黝铜矿基热电材料能带调控及热稳定性研究

Tetrahedrites based thermoelectric materials have recently attracted intensive attention due to their relatively high performance and environmental friendliness, leading to great potential in waste heat recovery. Considering the difficulty in increasing the power factor of tetrahedrites and the lack of evaluation of their thermal stability, we will use transition metal elements to replace Cu in Cu12Sb4S13-xSex solid solutions in this project. The dopants are expected to affect the band structure near Fermi level that has already possessed a high band degeneracy and synchronously improve the power factor and ZT. Based on the acquired composition, the parameters of rapid synthesis will be optimized. Besides, we will take the thermal stability of tetrahedrites into account, making comprehensive evaluation of their thermoelectric performance. The accomplishment of this project is expected to reveal the influence of dopants on the electronic/thermal transport properties of tetrahedrites S-Se solid solutions, realizing the enhancement in both power factor and ZT. The results of this project will demonstrate the change in thermal stability of tetrahedrites with respect to altered synthesis parameters and dopants. We will further reduce the cost of tetrahedrites production while keep their high performance, laying the foundation for the practical application of tetrahedrites based thermoelectric materials in waste heat recovery.

黝铜矿基合金是近年来受到广泛关注的一种具有较高性能，环境友好的热电材料，非常适合在废热回收领域应用。本项目针对黝铜矿合金功率因子难以提升和热稳定性缺乏评估的问题，以黝铜矿合金S-Se固溶体为研究对象，采用过渡金属元素在Cu位置共掺杂的方法，进一步调控能带结构，充分发挥固溶体费米能级附近能带高简并度的优势，实现功率因子和ZT值的同步大幅提升。在获得最优固溶体组分的基础上，选取含特定元素的天然黝铜矿石为部分原料，探索快速、低成本制备方法，优化工艺参数，衡量材料热稳定性，提高黝铜矿基材料的综合热电性能。项目预期将揭示共掺杂对黝铜矿合金S-Se固溶体电、声输运性质的影响规律，大幅度提升功率因子和ZT值；阐明黝铜矿基热电材料快速制备工艺参数与热稳定性的关联规律；提出在保持高热电性能前提下降低生产成本的一体化方案，为黝铜矿基热电材料在废热回收领域的实际应用奠定基础。

黝铜矿基合金组成元素储量丰富、环境友好、具有本征低的晶格热导率，是目前研究较多的热电材料。本项目针对黝铜矿基合金热电优值难以进一步提升的瓶颈以及其特殊的热电输运机制尚不明朗等问题展开研究，取得了以下主要进展：利用黝铜矿特有的脱溶效应在整个温区实现晶格热导率的大幅下降，结合能带工程和相比例调控，最后热电优值达到了预设的1.2左右，完成了项目指标；基于输运系数理论成功的解释了黝铜矿独特电学输运性质的来源是孤对电子引发的晶格畸变，并通过抑制孤对电子实现了平均功率因子的大幅提升，达到了该体系的最大值；基于黝铜矿晶体结构，开发了新型类黝铜矿体系Ag6Ge10P12，证实了该体系优越的电学性能来自于其强各向异性的能带结构。