Mn替代对Dy_2AlFe_(16-x)Mn_x化合物的结构和磁性的影响

Effect of Mn substitution on the structure and magnetic properties of Dy_2AlFe_(16-x)Mn_x compounds

通过X射线衍射及磁测量手段研究了Dy_2AlFe_(16-x)Mn_x化合物的结构和磁性.研究结果表明Dy_2AlFe_(16-x)Mn_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Dy_2AlFe_(16-x)Mn_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_2AlFe_(16-x)Mn_x化合物的居里温度及自发磁化强度急剧下降.

The structural and magnetic properties have been investigated by means of X-ray diffraction and magnetization measurements. The Dy2AlFe16-x Mnx compounds have a hexagonal Th2Ni17-type structure. The thermal expansion of Dy2AlFe16-xMnx （x = 1 and 2） compounds have been investigated by X-my dilatometry in the temperature range 104--647K. The results show that there is a thermal expansion anomaly at low temperature, and a negative thermal expansion near the Curie temperature. There exists a strong and anisotropie spontaneous magnetostriction in the magnetic state of Dy2AlFe16-x Mnx compounds. The spontaneous volume magnetostrictive deformation at low temperature decreases with increasing x. The result of magnetization measurement shows that the Curie temperature and the spontaneous magnetization of Dy2AlFe16-x Mnx compounds at 5K decrease rapidly with increasing x.