Abstract The performance of nanostructured bulk thermoelectric material is shown to be enhanced because of phonon scattering. However, it is well-known that microstructures evolve by thermal aging, and their stability at the operating temperature is of vital importance to the success of the device. Here, we investigate the effect of long-term annealing (up to 8 weeks) on thermoelectric performance and microstructure of a high-efficiency Na-doped multiphase quaternary Pb chalcogenides. A zT of ~1.7–1.9 in the 700–850 K temperature range is achieved at all stages of thermal aging. A redistribution of Na-dopant between phases above ~630 K is believed to explain an increasing electrical resistivity in aged samples. This is balanced by a reduced total thermal conductivity as thermal aging time increases, possibly because of an increased concentration of nanoscale precipitates in samples aged for 8 weeks. Intermediate annealing of nanostructured lead chalcogenides has been shown to be an effective means of preparing thermally stable, high-performance thermoelectric materials. We have also determined the precipitates coarsening rate constant, k, to be 0.0206 μm/h1/3.

中文翻译：

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热老化纳米结构体材料的热电性能——以铅硫属化物为例

摘要 由于声子散射，纳米结构体热电材料的性能得到提高。然而，众所周知，微结构会随着热老化而演变，它们在工作温度下的稳定性对器件的成功至关重要。在这里，我们研究了长期退火（长达 8 周）对高效 Na 掺杂多相四元 Pb 硫属元素化物的热电性能和微观结构的影响。在 700-850 K 温度范围内，在热老化的所有阶段都实现了 ~1.7-1.9 的 zT。据信，超过~630 K 的相间 Na 掺杂剂的重新分布可以解释老化样品中电阻率的增加。随着热老化时间的增加，总热导率降低，从而平衡了这一点，可能是因为老化 8 周的样品中纳米级沉淀物的浓度增加。纳米结构铅硫属化物的中间退火已被证明是制备热稳定、高性能热电材料的有效手段。我们还确定沉淀粗化速率常数 k 为 0.0206 μm/h1/3。