GeTe-based compounds have been intensively studied recently due to their superior thermoelectric performance, but their real applications are still limited so far due to the drastic volume variation that occurs during the rhombohedral–cubic phase transition, which may break the material or the material/electrode interface during service. Here, superior performance and high service stability for GeTe-based thermoelectric compounds are achieved by co-doping Mg and Sb into GeTe. The linear coefficient of thermal expansion before phase transition is greatly improved to match that after phase transition, yielding smooth volume variation around the phase transition temperature. Likewise, co-doping (Mg, Sb) in GeTe successfully tunes the carrier concentration to the optimal range and effectively suppresses the lattice thermal conductivity. A peak zT of 1.84 at 800 K and an average zT of 1.2 in 300–800 K have been achieved in Ge_0.85Mg_0.05Sb_0.1Te. Finally, a Ni/Ti/Ge_0.85Mg_0.05Sb_0.1Te thermoelectric uni-leg is fabricated and tested, showing quite good service stability even after 450 thermal cycles between 473 K and 800 K. This study will accelerate the application of GeTe-based compounds for power generation in the mid-temperature range.

中文翻译：

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GeTe 基热电化合物的卓越性能和高使用稳定性

GeTe 基化合物由于其优异的热电性能而最近得到了深​​入研究，但由于菱形-立方相变过程中发生的剧烈体积变化，它们的实际应用仍然受到限制，这可能会破坏材料或材料/使用期间的电极接口。在这里，通过将 Mg 和 Sb 共掺杂到 GeTe 中，实现了 GeTe 基热电化合物的卓越性能和高使用稳定性。相变前的线性热膨胀系数大大提高以匹配相变后的热膨胀系数，从而在相变温度附近产生平滑的体积变化。同样，GeTe 中的共掺杂（Mg、Sb）成功地将载流子浓度调整到最佳范围并有效抑制晶格热导率。一个顶峰zT值在800K的1.84，平均的zT 1.2在300-800 K色在葛已经实现_0.85的Mg _0.05锑_0.1碲。最后，制造并测试了 Ni/Ti/Ge _0.85 Mg _0.05 Sb _0.1 Te 热电单腿，即使在 473 K 和 800 K 之间进行 450 次热循环后也显示出相当好的使用稳定性。该研究将加速 GeTe 基的应用用于在中温范围内发电的化合物。