La_(0.8)Pr_(0.2)Fe_(13-x)Si_x金属间化合物的晶体结构和磁熵变研究  

Study on the crystal structure and magnetic entropy change properties of La_(0.8)Pr_(0.2)Fe_(13-x)Si_x(x=1.8,2.0) intermetallic compounds

作　　者：李晓伟[1] 李国栋[1] 张常在[1] 尚涛[1] 

机构地区：[1]内蒙古大学物理系稀土材料重点实验室,内蒙古呼和浩特010021

出　　处：《功能材料》2007年第5期724-726,共3页Journal of Functional Materials

基　　金：国家自然科学基金资助项目(50164003)

摘　　要：通过X射线衍射和磁性测量等手段对所制备的金属间化合物La0.8Pr0.2Fe13-xSix（x=1.8,2.0）的结构和磁性进行了研究。结果表明,在1373K温度下,经过5天退火所得的金属间化合物La0.8Pr0.2Fe13-xSix（x=1.8,2.0）晶体均为单相立方NaZn13型结构;另当Si含量由1.8变为2.0时,引发了晶格体积收缩,居里点升高。当x=1.8时,该化合物在居里温度Tc为210K处具有大的磁熵变｜ΔSM｜,在0-1.5T的磁场下｜ΔSM｜max为10.43J/（kg·K）。当x=2.0时,该化合物在居里温度Tc为226K处具有最大的磁熵变｜ΔSM｜,在0-1.5T的磁场下｜ΔSM｜max为5.23J/（kg·K）。大磁熵变来源于Tc处磁化强度的陡峭变化和Tc以上磁场诱发的巡游电子变磁性转变。The crystal structure and magnetic properties of La0. 5 Pr0. 2 Fe13-x Six （x= 1.8,2.0） have been investigated by X-ray powder diffraction and magnetic measurements. X-ray diffraction patterns reveal that the compounds annealed at 1373K for five days remains the single phase of cubic NaZn13-type structure. The substitution of silicon for iron leads to an increase of the Curie temperature and a reduction of the unit-cell volume. The maximum value of ｜△SM｜max about 10.43J/（kg · K） under a field of 1.5T was achieved in the compound with x=1. 8 at its T~ of about 210K. The large ｜△SM｜ was attributed to the sharp change of magnetization at Tc and the field-induced itinerant-electron metamagnetic transition above To.

关 键 词：磁致冷 NaZn13型金属间化合物 磁熵变 变磁转变 

分 类 号：O482.6[理学—固体物理]