球磨制备的La(Fe1-xCox)11.2Si1.8化合物的相形成和磁热效应

Phase Formation and Magnetocaloric Effect in La(Fe1-xCox)11.2Si1.8 Compounds Prepared by Ball-milling

摘要:

将LaSi母合金和元素粉末混合，利用球磨工艺制备了La(Fe1-xCox)11.2Si1.8 (x = 0, 0.02, 0.04, 0.06)样品。在1423K的温度下烧结30分钟，然后放入水中快速冷却，就可以获得几乎为NaZn13型结构的单相化合物。磁性质的研究表明，样品的居里温度随着Co含量从x=0到x=0.06而提高，但是磁熵变减小。在0-1.5T的外加磁场下，LaFe11.2Si1.8合金在其居里温度附近的最大磁熵变达到的6.5 J/kg，而x=0.06的样品的最大磁熵变约为2.1 J/kg K。另外，球磨制备的样品还呈现了二级磁相变的特点，这对于磁热效应的应用非常有意义。

Abstract:

The samples of La(Fe1-xCox)11.2Si1.8 (x = 0, 0.02, 0.04, 0.06) have been prepared by ball-milling with elemental powder and LaSi cast master alloys. After sintering at 1423 K for 30 minutes followed by a quenching in water, an almost NaZn13 type single phase has been obtained. The study of magnetic properties revealed that the Curie temperature increases with Co content from x=0 to 0.06 whereas the magnetic entropy change decreases. The alloy of LaFe11.2Si1.8 has a maximum magnetic entropy change △Sm of 6.5 J/kg K near its Curie temperature under a magnetic field of 0-1.5T, while the maximum magnetic entropy change is about 2.1 J/kg K with x=0.06. Furthermore, the magnetization of ball-milled samples exhibits a second-order magnetic transition, which is interesting for magnetocaloric applications.