Abstract Approaching practical thermoelectric devices require high-performance and machinable thermoelectric materials. However, the currently available materials are usually brittle. In this work, Nd-doped Mg3Sb2-based compounds exhibit not only excellent thermoelectric performance but also superior machinability. Mg3.2Nd0.03Sb1.5Bi0.5 exhibits a high power factor of 20.6 μW cm-1 K-2 at 725 K and a peak zT of 1.8, which mainly originates from the increased n of ∼8 × 1019 cm-3 by Nd/Mg substitutional defects. Defect calculations predict that other rare earth elements (Sm, Gd, Tb, Dy and Ho) have the same effect as Nd on Mg3Sb2 and the predicted highest achievable electron concentrations at 700 K are ∼1020 cm-3. The measured hardness, Young’s modulus and fracture toughness of Mg3.2Nd0.03Sb1.5Bi0.5 are 1.1 GPa, 49.8 GPa and 1.4 MPa m1/2, respectively. In addition, the sample can be easily machined into the dog-bone shape with external thread at both ends, indicating the excellent machinability of Mg3Sb2-based materials. This work suggests a bright future of Mg3Sb2-based thermoelectric materials for practical applications and device fabrication.

中文翻译：

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n 型 Mg3Sb2 基材料的点缺陷工程和可加工性

摘要 接近实用的热电器件需要高性能和可加工的热电材料。然而，目前可用的材料通常很脆。在这项工作中，Nd 掺杂的 Mg3Sb2 基化合物不仅表现出优异的热电性能，而且还具有优异的可加工性。Mg3.2Nd0.03Sb1.5Bi0.5 在 725 K 时表现出 20.6 μW cm-1 K-2 的高功率因数和 1.8 的峰值 zT，这主要源于 Nd 使 n 增加了 ~8 × 1019 cm-3 /Mg 置换缺陷。缺陷计算预测其他稀土元素（Sm、Gd、Tb、Dy 和 Ho）对 Mg3Sb2 具有与 Nd 相同的影响，并且预测在 700 K 时可达到的最高电子浓度为 ~1020 cm-3。Mg3.2Nd0.03Sb1.5Bi0.5的实测硬度、杨氏模量和断裂韧性分别为1.1 GPa、49.8 GPa和1.4 MPa m1/2，分别。此外，样品可以很容易地加工成两端带有外螺纹的狗骨形状，表明Mg3Sb2基材料具有优异的可加工性。这项工作表明基于 Mg3Sb2 的热电材料在实际应用和器件制造方面的前景广阔。