一、引言 尽管X射线衍射是测定晶体结构最有效的方法。但当某些高度分散的物质,得不到足够大的单晶时,用X射线衍射方法测定其晶体结构就有一定困难。此时,可利用电子衍射的优越性弥补X射线的不足。一个非常小的薄晶体,只要线性大小为几千埃,在电子显微镜下,就能给出很好的电子衍射花样。一张单晶电子衍射花样只代表一个倒易点阵平面。为了收 I. INTRODUCTION Although X-ray diffraction is the most effective method of determining crystal structure. However, when some highly dispersed materials can not obtain a sufficiently large single crystal, it is difficult to determine the crystal structure by the X-ray diffraction method. In this case, the deficiency of X-ray can be compensated by the superiority of electron diffraction. A very small thin crystal, as long as the linear size is a few thousand angstroms, gives good electron diffraction patterns under the electron microscope. A single crystal electron diffraction pattern represents only one reciprocal lattice plane. In order to close