纳米孪晶基元序构的高强度Bi2Te3基热电材料理论设计

Bi2Te3基合金是室温域最好的高性能热电材料之一，但其强度极低，导致材料机械加工性能差，极大限制了材料在物联网、可穿戴装备等微小温差发电领域的重要应用。本项目以发展高强度Bi2Te3基热电材料为目标，以申请者团队发现的通过引入纳米孪晶功能基元可3倍提高Bi2Te3材料理论强度为突破口，构造高强度Bi2Te3基热电材料的纳米孪晶功能基元，研究并阐明纳米孪晶功能基元的本征特性及其与材料力学性能间的构效关系；研究纳米孪晶基元序构（纳米孪晶取向、厚度）在应力场作用下的演化规律和纳米孪晶基元序构引起的相互关联效应及其对材料力学性能的影响，揭示纳米孪晶基元序构影响宏观力学性能的物理机制，构建高强度Bi2Te3基热电材料的纳米孪晶基元序构设计准则；在此基础上，发展纳米孪晶基元序构导致的变革性高强度Bi2Te3基材料的设计理论和方法，为该材料在微型热电器件和可穿戴装备等领域的应用提供理论支撑。

Bi2Te3 based alloy is one of the best high performance thermoelectric (TE) materials in the room temperature range. However, the mechanical strength of Bi2Te3 based TE materials is extremely low, leading to the poor machinability, which largely limits their important small-size TE power generation applications in the field of Internet of Things and wearable devices. This project aims to develop high-strength Bi2Te3 based TE materials. Based on our previous breakthrough showing that introduction of nanotwins can enhance the theoretical strength of Bi2Te3 TE material by 3 times, we will construct the high-strength nanotwin functional units, and illustrate the intrinsic characteristics of nanotwin units as well as their effects on the mechanical properties of Bi2Te3 based TE materials. We will clarify the evolution process of ordered nanotwins units (like nanotwin orientation, thickness) under different stress field and the correlation effect between these ordered structures, as well as their influences on mechanical properties of Bi2Te3 based TE materials. Then, we will reveal the underlying physical mechanism of how ordered structures with nanotwin units influence the macroscopic mechanical properties of Bi2Te3 based TE materials, hence determining the design criteria of ordered nanotwin units with strengthening effect. Finally, we will develop the design theory and method of the unexceptional high-strength Bi2Te3 based TE materials caused by the ordered structures with nanotwin units, which provides the theoretical support for the application of this material in the fields of micro TE devices and wearable devices.