高压相变调控Mg2Si基热电材料微结构及热电性能研究

Thermoelectric materials are new energy materials that can convert electricity and heat. They have high application value in thermoelectric power generation and thermoelectric refrigeration. In this study, the solid solution Mg2Si-based alloy is used as the object, and the high temperature and pressure technologies can be used to control the different high-pressure phases of Mg2Si-based alloys. The evolution behavior and law of microstructure during the subsequent heat treatment are studied, and the new Mg2Si-based alloys under temperature and pressure regulation are discussed. Microscopic mechanism and reversible phase change control phonon scattering center mechanism, revealing the evolution of Mg2Si-based thermoelectric materials such as grains, defects and crystal orientation; and developing high-performance Mg2Si-based alloys through development and preparation techniques and control processes The controllable preparation of the grade structure enriches the basic theory of improving the thermoelectric properties of materials, and expands the preparation technology of high-performance multi-stage thermoelectric materials, providing a new theoretical basis and technical basis for the performance optimization of thermoelectric materials. A new technology for preparing Mg2Si-based alloys with multi-stage structure with high thermoelectric properties should been developed, and the thermoelectric performance control scheme of new Mg2Si-based alloys should been studied. The theory of microstructure evolution of thermoelectric materials should been deepen and enriched to promote the practical application of high-performance thermoelectric materials.

热电材料是一种可以在静态下实现电能和热能之间相互转换的新型能源材料，在温差发电与热电制冷领域具有很高的应用价值。本课题以固溶Mg2Si基合金为对象，通过高温高压技术手段理性可控制备Mg2Si基材料不同高压相，并研究后续热处理过程中的组织结构演化行为与规律，探讨温压调控新型 Mg2Si基合金微观组织机理及可逆相变调控声子散射中心机制，揭示高压制备的Mg2Si基热电材料晶粒、缺陷及晶体取向等演变规律；通过开发制备技术及调控工艺，实现具有高性能的 Mg2Si基合金多级结构的可控制备，丰富提高材料的热电性能的基础理论，拓展高性能多级结构热电材料的制备技术，为热电材料的性能优化提供新的理论依据和技术基础。开发出具有高热电性能的多级结构的Mg2Si基合金制备新技术，进而研究新型Mg2Si基合金热电性能调控方案，深化和丰富热电材料微观组织演变理论，推动高性能热电材料的实际应用。

热电材料是一种可以在静态下实现电能和热能之间相互转换的新型能源材料，在温差发电、热电制冷、催化等领域具有很高的应用价值。本项目以固溶Mg2Si基合金为对象，通过高温高压技术手段成功制备了Sb掺杂的Mg2.05(Si0.6Sn0.4)1-xSbx样品。Sb掺杂Mg2.05(Si0.6Sn0.4)0.98Sb0.02的功率因子在773 K时达到最大值1924.30 μWm-1K-2，636 K时达到了最低热导率1.05 Wm-1K-1，样品在715 K时取得ZT最大值0.94。引入高压相变的Mg2.05(Si0.6Sn0.4)0.98Sb0.02样品在773 K功率因子得到了极大的优化，取得最大值2983.31μWm-1K-2。亚稳Mg2Sn相的固溶在材料中引入了大量的位错和晶格畸变，有利于晶格热导率的进一步降低，在723 K时达到了最低晶格热导率0.42 Wm-1K-2，比未引入相变的Mg2.05(Si0.6Sn0.4)0.98Sb0.02的晶格热导率低了60%。最终其ZT值在773 K时达ZT值1.3，提升了35%。高压相变优化热电材料性能为热电材料的性能优化提供新的理论依据和技术基础。为研究新型具有高压相变结构的热电材料性能优化，深丰富热电材料微观组织演变理论，推动高性能热电材料的实际应用提供新思路。