会聚束电子衍射测定晶体点群的实验流程

本文设计了两套应用会聚柬电子衍射(CBED)测定晶体点群的优化实验流程图。一套为应用CBED测定晶体点群的一般流程图，它适合于对完全未知的晶体进行点群测定，如透射电镜下发现的未知微细包裹体或未知出溶相等；另一套为已知晶系情况下应用CBED测定晶体点群的实验流程图，它适用于已有X射线衍射或选区电子衍射数据的情况。这两套实验流程图非常详尽，流程图各分支的终点都是唯一的点群，具有操作性强的特点。使得测定晶体点群的实验变得更加简便快捷，尤其适合于对天然细分散矿物晶体点群的测定。并给出了两个应用实例，镁铝榴石及硅钛铈铁矿晶体点群的测定。

Experimental process for point-group determination by convergent-beam electron diffraction

In this paper, two sets of flow charts for point group determination by convergent beam electron diffraction (CBED) were given. The first is a general flow chart. It can be used to determine the point group of an unknown specimen, such as small enclosures or exsolution phases found by TEM, which never be studied by X ray diffraction (XRD) or selected area electron diffraction(SAED). The second is a special flow chart for point group determination by CBED when the crystal system of the specimen have been determined by XRD or SAED. These two flow charts give very detailed information for the point group determination, and are very useful in practice. They can make the experiment much easier. Finally, two examples were given to show how to use these flow charts in determination of crystal point group.