Fe/Bi0.5Sb1.5Te3热电元件高温稳定性研究

热电元件的界面高温稳定性是决定热电器件服役性能和应用前景的重要因素, 而阻挡层和热电材料之间的界面扩散和界面电阻则是评价热电元件高温稳定性的主要标准。为了进一步提升P型碲化铋热电器件的界面稳定性, 本研究采用高通量筛选的方法选定适用于P型碲化铋的Fe阻挡层材料。通过一步烧结的方法制备了Fe/P-BT的热电元件, 并系统研究了高温加速老化实验下的Fe/P-BT的界面微观结构的演变和界面电阻率的稳定性。在老化过程中, Fe/P-BT的界面连接良好且Fe-Sb-Te的三元扩散层的成分基本不变。扩散层厚度与时间的平方根成线性关系, 生长激活能为199.6 kJ/mol。Fe/P-BT的界面电阻率较小且随着老化时间延长缓慢增大, 在350 ℃老化16 d后仍然低于10 μΩ·cm²。基于界面扩散动力学的寿命预测表明Fe可以用作Bi_0.5Sb_1.5Te₃热电元件的阻挡层材料。

High Temperature Interfacial Stability of Fe/Bi0.5Sb1.5Te3 Thermoelectric Elements

The high temperature interfacial stability of thermoelectric(TE)elements,which is mainly evaluated by the inter-diffusion and interfacial resistivity at the interface between the barrier layer and the TE material,is one of the key factors determining the service performance and application prospects of TE devices.In this study,a screening method based on high-throughput strategy was employed to further improve the interfacial stability of P-type bismuth telluride TE devices,and Fe was proved the preferred barrier layer material for P-type Bi_0.5Sb_1.5Te₃(P-BT).Then Fe/P-BT TE elements were prepared by one-step sintering.Evolution of the Fe/P-BT interfacial microstructure during high temperature accelerated aging was systematically studied,and stability of the interfacial resistivity was explored.It is found that during aging,the Fe/P-BT interface is well bonded and the composition of the ternary Fe-Sb-Te diffusion layer remains basically unchanged.The diffusion layer thickness increases linearly with the square root of the aging time and the growth activation energy is 199.6 kJ/mol.The initially low interfacial resistivity of the Fe/P-BT interface increases slowly with the prolonged aging time but remains below 10μΩ·cm² even after 16 d at 350℃.The life prediction based on the interfacial diffusion kinetics indicates that Fe is a suitable barrier layer material for Bi_0.5Sb_1.5Te₃ TE elements.