钴基氧化物热电材料是有着广阔应用前景的一类热电材料。研究发现以Ca3Co4O9基陶瓷为代表的钴基氧化物热电材料热电势的增强起源于运动电荷的自旋，电子自旋熵是引起高热电势的主要原因。本项目借助自旋熵调控研究，探索通过自旋调控优化热电势,并深入研究自旋熵的物理机制。项目拟用4f稀土族离子置换Ca3Co4O9中的Ca位和变价3d过渡金属元素置换Co位相结合的方法，调节Co4+离子浓度和系统原子能级简并度，并可能丰富自旋熵传输途径，探索自旋熵的调控优化。同时通过研究自旋熵传输途径和自旋熵沿Ca3Co4O9单晶不同方向的传输特性，明确自旋熵传输机理；结合声子在自旋熵形成中的作用研究，揭示自旋熵的内在物理机制。通过本项目的研究，掌握调控优化材料自旋熵的有效途径，优化材料的自旋熵和热电势，深化对自旋熵物理机制的认识。本项目对于丰富发展热电基础理论、推动新型高性能氧化物热电材料的研发与应用有重要意义。

The cobalt oxide thermoelectric materials have a good prospect of application. It was proposed that the thermopower of Ca3Co4O9 based cobalt oxide thermoelectric materials originates from spins of moving charge. Spin entropy maybe is the source of its large thermopower. We study on the physical mechanism and manipulation of spin entropy in this project to explore manipulating and optimizing the thermopower through spins. We combine substitution of 4f rare earth ions for Ca with doping of variable valence 3d transition metals into Co sites to manipulate the Co4+ concentration and degeneracy of Ca3Co4O9, also possibly to provide several transport approach for spin entropy for manipulating and optimizing spin entropy. Meanwhile, we can reveal transport mechanism of spin entropy by investigating transport approach of spin entropy and its transport characteristics along different directions in the single crystal. Combining with studying the role of phonon in the formation of spin entropy, we can disclose the physical mechanism of spin entropy. By this project, we can understand the effective ways for manipulating and optimizing the spin entropy. The spin entropy and thermopower of Ca3Co4O9 based oxide thermoelectric materials can be improved and the physical mechanism of spin entropy can be further understood by this study. This project is important to contribute to the thermoelectric theory and to promote research design and application of novel high performance oxide thermoelectric materials.