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Boron-Mediated Grain Boundary Engineering Enables Simultaneous Improvement of Thermoelectric and Mechanical Properties in N-Type Bi2Te3
Small ( IF 13.0 ) Pub Date : 2021-09-19 , DOI: 10.1002/smll.202104067 Chaohua Zhang 1 , Xingjin Geng 1 , Bin Chen 1 , Junqin Li 1 , Alexander Meledin 2 , Lipeng Hu 1 , Fusheng Liu 1 , Jigui Shi 1 , Joachim Mayer 2, 3 , Matthias Wuttig 4, 5 , Oana Cojocaru-Mirédin 4 , Yuan Yu 4
Small ( IF 13.0 ) Pub Date : 2021-09-19 , DOI: 10.1002/smll.202104067 Chaohua Zhang 1 , Xingjin Geng 1 , Bin Chen 1 , Junqin Li 1 , Alexander Meledin 2 , Lipeng Hu 1 , Fusheng Liu 1 , Jigui Shi 1 , Joachim Mayer 2, 3 , Matthias Wuttig 4, 5 , Oana Cojocaru-Mirédin 4 , Yuan Yu 4
Affiliation
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Powder metallurgy introduces small structures of high-density grain boundaries into Bi2Te3-based alloys, which promises to enhance their mechanical and thermoelectric performance. However, due to the strong donor-like effect induced by the increased surface, Te vacancies form in the powder-metallurgy process. Hence, the as-sintered n-type Bi2Te3-based alloys show a lower figure of merit (ZT) value than their p-type counterparts and the commercial zone-melted (ZM) ingots. Here, boron is added to one-step-sintered n-type Bi2Te3-based alloys to inhibit grain growth and to suppress the donor-like effect, simultaneously improving the mechanical and thermoelectric (TE) performance. Due to the alleviated donor-like effect and the carrier mobility maintained in our n-type Bi2Te2.7Se0.3 alloys upon the addition of boron, the maximum and average ZT values within 298–473 K can be enhanced to 1.03 and 0.91, respectively, which are even slightly higher than that of n-type ZM ingots. Moreover, the addition of boron greatly improves the mechanical strength such as Vickers hardness and compressive strength due to the synergetic effects of Hall-Petch grain-boundary strengthening and boron dispersion strengthening. This facile and cost-effective grain boundary engineering by adding boron facilitates the practical application of Bi2Te3-based alloys and can also be popularized in other thermoelectric materials.
中文翻译：
硼介导的晶界工程能够同时改善 N 型 Bi2Te3 的热电和机械性能
粉末冶金将高密度晶界的小结构引入 Bi 2 Te 3基合金，这有望提高它们的机械和热电性能。然而，由于增加的表面引起的强烈的类施主效应，在粉末冶金过程中形成了 Te 空位。因此，烧结态的 n 型 Bi 2 Te 3基合金显示出比其 p 型对应物和商业区熔 (ZM) 锭更低的品质因数 ( ZT ) 值。这里，硼被添加到一步烧结的 n 型 Bi 2 Te 3基合金抑制晶粒生长并抑制类施主效应，同时提高机械和热电 (TE) 性能。由于在我们的 n 型 Bi 2 Te 2.7 Se 0.3合金中添加硼后减轻的类施主效应和载流子迁移率保持，最大和平均ZT298-473 K 之间的值可以分别提高到 1.03 和 0.91，甚至略高于 n 型 ZM 锭。此外，由于Hall-Petch晶界强化和硼弥散强化的协同作用，硼的加入大大提高了维氏硬度和抗压强度等机械强度。这种通过添加硼实现的简便且具有成本效益的晶界工程促进了 Bi 2 Te 3基合金的实际应用，也可以在其他热电材料中推广。
更新日期：2021-10-21
中文翻译：
硼介导的晶界工程能够同时改善 N 型 Bi2Te3 的热电和机械性能
粉末冶金将高密度晶界的小结构引入 Bi 2 Te 3基合金，这有望提高它们的机械和热电性能。然而，由于增加的表面引起的强烈的类施主效应，在粉末冶金过程中形成了 Te 空位。因此，烧结态的 n 型 Bi 2 Te 3基合金显示出比其 p 型对应物和商业区熔 (ZM) 锭更低的品质因数 ( ZT ) 值。这里，硼被添加到一步烧结的 n 型 Bi 2 Te 3基合金抑制晶粒生长并抑制类施主效应，同时提高机械和热电 (TE) 性能。由于在我们的 n 型 Bi 2 Te 2.7 Se 0.3合金中添加硼后减轻的类施主效应和载流子迁移率保持，最大和平均ZT298-473 K 之间的值可以分别提高到 1.03 和 0.91，甚至略高于 n 型 ZM 锭。此外，由于Hall-Petch晶界强化和硼弥散强化的协同作用，硼的加入大大提高了维氏硬度和抗压强度等机械强度。这种通过添加硼实现的简便且具有成本效益的晶界工程促进了 Bi 2 Te 3基合金的实际应用，也可以在其他热电材料中推广。
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