稀土-过渡族化合物磁热效应的物理机理研究

项目名称： 稀土-过渡族化合物磁热效应的物理机理研究

项目编号： No.11274357

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 数理科学和化学

项目作者： 沈保根

作者单位： 中国科学院物理研究所

项目金额： 95万元

中文摘要： 基于磁热效应的磁制冷技术具有广阔的应用前景，深入研究磁热效应的物理机理，对探索大磁热效应的新型磁制冷材料具有重要意义。本项目拟重点研究具有大磁热效应的一级相变体系（例如LaFeSi）在多场诱导下影响相变过程、相变性质的物理因素及其对磁热效应的影响，多场调控下晶格熵变的变化规律，一级相变体系中出现热滞/磁滞的现象及原因，以及探索获得稀土金属间化合物大磁热效应的有效途径。通过本项研究1）清楚多场作用下一级相变材料中相变过程和相变性质以及交换作用、磁化过程、变磁转变等对磁热效应的影响机制；2）清楚不同体系中磁熵变、晶格熵变、电子熵变的贡献，获得改变晶格熵变的方法，实现体系总熵变的共振增强；3）清楚一级相变体系中产生磁滞、热滞的因素，获得克服和抑制材料磁滞、热滞的方法，有效提高磁热效应材料的制冷能力；4）清楚稀土金属间化合物的晶体结构、磁结构、磁相变与磁热效应的关系，合成出新型高性能磁热效应材料。

中文关键词： 磁热效应；熵变；磁相变；磁性；磁结构

英文摘要： The refrigeration technique based on the magnetocaloric effect (MCE) of magnetic materials has prominent advantages over the conventional technique in the sense of its high efficiency and friendly environment. The study on the relative physics problems of magnetocaloric effect will has an important meaning for exploring novel magnetic refrigeration materials with large magnetocaloric effect. In this project, we will investigate the effect of phase transition process induced by multifield (magnetic field, pressure, temperature) on magnetocaloric effect in first-order magnetic transition systems, such as La(Fe,Si)13-based compounds, the rule of change in lattice entropy change induced by multifield, the physics origin of thermal/magnetic hysteresis, the effective way of obtaining large magnetocaloric effect in rare-earth intermetallic compounds. Through our effort in this project, we will (1) understand the influencing mechanisms of phase transition, magnetization process, itinerant electron metamagnetic transition controlled by multifield on magnetocaloric effect in materials with first-order magnetic transition, (2) understand the different contributions of magnetic entropy change, lattice entropy change and electronic entropy change in different magnetocaloric systems, obtain the effective means for changing la

英文关键词： Magnetocaloric effect；Entropy change；Magnetic phase transition；Magnetic property；magnetic structure