Shen Jinni, Xie Tianzhu, Zhang Longkun, Wang Ping, Fang Zhenxing
College of Materials Science and Engineering, Fuzhou University, Fuzhou, 350108, China.
Key Laboratory of Eco-materials Advanced Technology, College of Materials Science and Engineering, Fuzhou University, Fuzhou, 350108, China.
Sci Rep. 2020 Feb 20;10(1):3068. doi: 10.1038/s41598-020-59820-8.
Based on global particle-swarm optimization algorithm and density functional theory methods, we predicted an alloyed SiGe compond with body centered tetragonal type VII clathrate (space group I4/mmm) built by a truncated octahedron fromed by six quadrangles and eight hexagons ([46]). SiGe clathrate is 0.06 eV/atom lower than VII Si clathrate and thermally stable up to 1000 K. It has an indirect band gap of 0.23 eV, high p-doping Seebeck coefficient and n-doping electrical conductivity. It owns a low lattice thermal conductivity of 0.28 W/mK at 300 K because of its weak bonding and strong anharmonic interaction of longitudinal acoustic and low-lying optical phonons. The moderate electronic transport properties together with low lattice thermal conductivity results in a high optimal thermoeletric performance value of 2.54 (1.49) at 800 (1000) K in n (p)-doped SiGe.
基于全局粒子群优化算法和密度泛函理论方法，我们预测了一种合金化的SiGe化合物，它具有体心四方结构的VII型笼形结构（空间群I4/mmm），由六个四边形和八个六边形构成的截顶八面体组成（[46]）。SiGe笼形化合物比VII型Si笼形化合物的原子能量低0.06 eV，热稳定性高达1000 K。它具有0.23 eV的间接带隙、高的p型掺杂塞贝克系数和n型掺杂电导率。由于其键合较弱以及纵向声学声子和低频光学声子的强非谐相互作用，它在300 K时的晶格热导率较低，为0.28 W/mK。适度的电子输运性质与低晶格热导率相结合，使得n（p）型掺杂的SiGe在800（1000）K时具有2.54（1.49）的高最佳热电性能值。
