BiTe-based bulk materials are the best commercially available thermoelectric materials for near room temperature applications. However, the poor mechanical properties of zone melting material and inferior thermoelectric performance of powder metallurgical material restrict their large scale deployment. In this study, -type Bi₂Te₃-based materials were prepared using the hot extrusion technique, and the underlying mechanisms for microstructure evolution were revealed. The hot extrusion speed significantly impacts the strain rate, an indicator to modulate the dynamic recrystallization (DRX) and grain growth, thereby effectively regulating the microstructures of samples. For the sample extruded at a speed of 1.0 mm min, the refined grain with an average grain size of 1.53 μm and an orientation factor of 0.28 is achieved. This highly textured structure and high-density low-angle boundaries (LAGBs) maintain the high carrier mobility of 264 cm V s, comparable with the zone melting sample. In contrast, increasing grain boundaries, dislocations, and inherent point defects intensifies the phonon scattering and suppresses the lattice thermal conductivity to 0.73 W m K. All these contribute to a practical high value of 1.1 at room temperature. Moreover, the fine grains and high-density dislocations ensure robust mechanic properties with a compressive strength of 189 MPa and a bending strength of 139 MPa, which is a guarantee for the successful cutting of microparticles with dimensions of 100 × 100 × 200 μm. The fabrication of high-quality materials with both high thermoelectric performance and strong mechanical properties paves the way for the miniaturization of thermoelectric modules.

中文翻译：

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p 型 Bi2Te3 基化合物的动态再结晶调节可实现高热电性能和稳健的机械性能


BiTe 基散装材料是适合近室温应用的最佳商用热电材料。然而，区域熔炼材料的机械性能较差，粉末冶金材料的热电性能较差，限制了其大规模推广。在这项研究中，使用热挤压技术制备了 型 Bi2Te3 基材料，并揭示了微观结构演变的潜在机制。热挤压速度显着影响应变率，应变率是调节动态再结晶（DRX）和晶粒长大的指标，从而有效调节样品的微观结构。对于以1.0mm·min的速度挤压的样品，获得了平均晶粒尺寸为1.53μm、取向因子为0.28的细化晶粒。这种高度纹理化的结构和高密度小角度边界 (LAGB) 保持了 264 cm V s 的高载流子迁移率，与区域熔化样品相当。相反，增加晶界、位错和固有点缺陷会加剧声子散射，并将晶格热导率抑制至 0.73 W m K。所有这些都有助于在室温下达到 1.1 的实际高值。此外，细晶粒和高密度位错确保了强大的机械性能，抗压强度为189 MPa，弯曲强度为139 MPa，这是成功切割尺寸为100 × 100 × 200 μm的微粒的保证。制造兼具高热电性能和强机械性能的高质量材料，为热电模块的小型化铺平了道路。