塞贝克系数
热电效应
热导率
材料科学
半经典物理学
赝势
物理
电阻率和电导率
反向
热电材料
热力学
凝聚态物理
量子力学
几何学
数学
量子
作者
Xiaojian Tan,W. Liu,H. J. Liu,Jing Shi,Xinfeng Tang,Ctirad Uher
标识
DOI:10.1103/physrevb.85.205212
摘要
The band structure of Mg${}_{2}$Si${}_{1\ensuremath{-}x}$Sn${}_{x}$ solid solutions with 0.250 \ensuremath{\leqslant} $x$ \ensuremath{\leqslant} 0.875 is calculated using the first-principles pseudopotential method. It is found that the low-lying light and heavy conduction bands converge and the effective mass reaches a maximum value near $x$ $=$ 0.625. Using the semiclassical Boltzmann transport theory and relaxation-time approximation, we find that the system with $x$ $=$ 0.625 exhibits both higher Seebeck coefficient and higher electrical conductivity than other solid solutions at intermediate temperatures. By fitting first-principles total energy calculations, a modified Morse potential is constructed, which is used to predicate the lattice thermal conductivity via equilibrium molecular dynamics simulations. Due to relatively higher power factor and lower thermal conductivity, the Mg${}_{2}$Si${}_{0.375}$Sn${}_{0.625}$ is found to exhibit enhanced thermoelectric performance at 800 K, and additional Sb doping is considered in order to make a better comparison with experiment results.
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