Determination of crystal structure of omphacite

作     者：Qifang Zhang Zhesheng Ma Nicheng Shi 

作者机构：Minist Met Ind Ctr Remote Sensing Beijing 100029 Peoples R China China Univ Geosci Beijing 100083 Peoples R China 

出 版 物：《Chinese Science Bulletin》 (科学通报(英文版))

年 卷 期：1999年第44卷第10期

页      面：944-949页

核心收录：

学科分类：07[理学] 070205[理学-凝聚态物理] 08[工学] 080501[工学-材料物理与化学] 0805[工学-材料科学与工程（可授工学、理学学位）] 0703[理学-化学] 0702[理学-物理学] 

主　　题：omphacite crystal structure Pn space group. 

摘      要：The chemical formula of omphacite was expressed with （MⅡMⅠ）（Si, AI）2O6.Cations that occupied the MⅡ site were large cations such as Ca or Na, and Na/（Na+Ca） ratio ranged from 0.2 to 0.8; the 6-coordinated MⅠ site accommodated cations such as Mg, Fe2+,Al, Fe3+ ,and Al/（Al+Fe3+） ratio was more than 0.5 Omphacite space groups reported were C2/c, P2, P2/n, P2/c, cell parameters are a0 = 0.9600—0.9630 nm, b0 = 0.8750—0.8830 nm, C0 =0.5230—0.5290 nm,β = 106°40’—107°10’. The sample was picked up from the eclogites in Zhucheng County, Shangdong Province. The intensity data were collected with the RIGAKU RASA Ⅱ -S four-circle single crystal diffractometer. The correct structure model was obtained by using the Patterson method and Fourier synthesis, SHELX-76 program, structure refinement with 905 independent diffraction points （|F0| 3σ|F0 |）. After the structure parameter refinement, the R-factor reduced to 0.0515. The crystal structure analysis indicates that omphacite has a new