Mn替代对Dy2AlFe16－xMnx化合物的结构和磁性的影响

通过X射线衍射及磁测量手段研究了Dy₂AlFe_16-xMn_x化 合物的结构和磁性.研究结果表明Dy₂AlFe_16-xMn_x化合 物具有六角相的Th₂Ni₁₇型结构.对x=1，2的样品采用X射线热膨胀 测定法在104—647K的温度范围内测量了其热膨胀性质，发现这些化合物在低温下存在热膨 胀反常现象，在居里点附近出现负膨胀性质.对自发磁致伸缩的研究结果表明Dy₂AlFe_16-xMn_x化合物中存在着较强的各向异性的自发磁致伸缩，随 着Mn含量的增加，其低温下的自发体磁致伸缩减弱.磁测量结果表明Mn的替代导致Dy_{2< /sub>AlFe16-xMnx化合物的居里温度及自发磁化强度急剧下降. 关键词： 2}AlFe_16-xMn_x化合物')" href="#">Dy₂AlFe_16-xMn_x化合物 反常热膨胀 自发磁致伸缩 自发磁化强度

Effect of Mn substitution on the structure and magnetic properties of Dy2AlFe16-x Mnx compounds

The structural and magnetic properties have been investigated by means of X-ray diffraction and magnetization measurements. The Dy₂AlFe_16-xMn_x compounds have a hexagonal Th₂Ni₁₇-type st ructure. The thermal expansion of Dy₂AlFe_16-xMn_x (x=1 and 2) compounds have been investigated by X-ray dilatometry in the tempe rature range 104—647K. The results show that there is a thermal expansion anoma ly at low temperature and a negative thermal expansion near the Curie temperatur e. There exists a strong and anisotropic spontaneous magnetostriction in the mag netic state of Dy₂AlFe_16-xMn_x compounds. The sp ontaneous volume magnetostrictive deformation at low temperature decreases with increasing x. The result of magnetization measurement shows that the Curie tempe rature and the spontaneous magnetization of Dy₂AlFe_16-xMn< sub>x compounds at 5K decrease rapidly with increasing x.