氟碳钙铈矿6R_2新多型的高分辨电镜研究  

A Study of New Polytype 6R_2 in Parisite by High Resolution Transmission electron Microscopy

作　　者：孟大维[1] 吴秀玲[1] 杨光明[1] 潘兆橹[1] 

机构地区：[1]中国地质大学测试中心,武汉430074

出　　处：《地球科学（中国地质大学学报）》1994年第5期655-661,T002,共8页Earth Science-Journal of China University of Geosciences

基　　金：国家自然科学基金(49102019)

摘　　要：用电子衍射和高分辨电子显微技术研究了钙稀土氟碳酸盐系列矿物中氟碳钙铈矿及其衍生体的微结构,发现了氟碳钙铈矿的6R_2新多型体,确定了其亚结构晶胞呈六方(H)对称,a＇=0.412nm,c＇＇＇=0.471nm,超结构晶胞呈菱面体(R)对称,a=0.714nm,c=8.478nm,可能的空间群为R(?)c和R3c.(?)取向的高分辨结构像显示出该多型体结构单元层沿c轴的有序堆垛及重复周期.[0001]取向的电子衍射和高分辨结构像表明,晶体沿垂直a、b轴方向存在位错、层错及畸变等非均匀结构现象.The microstructures of parisite and its derived polycrystal in the calcium-rare-earth fluorocarbonate minerals from Southwest China have been studied by means of high resolution transmission electron microscopy (HRTEM)(JEOL- 2000EX and Philips-CM12). The new polytype 6R2 of parisite has been discovered. The electron diffraction analysis shows that its substructure cell belongs to the hexagonal system with the parameters a' =0.412nm, c'' = 0.471nm, and the superstructure cell belongs to the trigonal system with the parameters a = 0.714nm,c=8.478nm, and possible space group is R3c and R3c . The lattice images and the high resolution electron micrographs of the new polytype 6R2 have been taken. The ordered stacking form along c axis as well as the repeat periods of structure unit layers in this new polytype have been revealed with the high resolution structure images from the direction [1210]. In addition, the electron diffraction and the high resolution structure images from the direction [0001] show that there are heterogeneous texture in the direction of perpendicular to a or b axis, such as dislocation, fault and distortion, etc.

关 键 词：氟碳钙铈矿 电子显微镜 6R2 

分 类 号：P575.2[天文地球—矿物学]