Grain-by-Grain Compositional Variations and Interstitial Metals-A New Route toward Achieving High Performance in Half-Heusler Thermoelectrics
Grain-by-Grain Compositional Variations and Interstitial Metals-A New Route toward Achieving High Performance in Half-Heusler Thermoelectrics
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DOI：
10.1021/acsami.7b14525
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发表时间：
2018-02-07
影响因子：
9.5
通讯作者：
Bos, Jan-Willem G.
中科院分区：
文献类型：
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作者：
Barczak, Sonia A.;Halpin, John E.;Bos, Jan-Willem G.
基于TiNiSn的Half-Heusler合金具有功率因数大、机械和热稳定性好等优点，是一种很有前途的热电材料，但其导热系数大是制约其发展的瓶颈。已经使用了各种策略来破坏它们的热传输，包括与通常昂贵的重元素和纳米结构形成合金，使得在高温（>773 K）下的品质因数ZT >= 1。在这里，我们展示了一种替代策略，是基于周围的部分偏析过剩的铜导致晶粒的晶粒组成的变化，形成挤出的铜“润湿层”之间的晶粒，和最重要的是，存在的统计上分布的非线性，通过点缺陷散射有效地降低了热导率。我们最好的TiNiCuySn（y
Half-Heusler alloys based on TiNiSn are promising thermoelectric materials characterized by large power factors and good mechanical and thermal stabilities, but they are limited by large thermal conductivities. A variety of strategies have been used to disrupt their thermal transport, including alloying with heavy, generally expensive, elements and nanostructuring, enabling figures of merit, ZT >= 1 at elevated temperatures (>773 K). Here, we demonstrate an alternative strategy that is based around the partial segregation of excess Cu leading to grain-by-grain compositional variations, the formation of extruded Cu "wetting layers" between grains, and-most importantly-the presence of statistically distributed interstitials that reduce the thermal conductivity effectively through point-defect scattering. Our best TiNiCuySn (y