钙稀土氟碳酸盐中四种B_(10)S_8新规则混层矿物的透射电镜研究

TEM STUDY OF THE FOUR B_(10)S_8 NEW REGULARLY MIXED-LAYER MINERALS IN CALCIUM RARE-EARTH FLUOROCARBONATE

根据HRTEM研究，在四川西昌地区的钙稀土氟碳酸盐矿物衍生多晶体中发现了四种不同的B10S8型[即氟碳怖矿（B）／直氟碳钙铈矿（S）为10：8]新规则混层矿物（B10S8－I，B10S8－Ⅱ，B10S8-Ⅱ和B10S8－Ⅳ）。用SAED和HREM方法确定了四种新规则混层矿物的晶体结构对称性、晶胞参数、结构堆垛模式及晶体化学式等。四种B10S8新规则混层矿物结构中，Ce－F离子层的堆垛层序以及两个Ce－F离子层之间的碳酸根离子层的排列方式均不同。同时还观察到该类矿物中的畸结构及堆垛层错等。

From the high-resolution transmission electron microscopic (HRTEM ) study, four differ-ent new regularly mixed-layer minerals with l0: 8 type of bastnaesite/synchisite (B,,S,- I, B,,S,-E, B,,S,w M, and B,,S,- lV ) were discovered in the syntactic polycrystals of calcium rare-earth fluo-rocarbonate minerals from Xichang. Sichuan Province. Their crystal systems, cell parameters,structural stacking models and crystallochemical formulas were determined by means of selectedarea electron diffraction (SAED) and HRTEM methods. The Ce-F ion layers take different stack-ing successions and the (CO,) ion groups between two Ce-F ion layers take different arrangementsequences. The heter0gene0us textures such as lattice domains and stacking faults were also ob-served and discussed.