Synthesis and some properties of Ba24-x(Ga,Sn)136 (x ～ 4) type-II clathrates
Synthesis and some properties of Ba24-x(Ga,Sn)136 (x ～ 4) type-II clathrates
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Ba24-x(Ga,Sn)136 (x ~ 4) II型包合物的合成及部分性能
DOI：
10.1016/j.jssc.2020.121540
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发表时间：
2020
影响因子：
3.3
通讯作者：
Koji Akai
中科院分区：
文献类型：
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作者：
Kazuki Kawasaki;Kengo Kishimoto;Hironori Asada;Koji Akai
通过对Na-Ba-Ga-Sn合金锭的快速熔炼，获得了Ba-Ga-Sn Ⅱ型包合物晶体。该笼形物在20个原子和28个原子的笼中具有Ba客体原子，不像先前报道的Ba-Ga-Sn II型笼形物Ba 16 Ga 32 Sn 104，其在28个原子的笼中没有客体原子。该晶体的化学组成为Ba_（20）Ga_（47）Sn_（89），晶格常数为1.6918 nm。我们烧结晶体来测量包合物的热电性能。烧结样品在低温下表现出p型性能。室温（RT）热导率低至5-6 mW cm− 1 K −1。然而，RT载流子迁移率仅为~5 cm 2 V − 1 s −1，这对于具有Ga-Sn框架的II型笼形物来说非常低。这部分是由于烧结样品的孔隙和晶界散射。这种低迁移率也可能与该笼形物的能带结构有关。
We obtained Ba-Ga-Sn type-II clathrate crystals by centrifuging melted Na–Ba-Ga-Sn ingots. This clathrate had Ba guest atoms in both the 20-atom and 28-atom cages, unlike a previously reported Ba-Ga-Sn type-II clathrate, Ba16Ga32Sn104, which had no guest atoms in the 28-atom cages. The chemical composition and lattice constant of this clathrate crystals were Ba20Ga47Sn89and 1.6918 nm, respectively. We sintered the crystals to measure the thermoelectric properties of the clathrate. The sintered samples exhibitedp-type properties at low temperatures. The room-temperature (RT) thermal conductivities were as low as 5–6 mW cm−1K−1. However, the RT carrier mobilities were only ~5 cm2V−1s−1, and these are very low for type-II clathrates with Ga–Sn frameworks. It is partly because the sintered samples suffered from porosity and grain boundary scattering. Such low mobilities may also be associated with the band structure of this clathrate.