稀土磁致冷Gd_5Ge_2(Si_(2-x)Mn_x)化合物的结构及微观机制

The Study of Structure and Micro-mechanism of the Gd_5Ge_2(Si_(2-x)Mn_x)

利用X射线衍射和扫描电镜对Gd5Ge2(Si2-xMnx)结构及表面形貌进行了研究.并利用差示量热法对Gd5Ge2(Si2-xMnx)的磁热性能进行了研究.x射线衍射(XRD)测量分析表明Mn的替代不会影响母体Gd5Si2Ge2的晶体结构,样品中的主相仍然具有单斜结构(P1121/a),其晶体对称性不会随Mn含量的增加而改变.随着Mn含量的增加,晶粒逐渐变大,晶常数增大,体积膨胀,同时Mn和杂质相的析出量也在增加.少量的Mn元素替代Si可以提高Gd5Si2Ge2化合物的居里温度.

The crystal structures and surface morphologies of GdsGe2 （Si2-x Mnx ） were studied by X-ray dif- fraction （XRD）, scanning electron microscope （SEM） and differential scanning calorimetry （DSC） methods etc. All the samples analyzed by XRD are monoclinic structure （ P1121/α ）, and the symmetry has no obvious change with the increase of Mn atom content x. With the increase of Mn atom content x, the crystal lattice constants and the unitcell volume V are increased. At the same time, the precipitation content of Mn and the impurity phase were exhibited obviously. The substitution of Si with Mn can increase the curie temperature of Gd5Si2Ge2 compound.