approximation of the gap, and the GGA + U approach (where U is the Hubbard correction term). After an analysis of the results obtained, it turns out that the double perovskite material Ba2GdReO6 is a ferromagnetic material and has a half-metallic character, moreover, this compound has an integral magnetic moment of 9µB, which is in accordance with the rule of Slater-Pauling. From the study of the thermoelectric properties consisting in plotting curves of different parameters such as: the Seebeck coefficient (S), electrical conductivity per relaxation time (σ/τ), the electronic thermal conductivity per relaxation time ( /τ)  and the merit factor (ZT) as a function of temperature, based on the GGA+U approximation, which is most suitable for the study of this compound, it emerges that the double pérovskite Ba2GdReO6 presents thermoelectric performances in medium to high temperature ranges, in view of the high values ​​of the Seebeck coefficient and those of the electrical conductivity as well as a value close to unity for the merit factor, therefore, this compound can be used for thermoelectric applications in this range of temperatures (medium to high).