基于同步辐射XAFS低固溶度掺杂SnTe材料的局域原子与电子结构及热电性能调控研究

Developing diversified thermoelectric materials has always been the focus of scientific research. SnTe has the same cubic crystal structure and similar energy band structure as PbTe, which is considered as an ideal lead-free and environment-friendly thermoelectric material to replace PbTe. It has broad application prospects for SnTe materials. Currently, high-performance SnTe thermoelectric materials are mainly focused on high solid-solution-doping, etc. However, it is still a big challenge to realize the improvement of SnTe thermoelectric performance with the same effect under the condition of low cost and low solid-solution-doping. In view of this, this project is based on synchrotron radiation XAFS technology to study the thermoelectric properties, local atomic and electronic structures of a series of low solid-solubility (MgTe, MnTe, CdTe, etc.) doped SnTe systems. By analyzing the doping sites and atomic types of different elements, the parameters of atomic element valence state, empty density of states, coordination number, atomic spacing, disorder degree and the like of each absorption edge will be obtained, so as to compare the bonding mode and strength between the center and coordination atoms. Through theoretical calculation and physical modeling, the band convergence, phonon scattering type and transmission mode of SnTe-doped system will be systematically analyzed. Finally, the intrinsic correlation between local structure, thermoelectric properties and electron-phonon transport intrinsic characteristics is established, which provides new ideas and theoretical guidance for the design and development of high-efficient thermoelectric materials.

开发多元化热电材料一直是科研界关注的焦点，SnTe具有与PbTe相同的立方晶体结构和相似的能带结构，被认为是理想替代PbTe的无铅环保热电材料，应用前景广阔。目前高性能SnTe热电材料主要聚焦在高固溶度掺杂等方面，然而能否在低成本、低固溶度掺杂的情况下实现同等效应SnTe热电性能的提升仍面临较大挑战。鉴于此，本项目基于同步辐射XAFS技术，研究一系列低固溶度(MgTe,MnTe,CdTe等)掺杂SnTe体系的热电性质、局域原子以及电子结构，通过分析不同元素掺杂位点和原子类型，获取各吸收边原子元素价态、空态密度、配位数、原子间距、无序度等参数，从而比较中心与配位原子间的键合模式与强弱。并通过理论计算和物理建模，系统分析SnTe掺杂体系的能带收敛与声子散射类型及传输模式，最终建立局域结构、热电性能、电子-声子输运本征特性之间的内在关联，为设计和开发高效热电材料提供新思路与理论指导。

开发多元化热电材料一直是科研界关注的焦点，SnTe具有与PbTe相同的立方晶体结构和相似的能带结构，被认为是理想替代PbTe的无铅环保热电材料。目前高性能SnTe热电材料主要聚焦在高固溶度掺杂等方面，然而能否在低成本、低固溶度掺杂的情况下实现同等效应SnTe热电性能的提升仍面临较大挑战。鉴于此，本项目系统研究了系列低固溶度掺杂SnTe体系的热电性质、局域原子以及电子结构，并通过理论计算和物理建模，系统分析了SnTe掺杂体系的能带收敛与声子散射类型及传输模式，最终建立了局域结构、热电性能、电子-声子输运本征特性之间的内在关联。此外，本项目还系统对比研究了PbTe、GeTe、Bi2Te3、PbSe、PbS、(SnS)1.2(TiS2)2、AgCrSe2、CoSb3等不同体系的热电材料，为制备高效热电材料与新型器件提供重要支撑。本项目以通讯作者的身份发表标注基金资助的SCI论文35篇，包括Nano Energy、Small、Journal of Materials Chemistry A、Chemical Engineering Journal、Materials Today Physics、Energy Conversion and Management、ACS Applied Materials & Interfaces、Journal of Materials Science & Technology、Applied Physics Letters等，其中影响因子大于19的1篇，大于15的2篇，大于14的3篇，大于11的5篇，大于10的11篇，Nature Index 8篇，授权国内发明专利4项，申请国内发明专利2项，圆满完成项目预期指标和各项任务，取得了较为优秀的研究成果。本项目对加强我国在热电材料领域的国际竞争力，获取自主知识产权和实现碳达峰碳中和均具有重要的现实意义。