热电Bi_(0.5)Sb_(1.5)Te_(3)中扩散屏蔽层材料的筛选

Screening metal diffusion barriers for thermoelectric Bi_(0.5)Sb_(1.5)Te_(3)

Bi2Te3基热电发电器件作为低品位余热回收应用中唯一商业化的热电器件,通常使用镍作为电极.Bi2Te3/Ni的界面处常形成镍碲化合物,Bi_(2)Te_(3)基热电器件以及其他热电器件长期服役的稳定性主要取决于热电材料与电极界面处的长期稳定性(尤其是热端),热电材料与电极之间引入扩散屏蔽层在热电器件的转换效率和服役稳定性方面发挥着重要作用.本工作从13种金属中筛选出Ti作为p型Bi_(0.5)Sb_(1.5)Te_(3)热电材料与Ni电极之间的阻挡层材料.由于Ti在Bi_(0.5)Sb_(1.5)Te_(3)中具有低扩散系数和长期界面稳定性,p型Bi_(0.5)Sb_(1.5)Te_(3)/Ti/Ni单腿器件在200 K温差下转换效率大于6%,并且在持续10天的近1900次转换效率测试中未发生衰减.这为制备高效耐用的热电器件提供了一种实用的策略.

As the only commercialized thermoelectric for low-grade waste heat recovery applications,Bi2Te3-based de-vices commonly use nickel as the electrode.The long-term chemical stability of the Bi_(2)Te_(3)/Ni junction,particularly for the hot side,is one of the major concerns for Bi2Te3-based and other thermoelectrics because of the formation of Ni-Te in-termediate compounds.The utilization of diffusion barrier layers has been proven to be an effective solution and the barriers should have both a good chemical inertness and a slow diffusion.In this work,Ti was screened out from 13 metals in total as an effective barrier material between p-type Bi0.5Sb1.5-Te3 thermoelectric materials and Ni electrodes,because of its low diffusion coefficient and long-term interfacial stability.The fabricated p-type Bi_(0.5)Sb_(1.5)Te_(3)/Ti/Ni single-leg devices show a conversion efficiency over 6%,at a temperature dif-ference of 200 K,without observable degradation for 1860 cycles of measurements lasting for 10 days.This study offers a useful strategy for making efficient and durable thermo-electric devices.