Carrier mobilities, thermoelectric properties, and band structures of type-I clathrates Ba8M16Ge30 (M = Al, Ga, In)
Carrier mobilities, thermoelectric properties, and band structures of type-I clathrates Ba8M16Ge30 (M = Al, Ga, In)
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DOI：
10.35848/1347-4065/aba32a
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发表时间：
2020-07
影响因子：
1.5
通讯作者：
K. Kishimoto;K. Akai
中科院分区：
文献类型：
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作者：
K. Kishimoto;K. Akai
载流子迁移率分析和能带结构计算表明，室温附近载流子的主要散射机制不是声学声子散射，而是由于M原子在骨架上的取代而引起的合金无序散射。此外，它是研究是否在笼中的客体原子的拍击运动影响载流子迁移率由于光学声子散射。导带底部的电子密度不存在于骨架周围，而是存在于客体和骨架原子之间，并且由于取代原子的无序放置而具有各向异性。带隙能量强烈依赖于取代原子的存在。然而，这些特征并不随取代的III族元素的种类而变化很大。M = Al、Ga和In的最大无量纲优值ZT分别为0.65（940 K）、0.74（890 K）和0.51（800 K），这取决于实验获得的载流子浓度。
Analysis of the carrier mobilities and band structure calculations for the titled clathrates indicate that the primary carrier scattering mechanism around room-temperature is not acoustic phonon scattering but alloy disorder scattering due to substituting M atoms on the frameworks. Also, it is studied whether the rattling motion of the guest atoms in the cages affects carrier mobility due to optical phonon scattering. Electron densities of conduction-band bottoms exist not around the frameworks but between the guest and framework atoms and are anisotropic because of disordered placements of substituting atoms. Band-gap energies depend strongly on the presence of the substituting atoms. However, these features do not vary with the kind of substituting group-III elements very much. The maximum dimensionless figure-of-merits ZT were 0.65 at 940 K, 0.74 at 890 K, and 0.51 at 800 K for M = Al, Ga, and In, respectively, which depended on the experimentally achieved carrier concentrations.