具有大磁热效应稀土金属间化合物材料研究

The present research choose the rare earth based intermetallics RMn2Si2（R = Er, Pr, Nd and Tm）and RNiBC（R = Gd, Tb, Dy and Ho）compounds as research subject. The crystal structure, magnetic properties, magnetocaloric effect as well as the related physical properties will be systematically studied. Additionally, we will use the elemental substitutin/doping method to modify the crystal structure and magnetic transition temperature of some interesting materials, we will also use the material composite method to improve its relative cooling power. The order of magnetic phase transition (first or second) and the critical exponents as well as its correlation with MCE will be investigated. The origion of giant/large MCE in rare earth based magnetic alloys will be further discussed, these results will give sufficient experimental and theory support for searching new promising materials for magnetic referigeration. The correlation between macro physical properties and micro electronic structure will be clarified based on the experimental results and related theory. The present research may give some new data and theory basis for understanding the underlying physical properties of the rare earth based magnetic materials and searching new rare earth based magnetic functional materials.

本课题在前期发现大磁热效应材料的基础上，选择稀土金属间化合物RMn2Si2（R = Er, Pr, Nd and Tm）体系和RNiBC（R = Gd, Tb, Dy and Ho）体系为研究对象。拟对其晶体结构、磁特性、磁热效应和相关物理特性进行系统研究。将利用元素替代和掺杂的手段有选择的对部分样品的晶体结构、磁相变温度等宏观物理特性进行有效的调控；并利用材料复合的方法提高其磁制冷能力。研究材料的磁相变类型（一级、二级）和临界指数以及其与磁热效应的关联。结合相关理论和实验探讨该类稀土金属间化合物材料中大/巨磁热效应产生的物理机制，为获得高性能磁致冷材料提供实验和理论依据。通过对材料的相关物性的研究，阐明材料的宏观物性与微观电子结构的内在关联，为深入理解稀土磁性合金中存在的一些物理现象和探索新型稀土磁性功能材料提供一些实验和理论依据。

近年来，由于磁性材料的磁热效应在磁制冷领域广阔的应用前景以及其对材料基础物性的反映而引起了物理学家和材料学家的极大关注和兴趣。因此，本课题选择多个代表性的稀土金属间化合物和氧化物体系为研究对象，并利用X射线衍射、扫描电子显微技术和物性测量等实验手段对其晶体结构、微观组织、磁特性和磁热效应进行了以及它们之间的关联进行了系统研究，并在一些材料中发现了优异的磁热性能。另外，本课题结合相关理论和实验讨论了该类稀土化合物材料中大/巨磁热效应产生的物理机制以及该类宏观物性与微观电子结构的关联。本研究可为深入理解稀土化合物材料中存在的一些物理现象和探索高性能磁制冷材料提供一些实验和理论依据。