晶粒细化是提高Bi_0.5Sb_1.5Te₃合金力学性能的有效途径, 但是粉末冶金过程中晶粒细化导致的类施主效应会严重劣化材料热电性能, 制约了Bi_0.5Sb_1.5Te₃基合金在微型热电器件中的应用。本研究围绕p型Bi_0.5Sb_1.5Te₃基合金, 采用实验结合理论计算系统研究了粉末冶金制备过程中研磨和脱附气氛对烧结样品中类施主效应和电热输运性能的影响规律和机制。Bi_0.5Sb_1.5Te₃基合金破碎研磨过程中粉体表面产生缺陷$~\text{V}_{\text{Te}}^{\cdot \cdot }$和${{\text{{V}'''}}_{\text{Sb}}}$并物理吸附空气中的O₂, 在烧结过程中与吸附的O₂发生缺陷化学反应, 产生大量$\text{V}_{\text{Te}}^{\cdot \cdot }$空位和自由电子, 导致类施主效应, 使空穴浓度大幅降低。在保护气氛下(Ar气氛)研磨避免接触空气或在空气中研磨后放置在保护气氛下脱附O₂, 都可以有效抑制类施主效应, 使样品保持较高的载流子浓度和电导率, 且性能在473 K下保持稳定。在空气中研磨后直接烧结的样品和放置在空气中粉体烧结的样品表现出明显的类施主效应, 样品的载流子浓度从保护气氛处理样品的4.49×10¹⁹ cm⁻³下降至3.21×10¹⁹ cm⁻³, 采用保护气氛处理的粉体烧结样品在402 K下获得最高的热电优值ZT为1.03, 平均ZT_ave为0.92。该研究为调控p型多晶Bi₂Te₃基化合物的类施主效应和优化其热电性能提供了新思路。

Grain refinement is an effective way to improve the mechanical properties of Bi_0.5Sb_1.5Te₃ based alloys. However, the donor-like effect caused by the grain refinement during powder metallurgy severely degrades the thermoelectric properties of the material, which limits the application of Bi_0.5Sb_1.5Te₃-based alloys in micro thermoelectric devices. Therefore, in this study, focusing on p-type Bi_0.5Sb_1.5Te₃-base alloy, the impact of grinding and desorption atmosphere on donor-like effect and thermoelectric transport properties of sintered samples during powder metallurgy process were systematically studied through experiments combined with theoretical calculations. Surface defects $~\text{V}_{\text{Te}}^{\cdot \cdot }$ and ${{\text{{V}'''}}_{\text{Sb}}}$^， generated by the grinding process of Bi_0.5Sb_1.5Te₃-based alloy, reacts with the adsorbed O₂ during sintering process. This generates a large number of $\text{V}_{\text{Te}}^{\cdot \cdot }$ vacancies and free electrons, leading to a donor-like effect and a significant decrease in carrier concentration. The use of protective atmosphere (Ar atmosphere) during grinding to avoid exposure to air or O₂ desorption under protective atmosphere after grinding effectively suppresses the donor-like effect, maintaining high carrier concentration and electrical conductivity of the sample. Moreover, the performance is stable up to 473 K. The samples treated in air or sintered using powder placed in air exhibit a significant donor-like effect, and the carrier concentration decreases from 4.49×10¹⁹ cm^–3 to 3.21×10¹⁹ cm^–3. The maximum thermoelectric ZT of 1.03 is obtained at 402 K for the samples sintered with the powders treated under protective atmosphere, and the overall average ZT_ave reaches 0.92. This study provides a new avenue to regulate the donor-like effect of p-type polycrystalline Bi₂Te₃-based compounds and to optimize their thermoelectric properties.