摘要
Ｓｒ＿（１０）Ｎｄ＿４Ｃｕ＿（２４）Ｏ＿（４１）选区电子衍射和会聚束电子衍射研究表明，它的整体结构由两个沿ｃ方向相互穿插的基本结构Ⅰ和Ⅱ构成。两个基本结构Ⅰ和Ⅱ的空间群和晶胞参数分别为Ｇ＿１＝Ｆｍｍｍ，ａ＿１＝１１．３８，ｂ＿１＝１２．９０，ｃ＿１＝３．９１和Ｇ＿２＝Ａｍｍｍ，ａ＿２＝１／２ａ＿１＝５．６９，ｂ＿２＝１２．９６，ｃ＿２＝２．７４。利用超空间群理论，描述调制的整体结构和调制的亚结构对称性的空间群由会聚束电子衍射测定的基本结构的对称性推导获得。它们为，（γ＿０＝ｃ＿１／ｃ＿２），调制波矢。
The structure of compound Sr_(10)Nd_4Cu_(24)O_(41) has been studied by selected-area and convergent-beam electrondiffraction. It is shown that the whole structure is constructed from two interpenetrating basic structures,re-ferred as Ⅰ and Ⅱ, with different periods along the c direction. The three-dimensional space groups and cell di-mensions of the basic structures are determined as:G_1=Fmmm,a_1=11. 38,b_1=12. 90 and c_1=3. 91 for Ⅰ andG_2=Ammm,a_2=5. 69,b_2=12. 90 and c_2=2. 74 for Ⅱ. By applying the superspace formalism the superspacegroup characterizing the symmetry of the whole composite modulated structure and the subsystem superspacegroups characterizing modulated substructures are derived from the CBED-determined symmetries of two indi-vidual basic structures. They are foud to be (γ_0=c_1/c_2),with the modulation wave vec-tor q=q_1=c_2and
出处
《电子显微学报》
CSCD
1994年第2期125-128,共4页
Journal of Chinese Electron Microscopy Society
