Pr_2Fe_(17-x)Al_x系列化合物的结构与磁熵变

Structure and Magnetic Entropy Changes of Pr_2Fe_(17-x)Al_x Compounds

采用熔炼法制备了Pr2Fe17-xAlx系列化合物。利用X射线衍射和MPMS XL-7型磁强计对样品相结构和磁熵变进行了研究。结果表明:Pr2Fe17-xAlx系化合物保持了Th2Zn17型菱方结构,其居里温度可通过成分微调达到室温附近;Pr2Fe17-xAlx系化合物在居里点附近发生的相变属于二级相变,并在较宽温区范围内保持了较大的磁熵变。该化合物在2.0 T外场下的最大磁熵变达到纯金属Gd的60%左右,且其化学性质稳定,制冷温区宽,价格低,是一类具有较大应用潜力的新型室温磁制冷工质材料。

A series of Pr2Fe17-xAlx alloys were prepared by the arc melting. The structure and magnetic entropy changes in Pr2Fe17-xAlx compounds were investigated by X-ray diffractometer and MPMS XL-7 magnetometer. The experimental results show that the crystal structure of Pr2Fe17-xAlx compounds keeps in Th2Zn17-type rhombohedral, and the Curie temperature of Pr2Fe17-xAlx alloys can be shifted to nearly room temperature by a composition adjustment. The phase transition near Curie temperature of the Pr2Fe17-xAlxcompounds belongs to the second order one which conduces large magnetic entropy changes of the compounds in a comparatively wide range of temperature. The maximal magnetic entropy changes of Pr2Fe17-xAlx compounds are about 60% of the pure metal Gd in the external magnetic field of 2 T. Pr2Fe17-xAlx compounds are the potential working media for magnetic refrigeration with their stable chemical properties, wide temperature range for magnetic refrigeration and especially low price.