金属间化物（Sm_（1－x）Y_x）Fe_（17）N_y的占位及其相变研究

STUDY ON OCCUPATION AND STRUCTURE CHANGE OF INTEKMETALLIC COMPOUNDS(Sm_(1-x)Y_x)_2Fe_(17)N_y

主要通过ｘ射线衍射和穆斯堡尔谱等手段研究金属间化物（Ｓｍ＿（１－ｘ）Ｙ＿ｎ）＿２Ｆｅ＿（１７）Ｎ＿ｙ（ｘ＝０，０．２，０．４，０．６，０．８和１．０；２＜ｙ＜３）中镱原子的择优占位、氮原子的占位以及结构相变问题。由实验结果得出以下结论：（１）当ｘ＞０．５时．晶体结构发生相变，即由Ｔｈ＿ｚＺｎ＿（１７）型变至Ｔｈ＿ｚＮｉ＿（１７）型；（２）氮原子在以上氮化物中（除ｘ＝１．０外）不仅占据９ｅ（６ｈ）品位，还将占据１８ｇ（３ｂ）品位；（３）镱原子择优占据２ｂ晶位；（４）当ｘ在０．８～１．０的范围内存在自旋磁结构的相变，即由易ｃ轴各向异性变至易Ｃ平面各向异性。

X-ray diffraction and M ossbauer spectroscopy were used to study the preferen-tial occupation of Y for Sm atoms、the occupation of N atoms and structure change in《Smi,。YJ;Fe_17N/X一0,0.2.0.4,0.6,0.8 and 1.0;2<y<3).Thc cxperimental results confirmedthe following facts:(1) The crystal structure changed from the Th_2Zn_(17)-typc to the Th_2Ni_(17)-type when x exceeded 0.5;(2)The N atoms ofabove nitrides(except x=1.0) occupled noton1y 9e (6h)sites but also 18g(3b)sites ;(3)The Y atoms preferentially occupied the 2bsites;(4 )The spin magnetic structure changed from casy c axis anisotropy to easy c planeanisotropy as the yttrium content ranged from x= 0. 8 to 1.0.