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Inhibiting Mg Diffusion and Evaporation by Forming Mg-Rich Reservoir at Grain Boundaries Improves the Thermal Stability of N-Type Mg3Sb2 Thermoelectrics
Small ( IF 13.0 ) Pub Date : 2023-09-01 , DOI: 10.1002/smll.202305670 Yang Geng 1 , Zerong Li 1 , Zehao Lin 1 , Yali Liu 1 , Qiangwen Lai 1 , Xuelian Wu 1 , Lipeng Hu 1 , Fusheng Liu 1 , Yuan Yu 2 , Chaohua Zhang 1
Small ( IF 13.0 ) Pub Date : 2023-09-01 , DOI: 10.1002/smll.202305670 Yang Geng 1 , Zerong Li 1 , Zehao Lin 1 , Yali Liu 1 , Qiangwen Lai 1 , Xuelian Wu 1 , Lipeng Hu 1 , Fusheng Liu 1 , Yuan Yu 2 , Chaohua Zhang 1
Affiliation
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N-type Mg3Sb2-based thermoelectric materials show great promise in power generation due to their mechanical robustness, low cost of Mg, and high figure of merit (ZT) over a wide range of temperatures. However, their poor thermal stability hinders their practical applications. Here, MgB2 is introduced to improve the thermal stability of n-type Mg3Sb2. Enabled by MgB2 decomposition, extra Mg can be released into the matrix for Mg compensation thermodynamically, and secondary phases of Mg─B compounds can kinetically prevent Mg diffusion along grain boundaries. These synergetic effects inhibit the formation of Mg vacancies at elevated temperatures, thereby enhancing the thermal stability of n-type Mg3Sb2. Consequently, the Mg3.05(Sb0.75Bi0.25)1.99Te0.01(MgB2)0.03 sample exhibits negligible variation in thermoelectric performance during the 120-hour continuous measurement at 673 K. Moreover, the ZT of n-type Mg3Sb2 can be maintained by adding MgB2, reaching a high average ZT of ≈1.1 within 300–723 K. An eight-pair Mg3Sb2-GeTe-based thermoelectric device is also fabricated, achieving an energy conversion efficiency of ≈5.7% at a temperature difference of 438 K with good thermal stability. This work paves a new way to enhance the long-term thermal stability of n-type Mg3Sb2-based alloys and other thermoelectrics for practical applications.
中文翻译：
通过在晶界形成富镁储层来抑制镁扩散和蒸发，提高N型Mg3Sb2热电材料的热稳定性
N型Mg 3 Sb 2基热电材料由于其机械强度高、Mg成本低以及在较宽温度范围内的高品质因数( ZT )，在发电方面显示出巨大的前景。然而，它们较差的热稳定性阻碍了它们的实际应用。这里，引入MgB 2以提高n型Mg 3 Sb 2的热稳定性。通过MgB 2分解，额外的Mg可以释放到基体中以进行热力学Mg补偿，并且Mg─B化合物的第二相可以在动力学上阻止Mg沿着晶界扩散。这些协同效应抑制了高温下Mg空位的形成，从而增强了n型Mg 3 Sb 2的热稳定性。因此，Mg 3.05 (Sb 0.75 Bi 0.25 ) 1.99 Te 0.01 (MgB 2 ) 0.03样品在673 K下连续120小时测量期间，热电性能的变化可以忽略不计。此外，n型Mg 3 Sb 2的ZT可以通过添加 MgB 2来维持，在 300–723 K 内达到约 1.1 的高平均ZT 。还制造了八对 Mg 3 Sb 2 -GeTe 基热电器件，在温差438K，热稳定性好。这项工作为提高n型Mg 3 Sb 2基合金和其他热电材料的实际应用的长期热稳定性开辟了新途径。
更新日期：2023-09-01
中文翻译：
通过在晶界形成富镁储层来抑制镁扩散和蒸发，提高N型Mg3Sb2热电材料的热稳定性
N型Mg 3 Sb 2基热电材料由于其机械强度高、Mg成本低以及在较宽温度范围内的高品质因数( ZT )，在发电方面显示出巨大的前景。然而，它们较差的热稳定性阻碍了它们的实际应用。这里，引入MgB 2以提高n型Mg 3 Sb 2的热稳定性。通过MgB 2分解，额外的Mg可以释放到基体中以进行热力学Mg补偿，并且Mg─B化合物的第二相可以在动力学上阻止Mg沿着晶界扩散。这些协同效应抑制了高温下Mg空位的形成，从而增强了n型Mg 3 Sb 2的热稳定性。因此，Mg 3.05 (Sb 0.75 Bi 0.25 ) 1.99 Te 0.01 (MgB 2 ) 0.03样品在673 K下连续120小时测量期间，热电性能的变化可以忽略不计。此外，n型Mg 3 Sb 2的ZT可以通过添加 MgB 2来维持，在 300–723 K 内达到约 1.1 的高平均ZT 。还制造了八对 Mg 3 Sb 2 -GeTe 基热电器件，在温差438K，热稳定性好。这项工作为提高n型Mg 3 Sb 2基合金和其他热电材料的实际应用的长期热稳定性开辟了新途径。
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