硫族层状热电材料辐照缺陷对热电性能影响机制研究

Thermoelectric material is widely used in radioisotope thermoelectric generators (RTG) and space nuclear reactor power. Sulphur-layered compound, which is a novel thermoelectric material with great thermoelectric properties, can improve the thermoelectric efficiency of RTG and space nuclear reactor power. RTG and space nuclear reactor release heat as well as neutron，which will result in neutron irradiation damage of thermoelectric material and reducing of carriers’ transport characteristics. The increasing of the point defects and defect groups in the crystal would have great effect on the thermoelectric properties of the materials. Recent studies of Sulphur-layered thermoelectric material mainly focus on improving the thermoelectric properties through band engineering, while there is few study on the irradiation properties. In this project, neutron irradiation effect of typical Sulphur-layered thermoelectric material stannic selenide (SnSe) will be studied using high resolution scanning electron microscopy combined with X-ray diffraction technology, while high intensity D-T fusion neutron generator as neutron irradiation resource, to study the formation of defect generation, the structure evolution and the corresponding thermoelectric properties. This study is expected to reveal the irradiation parameters-defect structure-thermoelectric properties relation, specify the reference irradiation damage threshold of SnSe, put forward the mechanism of irradiation defects influence on the thermoelectric properties of SnSe, and provide data for thermoelectric properties prediction and anti-irradiation design of thermoelectric generator under real irradiation environment.

热电材料被广泛应用于同位素温差发电器（RTG）及核反应堆电源。硫族层状化合物具有优异的热电性能，是最有发展潜力的热电材料，有望显著提高其热电转换效率。RTG和反应堆运行时释放中子，在热电材料晶体结构内部产生点缺陷或者缺陷簇，影响载流子输运特性，使材料热电性能发生退化。现有硫族层状热电材料研究主要集中在通过能带工程提高热电性能，缺少对材料的中子辐照性能研究。本项目以典型硫族层状热电材料硒化锡（SnSe）为研究对象，采用高能中子源实验装置为中子辐照源，利用高分辨扫描透射电子显微技术结合X射线衍射技术，研究SnSe材料中晶体辐照缺陷的产生和结构演变规律，通过测量其宏观热电性能，建立辐照参数-缺陷结构-热电性能的对应关系，提出SnSe材料中子辐照缺陷对热电性能的影响机制，同时明确SnSe热电性能参考中子辐照损伤阈值，为预测真实辐照服役条件下材料的热电性能及热电器件抗辐照性能设计提供依据。

热电材料被可应用于同位素温差发电器（RTG）及核反应堆电源。RTG和反应堆运行时释放中子，在热电材料晶体结构内部产生点缺陷或者缺陷簇，影响载流子输运特性，材料热电性能可能发生退化。硒化锡基热电材料具良好的热电性能，现有材料研究主要集中在热电性能提升研究，对材料的中子辐照性能研究较少。本项目开展硒化锡基热电材料研制和辐照性能研究,基于真空熔炼法，通过多掺杂方法优化热电输运性能，研制具备工程应用价值的硒化锡基热电材料。利用项目承担单位自研的大型强流氘氚聚变中子源HINEG对材料进行长周期中子辐照实验，对辐照前后材料的微观特性和热导率、电导率、塞贝克系数等热电性能进行对比分析。研究表明：硒化锡材料具有良好的辐照稳定性，累计中子辐照剂量约1014n/cm2条件下，辐照前后晶体的电导率、塞贝克系数、导热率和热电优值等热电性能与辐照前相比基本没有变化，证明硒化锡基热电材料的RTG及核反应堆电源应用可行性。相关研究已在 SCI/EI等国内外相关杂志发表论文 4篇，公开发明专利1项；受本基金资助培养硕士研究生2 名。