使用高分辨率和原位 TEM 揭示热电 La3-xTe4-Ni 复合材料的结构和稳定性,The Journal of Physical Chemistry C

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使用高分辨率和原位 TEM 揭示热电 La3-xTe4-Ni 复合材料的结构和稳定性
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2021-09-16 , DOI: 10.1021/acs.jpcc.1c05317
Melonie P. Thomas ₁ , Ahamed Ullah ₁ , Dean Cheikh ₂ , Ayanthi Thisera ₁ , Manisha De Alwis Goonatilleke ₁ , Sabah Bux ₂ , Beth S. Guiton ₁

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碲化镧 (La _{3– x} Te ₄ ) 是一种高性能的下一代热电材料，在 1273 K ( x = 0.23 ) 下具有1.1的热电无量纲品质因数 ( zT )，在放射性同位素热电发生器中具有潜在的应用。 RTGs) 为美国国家航空航天局 (NASA) 执行的太空任务提供动力。已经表明，当将镍 (Ni) 纳米颗粒夹杂物引入 La _3-_x Te ₄基体时，zT可以增加 30% 。La _3–_x Te ₄之间的相干界面和 Ni 可能是决定 La _{3- x} Te ₄ -Ni 复合材料稳定性和性能的关键因素，但它们的作用和性质尚不清楚。除了热和氧对界面退化机制和动力学的影响之外，确定 La _{3– x} Te ₄ /Ni 界面在深空条件下的稳定性也很重要。在这里，我们展示了 La _{3– x} Te ₄的高分辨率结构表征和外延晶体学关系– Ni 热电复合材料及其在高真空和环境温度条件下的界面，使用透射电子显微镜 (TEM) 和能量色散 X 射线光谱 (EDS)。我们进一步证明了 La _{3– x} Te ₄ /Ni 界面在其工作温度范围 (25–1000 °C) 内的降解和 Ni 扩散，在有氧和无氧存在的情况下，使用原位TEM实时进行。

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Uncovering the Structure and Stability of Thermoelectric La3–xTe4–Ni Composites Using High-Resolution and In Situ TEM

Lanthanum telluride (La_3–xTe₄) is a high-performance, next-generation thermoelectric material with a thermoelectric dimensionless figure of merit (zT) of 1.1 at 1273 K (x = 0.23) and has potential applications in radioisotope thermoelectric generators (RTGs) to power the space missions conducted by National Aeronautics and Space Administration (NASA). It has been shown that the zT can be increased by 30% when nickel (Ni) nanoparticle inclusions are introduced to the La_3–xTe₄ matrix. The coherent interfaces between La_3–xTe₄ and Ni are likely a key factor determining the stability and performance of the La_3–xTe₄–Ni composites, but their role and nature are not well understood. It is important to determine the stability of the La_3–xTe₄/Ni interface in deep-space conditions, in addition to the effect of heat and oxygen on the mechanisms and kinetics of interface degradation. Here, we show the high-resolution structural characterization and the epitaxial crystallographic relationship of La_3–xTe₄–Ni thermoelectric composites and their interfaces at high-vacuum and ambient-temperature conditions using transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). We further demonstrate the La_3–xTe₄/Ni interface degradation and Ni diffusion over its operating temperature range (25–1000 °C), in the presence and absence of oxygen, in real time, using in situ TEM.

更新日期：2021-09-30

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