(Nd_(1-x)Er_x)_3Fe_(25)Cr(4.0)(0≤x≤1.0)化合物的结构与磁性

Structure and magnetic properties of (Nd_(1-x)Er_x)_3Fe_(25)Cr(4.0) compounds 

合成了 (Nd1 -xErx) 3Fe2 5Cr4 . 0 (0≤x≤ 1 .0 )系列化合物并采用x射线衍射和磁测量等手段研究了它们的结构和磁性 .发现当 0≤x≤ 0 . 8时化合物保持Nd3(Fe,Ti) 2 9型结构 ,属于单斜晶系 ,A2 m空间群 ,当 0 8<x≤ 1. 0时 ,化合物形成一种哑铃对Fe Fe无序替代Th2 Ni1 7结构 ,P6 3 mmc空间群 .随着Er含量的增加 ,化合物的居里温度TC 和饱和磁化强度Ms 单调下降 .当x =0时 ,Nd3Fe2 5Cr4 . 0 化合物的易磁化方向非常靠近 [0. 4 0 ]方向 ,仅略微偏离 1∶5结构的基面 ,但随Er含量的增加 ,(Nd1 -xErx) 3Fe2 5Cr4 .0 化合物的易磁化方向从靠近 [0 4 0 ]方向转向靠近 [4 0 2 ]方向 ,同时与1∶5结构的基面所成的倾角也增大 .通过测量交流磁化率发现 ,x =0— 0 .4和x =1. 0的化合物在低温下出现自旋重取向 .在x =0— 0 . 4的化合物中 ,自旋重取向温度Tsr随Er含量增加单调升高 .用高达 13T的磁场测量难磁化方向的磁化曲线发现 ,在 0≤x≤ 0 . 8的化合物中发生了一级磁化过程 (FOMP) ,其临界场Bcr随Er含量的增加而降低 .

Structure and magnetic properties of the (Nd1-xErx)(3)Fe25Cr4.0(x = 0-1.0) compounds have been investigated by means of x-ray diffraction and magnetic measurements. It is found that the compounds with x = 0-0.8 crystallize in Nd-3 (Fe, Ti)(29) type structure, A2/m space group, but those with 0.8 < x <= 1.0 crystallize in a disordered Th2Ni17-type structure, P6(3)/mmc space group. Both the Curie temperature T-c and the saturation magnetization M-s of (Nd1-xErx)(3)Fe25Cr4.0 decrease monotonically with increasing Er content. The easy magnetization direction (EMD) of the Nd3Fe25Cr4.0 compound is close to the 0401 direction at room temperature, but makes a tilted angle with the basal plane of 1 :5 structure. With increasing Er content the EMD changes to much close to the [402] direction and the tilted angle increases. AC susceptibility measurement indicates the appearance of a spin reorientation at low temperatures for the compounds with x = 0-0.4 and x = 1.0, and the spin reorientation temperature T-c increases monotonically as the Er content increases for the compounds with x = 0-0.4. First-order magnetization process (FOMP) is observed in the compounds with 0 <= x <= 0.8 and the critical field B-er of the FOMP decreases with increasing Er content from 6.6T for x = 0 to 2.0T for x = 0.7.