A Correlative Study of Interfacial Segregation in a Cu-Doped TiNiSn Thermoelectric half-Heusler Alloy.
A Correlative Study of Interfacial Segregation in a Cu-Doped TiNiSn Thermoelectric half-Heusler Alloy.
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DOI：
10.1021/acsaelm.2c00699
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发表时间：
2022-09-27
影响因子：
4.7
通讯作者：
MacLaren, Donald A.
中科院分区：
文献类型：
--
作者：
Halpin, John E.;Jenkins, Benjamin;Moody, Michael P.;Webster, Robert W. H.;Bos, Jan-Willem G.;Bagot, Paul A. J.;MacLaren, Donald A.
关键词：
热电材料的性能取决于它们的原子尺度化学和微观结构细节的性质，如晶界和夹杂物。在这里，整个TiNiCu0.1Sn热电材料的元素分布已被检查在部署原子探针断层扫描（APT）和电子显微镜和光谱学的相关研究。元素绘图和电子衍射揭示了两种不同类型的晶界，要么是拓扑粗糙和曲折的轮廓或更规则和几何。透射电子显微镜的研究表明，Cu掺杂剂偏析在两种晶界类型，归因于挤压过程中从散装热压。几何边界被发现有一定程度的相邻晶粒之间的晶体学的一致性，粗糙的边界装饰与氧化物杂质沉淀。APT被用来研究粗糙晶界的三维特征，并揭示了Cu是作为离散的，细长的纳米沉淀物cosegregating旁边较大的亚化学计量的氧化钛沉淀物。远离晶界，合金的显微组织是相对均匀的，原子探针的结果表明，统计和均匀分布的Cu没有证据偏析晶粒内。挤压表明铜在散装材料中的溶解度极限，具有影响载流子和声子跨晶界传输特性的潜力。这些结果强调了充分理解影响材料功能的化学局部变化的重要性，特别是在晶界处。
The performance of thermoelectric materials depends on both their atomic-scale chemistry and the nature of microstructural details such as grain boundaries and inclusions. Here, the elemental distribution throughout a TiNiCu0.1Sn thermoelectric material has been examined in a correlative study deploying atom-probe tomography (APT) and electron microscopies and spectroscopies. Elemental mapping and electron diffraction reveal two distinct types of grain boundary that are either topologically rough and meandering in profile or more regular and geometric. Transmission electron microscopy studies indicate that the Cu dopant segregates at both grain boundary types, attributed to extrusion from the bulk during hot-pressing. The geometric boundaries are found to have a degree of crystallographic coherence between neighboring grains; the rough boundaries are decorated with oxide impurity precipitates. APT was used to study the three-dimensional character of rough grain boundaries and reveals that Cu is present as discrete, elongated nanoprecipitates cosegregating alongside larger substoichiometric titanium oxide precipitates. Away from the grain boundary, the alloy microstructure is relatively homogeneous, and the atom-probe results suggest a statistical and uniform distribution of Cu with no evidence for segregation within grains. The extrusion suggests a solubility limit for Cu in the bulk material, with the potential to influence carrier and phonon transport properties across grain boundaries. These results underline the importance of fully understanding localized variations in chemistry that influence the functionality of materials, particularly at grain boundaries.
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