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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Layered germanium tin antimony tellurides: element distribution, nanostructures and thermoelectric properties
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Layered germanium tin antimony tellurides: element distribution, nanostructures and thermoelectric properties

机译：层状碲化锗锡锑：元素分布，纳米结构和热电性能

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In the system Ge–Sn–Sb–Te, there is a complete solid solution series between GeSb_2Te_4 and SnSb_2Te_4. As Sn_2Sb_2Te_5 does not exist, Sn can only partially replace Ge in Ge_2Sb_2Te_5; samples with 75% or more Sn are not homogeneous. The joint refinement of high-resolution synchrotron data measured at the K-absorption edges of Sn, Sb and Te combined with data measured at off-edge wavelengths unambiguously yields the element distribution in 21R-Ge_(0.6)Sn_(0.4)Sb_2Te_4 and 9P-Ge_(1.3)Sn_(0.7)Sb_2Te_5. In both cases, Sb predominantly concentrates on the position near the van der Waals gaps between distorted rocksalt-type slabs whereas Ge prefers the position in the middle of the slabs. No significant antisite disorder is present. Comparable trends can be found in related compounds; they are due to the single-side coordination of the Te atoms at the van der Waals gap, which can be compensated more effectively by Sb~(3+) due to its higher charge in comparison to Ge~(2+). The structure model of 21R-Ge_(0.6)Sn_(0.4)Sb_2Te_4 was confirmed by high-resolution electron microscopy and electron diffraction. In contrast, electron diffraction patterns of 9P-Ge_(1.3)Sn_(0.7)Sb_2Te_5 reveal a significant extent of stacking disorder as evidenced by diffuse streaks along the stacking direction. The Seebeck coefficient is unaffected by the Sn substitution but the thermal conductivity drops by a factor of 2 which results in a thermoelectric figure of merit ZT = ～0.25 at 450 °C for both Ge_(0.6)Sn_(0.4)Sb_2Te_4 and Ge_(1.3)Sn_(0.7)Sb_2Te_5, which is higher than ～0.20 for unsubstituted stable layered Ge–Sb–Te compounds.
机译：在系统Ge–Sn–Sb–Te中，GeSb_2Te_4和SnSb_2Te_4之间有完整的固溶系列。由于不存在Sn_2Sb_2Te_5，因此Sn只能部分替代Ge_2Sb_2Te_5中的Ge; Sn含量达75％或更高的样品不是均匀的。对在Sn，Sb和Te的K吸收边缘处测得的高分辨率同步加速器数据与在非边缘波长处测得的数据进行联合优化，可以清楚地得出21R-Ge_（0.6）Sn_（0.4）Sb_2Te_4和9P中的元素分布-Ge_（1.3）Sn_（0.7）Sb_2Te_5。在这两种情况下，Sb都主要集中在扭曲的岩盐型板之间的范德华斯间隙附近的位置，而Ge则更喜欢在板中间的位置。没有明显的抗位紊乱。在相关化合物中可以找到可比的趋势。它们是由于Te原子在范德华间隙处的单面配位，由于其电荷比Ge〜（2+）高，因此Sb〜（3+）可以更有效地补偿。通过高分辨率电子显微镜和电子衍射证实了21R-Ge_（0.6）Sn_（0.4）Sb_2Te_4的结构模型。相比之下，9P-Ge_（1.3）Sn_（0.7）Sb_2Te_5的电子衍射图谱显示出很大程度的堆叠无序，如沿堆叠方向的扩散条纹所证明的。塞贝克系数不受锡取代的影响，但是热导率下降了2倍，这导致Ge_（0.6）Sn_（0.4）Sb_2Te_4和Ge_（1.3）的热电性能因数ZT =〜0.25在450°C ）Sn_（0.7）Sb_2Te_5，对于未取代的稳定层状Ge–Sb–Te化合物，其约为〜0.20。

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