Universal Relation between Guest Free Space and Lattice Thermal Conductivity Reduction by Anharmonic Rattling in Type-I Clathrates
Universal Relation between Guest Free Space and Lattice Thermal Conductivity Reduction by Anharmonic Rattling in Type-I Clathrates
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DOI：
10.1143/jpsjs.77sa.61
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发表时间：
2008-01
影响因子：
1.7
通讯作者：
S. Kouichirou;Yamamoto Shuhei;A. Marcos;Takabatake Toshiro
中科院分区：
文献类型：
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作者：
S. Kouichirou;Yamamoto Shuhei;A. Marcos;Takabatake Toshiro
从热电笼形化合物研究的早期开始，已经证明这些化合物中热导率的降低与客体离子的振动特性有关。本文报道了含n型载流子的I型Ba 8In 16 Ge 30-xMx（M = Si，Sn）包合物单晶样品中客体振动与晶格热导率κ L的关系。从Mx = Si1.6到Mx = Sn2.2，晶格常数从11.20增加到11.30，增加了1%。这是伴随着从39至35 K的Ba客体离子在四面体笼的局部振动能量的降低，和一个强的抑制κ L，这表明玻璃状的温度依赖性Mx = Sn 2.2。我们进一步证明，在150 K时κ L的降低显示出普遍性行为，并且在所有I型包合物中与用于振动的客体自由空间非常好地成比例，在很大程度上独立于客体或骨架离子。
Since the early days of studies on thermoelectric clathrates it has been evidenced that the lowering of thermal conductivity in these compounds is related to the guest ion's rattling characteristics. Here we report on the relation between the guest vibration and lattice thermal conductivity κ L in single crystalline samples of type-I clathrates Ba 8 In 16 Ge 30- x M x (M = Si, Sn) with n-type carriers. On going from M x = Si 1.6 to M x = Sn 2.2 , the lattice parameter increases by 1% from 11.20 to 11.30 A. This is accompanied by a decrease from 39 to 35 K in the local vibration energy of the Ba guest ions in the tetrakaidecahedron cages, and a strong suppression of κ L , which shows glasslike temperature dependence for M x = Sn 2.2 . We further demonstrate that the lowering of κ L at 150 K shows universality behavior and scales very well with the guest free space for vibration in all type-I clathrates, largely independent of the guest or framework ions.