Synthesis and first‐principles calculations of the structural and electronic properties of type‐I clathrates Sr8Ga16SnxGe30 − x
Synthesis and first‐principles calculations of the structural and electronic properties of type‐I clathrates Sr8Ga16SnxGe30 − x
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I型包合物Sr8Ga16SnxGe30−x的合成及结构和电子性质的第一性原理计算
DOI：
10.1002/pssb.201147488
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
H. Ruan
中科院分区：
文献类型：
--
作者：
D. Li;L. Fang;S. Deng;K. Kang;W. H. Wei;H. Ruan
在本工作中，我们报告了I型笼形化合物Sr8Ga16SnxGe30 − x（0 ≤ x ≤ 12）的合成。为了研究Sn取代Ge对结构稳定性和电子结构的影响，采用基于密度泛函理论（DFT）的第一性原理方法研究了Sr8Ga16SnxGe30 − x（0 ≤ x ≤ 30）的结构和电子性质.我们发现Sr8Ga16SnxGe30 − x系列的晶格常数随着Sn含量的增加而增加，这与X射线衍射（XRD）结果一致。计算结果表明，Sn取代Ge导致了材料体积模量的变化，结构稳定性下降。发现这些合金都是间接带隙半导体，并且随着Sn含量的增加，带隙从Sr8Ga16Ge30中的约0.36eV减小到Sr8Ga16Sn30中的约0.03eV。带隙的减小归因于Sr客体运动的自由空间的增加，这伴随着客体的低能模式和较大的非谐性。这意味着增加Sn与Ge的比例不仅可以控制材料的电性能，还可以降低其热导率，这表明笼尺寸调节是获得高性能热电（TE）材料的有用手段之一。
In the present work we report on the synthesis of type‐I clathrates Sr8Ga16SnxGe30 − x (0 ≤ x ≤ 12). To find out how the substitution of Sn for Ge affects structural stability and electronic structure, the structural and electronic properties for Sr8Ga16SnxGe30 − x (0 ≤ x ≤ 30) have been investigated by a first‐principles method based on the density‐functional theory (DFT). We found that the lattice constants of Sr8Ga16SnxGe30 − x series increase with increasing Sn content, which is consistent with X‐ray diffraction (XRD) results. Calculations indicate that the substitution of Sn for Ge leads to the change of the bulk modulus and the decrease of stability of the structure. It is found that these alloys are all indirect‐gap semiconductors and the bandgap decreases from about 0.36 eV in Sr8Ga16Ge30 to about 0.03 eV in Sr8Ga16Sn30 with increasing Sn content. The decrease of the bandgap is attributed to the increase of the free space for the Sr guest motion, which is accompanied by the guest's low‐energy modes and larger anharmonicity. These mean that an increase in the ratio of Sn‐to‐Ge can not only control the electrical properties of the materials, but also may reduce their thermal conductivity, suggesting that cage‐size tuning is one of the useful means to obtain high‐performance thermoelectric (TE) materials.
影响因子：
4
作者：
Avila, M. A.;Suekuni, K.;Takabatake, T.
通讯作者：
Takabatake, T.
影响因子：
3.7
作者：
Suekuni, K.;Avila, M. A.;Takabatake, T.
通讯作者：
Takabatake, T.
影响因子：
3.7
作者：
M. Kozina;F. Bridges;Y. Jiang;M. Avila;K. Suekuni;T. Takabatake
通讯作者：
M. Kozina;F. Bridges;Y. Jiang;M. Avila;K. Suekuni;T. Takabatake