Preparation and thermoelectric properties of sintered type-II clathrates (K,Ba)24(Al,Sn)136
Preparation and thermoelectric properties of sintered type-II clathrates (K,Ba)24(Al,Sn)136
复制标题
烧结型II型包合物(K,Ba)24(Al,Sn)136的制备及其热电性能
DOI：
10.1016/j.jallcom.2016.09.231
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发表时间：
2017
影响因子：
6.2
通讯作者：
Tsuyoshi Koyanagi
中科院分区：
文献类型：
--
作者：
Suguru Utsunomiya;Kengo Kishimoto;Shota Koda;Koji Akai;Hironori Asada;Tsuyoshi Koyanagi
k9ba15al38sn98和k9ba15al31ga8sn97烧结样品在590 K和640 K时的最大无因次值分别为0.57和0.82，低于K6Ba18Ga40Sn96的1.17。该包合物骨架中Sn的取代原子对其电子和电学性能有显著影响。与Ga取代相比，Al取代破坏了导带边缘的色散带，导致更大的惯性质量。这种取代也导致烧结样品中缺陷密度增大。结果表明，al取代的烧结样品室温载流子迁移率仅为30-40 cm2V−1s−1，低于ga取代的170 cm2V−1s−1。另一方面，取代原子对热性能的影响不大。al取代的烧结样品晶格热导率较低，为5 mW cm−1K−1，这是由于与ga取代的样品一样具有强烈的咔嗒效应。
The maximum dimensionless figures of merit were 0.57 at 590 K and 0.82 at 640 K for the K9Ba15Al38Sn98and K9Ba15Al31Ga8Sn97sintered samples, respectively, which were lower than that 1.17 of K6Ba18Ga40Sn96. The substituting atom for Sn in the framework of this clathrate affected its electronic and electrical properties significantly. Compared to Ga substitution, Al substitution damaged dispersive bands at the conduction-band edge, resulting in a larger inertial mass. This substitution also caused larger defect densities in the sintered samples. As a result, the Al-substituted sintered samples had room-temperature carrier mobilities of only 30–40 cm2V−1s−1, which were lower than that ∼170 cm2V−1s−1of the Ga-substituted ones. On the other hand, the substituting atom did not influence the thermal properties very much. The Al-substituted sintered samples had as low lattice thermal conductivities as 5 mW cm−1K−1due to a strong rattling effect like the Ga-substituted ones.