磁一级相变La(Fe,Si)13基化合物的研究进展

对NaZn13型La(Fe,Si)13化合物在磁性、相变特性及磁熵变规律和制备方法等方面的研究进展进行总结和论述.低Si含量的La(Fe,Si)13化合物具有良好的软磁特性,表现出特殊的磁相变特征:在居里温度处的热诱导一级磁性转变和高于居里温度时的磁场诱导巡游电子变磁性转变,并伴随着巨大的磁熵变和磁致伸缩.随Si含量增高,化合物的这种特殊磁相变特征逐渐减弱,呈现二级相变特征.总结了元素替代和添加对La(Fe,Si)13化合物性能的影响,一定的合金化可以改变居里温度并保持巨大的磁熵变,这对于近室温磁致冷有着重要意义.快速凝固技术的应用解决了化合物合成困难的问题,降低了材料的制造成本,使得NaZn13型La(Fe,Si)13化合物成为最有应用前景的近室温磁致冷工质之一.本文还探讨了这种化合物用做磁致伸缩材料的可能性.

Recent Developments in First-order Phase Transition Material of La(Fe,Si)13 Compounds

The progress in research on magnetic properties,phase transition,magnetic entropy change and synthetic method for La(Fe,Si)13 compounds were presented.The La(Fe,Si)13 compounds with low Si are excellent soft magnetic material and exhibit unusual magnetic phase transition: the compounds present a thermal induced first-order magnetic phase transition at the Curie temperature and a field induced itinerant electron metamagnetic transition at higher temperatures.A simultaneous giant magnetic entropy change and magnetostrictive are found.With the increase of the Si content,the characteristic of magnetic phase is typical for a second-order magnetic transition.The Curie temperature TC increase to room temperature and the magnetic entropy change keep very large after alloying.It is very useful for room temperature magnetic refrigerants.The difficulty of synthesis can be solved by melt spinning so that the product cost will be cut significantly.These results suggest that the NaZn13-type La(Fe,Si)13 compounds are promising candidates for room magnetic refrigerant.In addition,the present compounds have a possibility for applications as giant magnetostrictive materials.