(Nd_(1-x)Er_x)_2Co_(15.5)V_(1.5)的结构转变与磁性

Structure transition and magnetic properties of (Nd_(1-x)Er_x)_2Co_(15.5)V_(1.5) compounds

利用电弧熔炼制备了 (Nd1 xErx) 2 Co1 5 5V1 5(x=0— 1 0 )化合物样品 .通过x射线衍射分析和磁性测量研究了Er替代Nd2 Co1 5 5V1 5中的Nd时对化合物结构和磁性的影响 .研究结果表明 ,低Er含量 (x <0 4 ) ,化合物为Th2 Zn1 7型结构 ;高Er含量时 (x >0 5 ) ,化合物转变为Th2 Ni1 7结构 ;Er含量为x =0 4和 0 5时 ,两种结构共存 .两种结构的晶胞参数a ,c和晶胞体积V随着Er含量的增加都呈现递减的趋势 .随着Er含量的增加 ,(Nd1 xErx) 2 Co1 5 5V1 5化合物的居里温度和饱和磁化强度都单调下降 .(Nd1 xErx) 2 Co1 5 5V1 5化合物的室温各向异性由低Er含量时的易锥型转变为高Er含量时的易轴型 .x =0— 0 5的化合物在温度升高时发生自旋重取向转变 。

Structure and magnetic properties of (Nd 1 x Er x ) 2Co 15 5 V 1 5 compounds have been investigated by means of x ray diffraction and magnetic measurements. The results obtained show that the (Nd 1 x Er x ) 2Co 15 5 V 1 5 compounds crystallize in the Th 2Zn 17 type structure for lower Er content( x <0 4) and Th 2Ni 17 type structure for higher Er content( x >0 5). The two structures coexist in the samples with x =0 4 and 0 5 The lattice constants a and c , and the unit cell volume V show a decreasing tendency with increasing Er content in both structures. With increasing Er content, at room temperature, the anisotropy of the (Nd 1 x Er x ) 2Co 15 5 V 1 5 compounds changes from the easy cone type for low Er content( x <0 4) to the easy axis type for higher Er content( x >0 5). The spin reorientation transition is observed for the compounds with x =0 0—0 5, and the spin reorientation temperature T sr shows a decreasing tendency with increasing Er content. In addition, the Curie temperature T C and saturation magnetization M s also decrease monotonically with the Er substitution for Nd in (Nd 1 x Er x ) 2Co 15 5 V 1 5 compounds.