PbTe基热电接头界面性能

Interface performance of PbTe-based thermoelectric joints

PbTe具有极高的热电转化效率,本文以获得高质量、高转化效率的PbTe热电接头为目标.Pb的过量可以提高载流子浓度,进而提高PbTe的热电性能,复合电极能够改善界面势垒,降低接触电阻.传统方法通过抑制元素扩散降低接触电阻与提升剪切强度存在矛盾,本文通过引入复合电极,在电极材料与热电材料之间形成中间层,抑制PbTe一侧Pb元素的扩散,在降低接触电阻的同时提高了剪切强度.通过调整PbTe的化学计量比,得到样品Pb50.01Te49.99,在Fe电极中混入Te和Pb,将其与Pb50.01Te49.99一步热压烧结,获得所需要的PbTe热电电极接头.研究结果表明,复合电极的接触电阻与纯Fe连接的相比,接触电阻有近75%的降低,为26.61μΩ·cm^2,更加接近文献报道的最低值10μΩ·cm^2,同时剪切强度相比于纯Fe电极也有较大幅度的提升,这为获得性能优良的PbTe热电接头提供了新思路.

The conversion efficiency of thermoelectric material PbTe is high.A high-quality and high-conversionefficiency PbTe thermoelectric connector is investigated systematically.Excess Pb in composition can increase the carrier concentration and improve the thermoelectric performance of PbTe.The composite electrode can improve the interface barrier and reduce the contact resistance.Traditional processes of making contacts onto bulk crystalline PbTe-based materials do not work for reducing the contact resistance by inhibiting element diffusion and increasing the shear strength at the same time.In this study,we consider a composite electrode which can form an intermediate layer to suppress the diffusion of the Pb element on the PbTe side.This work not only reduces the contact resistance,but also increases the shear strength.The sample Pb50.01Te49.99 is obtained by adjusting the stoichiometric ratio of PbTe;Te and Pb are mixed in the Fe electrode.The composite electrode and Pb50.01Te49.99 are hot-pressed and sintered in one step to obtain the required PbTe thermoelectric electrode joint.We find that the contact resistance of the composite electrode is reduced by nearly 75%compared with that of metallization layer(Fe)connection.The smallest value is 26.610μΩ·cm^2 which is closer to the lowest 10μΩ·cm^2 reported in the literature than the counterpart of pure Fe electrode,and the shear strength is also greatly improved simultaneously.This work provides a new idea for obtaining PbTe thermoelectric connectors with excellent performance.