基于磁各向异性的取向多晶磁制冷材料的旋转磁热效应研究

As the new field of magnetic refrigeration research, the “rotating magetocaloric effect (RMCE)” will not only be much helpful to our theoretical understanding on magnetocaloric effect, but also provide new thoughts for the design of magnetic refrigeration materials and machines. However, since the research on RMCE has just started, the physical mechanism is still unclear and most studies are focused on the single crystals, which hinder the development and application of this novel technology. In our upfront work, we found for the first time that the textured polycrystalline DyNiSi and LaMn2Si2 compounds exhibit RMCE. Based on that, this project is proposed to study the RMCE based on magnetic anisotropy in oriented polycrystalline materials. The regulation mechanism on orientation will be investigated by different methods such as directional solidification and magnetic heat treatment. The physical mechanism of RMCE will be studied by combining theoretical and experimental methods. The RMCE will be enhanced by optimizing the composition and processing technique. Consequently, we expect to fully understand the physical and optimization mechanisms of RMCE, and obtain a material design method which could guide us to explore room temperature RMCE materials.

“旋转磁热效应”作为磁制冷研究的新方向，不仅能够丰富我们对磁热效应的理论理解，还能够为磁制冷材料和磁制冷机的设计提供新思路。然而目前对旋转磁热效应的研究刚刚起步，对其物理机理尚不清楚，且多集中于研究磁性单晶体，限制了该技术的发展和应用。在前期探索工作中，我们首次在织构多晶的DyNiSi和 LaMn2Si2材料中发现了旋转磁热效应，在此基础上，本项目创新性的提出了基于磁各向异性的取向多晶材料的旋转磁热效应研究思路。利用定向凝固及磁场热处理等方法研究磁各向异性材料的取向调控机制；通过实验与理论相结合的方法深入研究旋转磁热效应的物理机理；并从成分和工艺优化两方面来研究旋转磁热效应的优化机制。最终阐明旋转磁热效应产生的物理机理，弄清其优化机制，找到获得大旋转磁热效应的材料设计方法，并利用这一设计方法来探索室温新型旋转磁热效应的多晶材料。

“旋转磁热效应”作为磁制冷研究的新方向，不仅能够丰富我们对磁热效应的理论理解，还能够为磁制冷材料和磁制冷机的设计提供新思路。然而目前对旋转磁热效应的研究刚刚起步，对其物理机理尚不清楚，且多集中于研究磁性单晶体，限制了该技术的发展和应用。本项目创新性的提出基于磁各向异性的取向多晶材料的旋转磁热效应研究思路。通过实验和理论相结合的方法，阐明了稀土金属间化合物的磁晶各向异性机理，弄清了相变前后旋转磁热效应的贡献来源，获得了目前报道的最大旋转磁热效应；从成分和工艺优化两方面研究其优化机制，阐明了成分调控对Nd1-xTbxCo5磁各向异性以及旋转磁热效应的优化机理；分析验证了不同旋转磁熵变计算方法的等效性，同时，探索获得了Tb3NiGe2和Ho2GdAl2新型旋转磁热效应材料，有望应用于液化天然气温区的旋转磁制冷技术。本项目的研究成果不仅促进了我们对旋转磁热效应相关物理机制的理解，为进一步深入研究提供了良好的基础。更指导我们获得了新的旋转磁热效应材料，推进了该技术在磁制冷领域的应用。