高性能VIII型Sn基大尺寸单晶笼合物制备及高温稳定性研究

基于Cu掺杂VIII型Sn基单晶笼合物具有较高热电性能，探索布里奇曼法制备高性能大尺寸Cu掺杂Sn基单晶笼合物热电材料，并对其高温结构及性能稳定性进行研究。首先采用第一性原理及分子动力学从理论上研究Cu掺杂对化合物声子谱、电子结构及结构稳定性的影响；其次通过调整坩埚下降速率，生长炉温度场分布，起始原料比等参数制备出具有p和n型传导的Sn基单晶笼合物,采用XRD、Raman，EPMA、FESEM等研究不同制备工艺对材料微结构的影响,进而研究其对材料热电传输特性的影响，结合理论计算结果,优化制备工艺,制备高性能（其中n型材料ZT≥1.4，p型材料ZT≥1.3）Cu掺杂大尺寸单晶笼合物。最后在理论计算的指导下通过实验对材料的高温结构稳定性及相应材料热电特性的演变规律进行研究。本项目对研究和开发高性能中温热电材料及器件，对大规模汽车尾气、工厂余热发电等具有重要意义。

Based on the high thermoelectric performance ZT of Cu-dopped Sn-based type-VIII single crystal clathrate,we will explore to prepare high performance large size type-VIII single crystal clathrate by Bridgeman method, and the study on the high-temperature stability will be carriered out simultaneously.At first, the effect of Cu dopping on the phonon spectrum, electronic structure and high-temperature stability will be calculated by the First Principles and Dolecular Dynamics calculations.Secondly，we will try to prepare p-type and n-type Cu-dopped Sn-based large size single crystal clathrate by Bridgeman method through adjusting the descent speed of crucible，temperature distribution of furnace, and the ratio of starting materials,and the study on the microstructure will be carried out by XRD，Raman，EPMA，FESEM, and so on.Ulteriorly, the effects of the materials' microstructure on the thermoelectric transport properties will be studyed. Based on the theoretical calculations, the Cu-dopped Sn-based type-VIII large size single crystal clathrate with high thermoelectric performance ZT （ZT≥1.4 for n-type conduction，and ZT≥1.3 for p-type conduction）will be prepared by adjusting and optimizing the technique process.At last, under the guidance of theoretical calculations, the high-temperature stability and the evolution rule of thermoelectric properties in the high temperature of the obtained materials will be studyed by the means of experiment. The above study which will be carried out in this project has a vital significance on the research and exploitation of high performance medium-temperature thermoelectric materials and device,on the large-scale automobile exhaust gas power generation，and on the factory waste heat power generation.