Improvement of electronic and thermoelectric properties of the metallic LaS by sodium substitution: From first-principles calculations

Abstract

In this manuscript, the structural, electronic, and thermoelectric properties of Na doped binary LaS have been studied by means of the full-potential augmented plane wave plus local orbital's method. The Wu-Cohen generalized gradient and the Tran-Blaha modified Becke-Johnson (TB-mBJ) approximations have been employed to describe the exchange-correlation potential. Examining the composition effect on the electronic properties, we point out that LaS compound and Na0.25La0.75S alloy have a metallic behavior. On the other hand, both Na0.5La0.5S and Na0.75La0.25S alloys show a semiconductor behavior with direct bandgap equal to 1.26 and 2.8 eV, using the TB-mBJ approximation, respectively. Moreover, the thermoelectric properties of LaS are enhanced, especially for 50% and 75% of Na concentration. Consequently, the estimated ZT value of about 0.75 at room temperature proves that Na doped metal LaS makes it a promising candidate for thermoelectric applications.

Preparation and application of rare earth sulfides

“…如Viennois等 [160] 计算了立方对 称的γ-La 3 X 4 (X=S, Se, Te)化合物的结构稳定性、晶 格动力学、电子和热电性质, 并且预测其在最佳p掺杂 下, 在300和1273 K时, 热电优值将分别达到至少0.25 和1.5, 表明硫化物La 3−y S 4 具有高温热电应用潜力. Mo-hammed等 [161] 通过第一性原理计算研究了Na掺杂二元…”