掺杂诱导Ca9Zn4+xSb9基Zintl相热电材料的结构演变与物性关联机制研究

在Ca9Zn4+xSb9基Zintl相热电材料的Ca位或者Zn位掺杂，掺杂一定量后会伴随材料晶体结构从正交到六方的转变，有效降低晶格热导率，显著提升热电性能。本项目从原子掺杂，晶体结构演变，以及电子结构入手，拓展性的将先进的球差矫正电子显微学技术，与高分辨像衬度分析和图像处理方法相结合，在原子分辨率水平解决Ca9Zn4+xSb9基Zintl相热电材料中与热电优值紧密相关的结构问题，理解该体系中特殊的掺杂效应、反常的电输运调控机制，建立晶体对称性转变和物性之间的关联，澄清结构演变的物理机制。同时改进研究方法，进一步发展和完善图像处理技术，使之有效地应用于Zintl相热电材料中，开创新的应用领域，促进原子分辨电子显微学的发展。

The crystal structure of Ca9Zn4+xSb9 based Zintl thermoelectric materials will change from orthogonal to hexagonal when doped on the Ca sites or Zn sites, which results in reducing the lattice thermal conductivity and significantly improving the thermoelectric performance. In this project, starting from atom doping, crystal structure evolution, and electronic structure, we will use the advanced spherical aberration corrected electron microscopy combined with the high-resolution image contrast analysis and image processing methods to solve the structural problems closely related to the thermoelectric performance enhancement in Ca9Zn4+xSb9 based Zintls at the atomic level, understand the special doping effect and abnormal regulation mechanism of electrical transport in this system, and establish the relationship between the symmetry transition and the physical properties to clarify the physical mechanism of the structural evolution due to different doping. At the same time, we will improve the research methods and further develop the image processing technology, which can be applied to study the Zintl phase thermoelectric materials and promote the development of the atomic-resolution electron microscopy.