SiGe alloys exhibit high thermoelectric performance at mid to high temperatures, but their wide applications are hindered by intrinsically high thermal conductivity. Here, we report a new strategy for regenerating ultrafine nano phases of CrSi and SiO with an average grain size of approximate 130 nm by chemical reaction of Si and strong oxidizing CrO in a p-type SiGe matrix. Based on the Debye-Callaway calculation, the nano-sized second phase leads to a reduction in phonon relaxation time, thereby lowering the thermal conductivity to an ultralow value of 2.15 W m K at 873 K. The boundaries between the second phases (CrSi) and the matrix (SiGe) establish potential barriers, allowing carrier filtering and phonon scattering, thus increasing the power factor. Eventually, the sample (CrO)-SiGeB reaches a peak of approximately 1.12 at 873 K, with an average of approximately 0.62 from 323 K to 873 K, representing a 55.56% improvement compared with SiGeB. Our method provides a promising approach for enhancing the thermoelectric performance of SiGe.

中文翻译：

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通过再生 SiGe 中的纳米夹杂物实现声子弛豫效应，实现超低热导率并增强热电性能

SiGe合金在中高温下表现出高热电性能，但其固有的高导热性阻碍了其广泛应用。在此，我们报告了一种通过 Si 与强氧化性 CrO 在 p 型 SiGe 基体中发生化学反应来再生平均晶粒尺寸约为 130 nm 的 CrSi 和 SiO 超细纳米相的新策略。根据Debye-Callaway计算，纳米尺寸的第二相导致声子弛豫时间减少，从而将热导率降低至873 K时2.15 W m K的超低值。第二相（CrSi）之间的边界矩阵（SiGe）建立势垒，允许载流子过滤和声子散射，从而提高功率因数。最终，样品(CrO)-SiGeB在873 K处达到峰值约1.12，从323 K到873 K的平均值约为0.62，与SiGeB相比提高了55.56%。我们的方法为增强 SiGe 的热电性能提供了一种有前景的方法。