Morniroli J-P, Redjaimia A
Laboratoire de Métallurgie Physique et Génie des Matériaux, USTL, ENSCL, CNRS, BâtC(6), Cité Scientifique, 59655 Villeneuve d'Ascq, France.
J Microsc. 2007 Aug;227(Pt 2):157-71. doi: 10.1111/j.1365-2818.2007.01800.x.
The possible space groups of a crystal can be identified from a few zone axis microdiffraction patterns provided the position (and not the intensity) of the reflections on the patterns is taken into account. The method is based on the observation of the shifts and the periodicity differences between the reflections located in the first-order Laue zone (FOLZ) with respect to the ones located in the zero-order Laue zone (ZOLZ). Electron precession microdiffraction patterns display more reflections in the ZOLZ and in the FOLZ than in the conventional microdiffraction patterns and this number increases with the precession angle. It is shown, from the TiAl example given in the present study, that this interesting feature brings a strong beneficial effect for the identification of the possible space groups since it becomes very easy to identify unambiguously the FOLZ/ZOLZ shifts and periodicity differences. In addition, the diffracted intensity on the precession patterns is the integrated intensity and this intensity can also be used to identify the Laue class.
只要考虑到图案上反射的位置（而非强度），就可以从一些晶带轴微衍射图案中识别出晶体可能的空间群。该方法基于观察位于一阶劳厄区（FOLZ）的反射相对于位于零阶劳厄区（ZOLZ）的反射的位移和周期差异。与传统微衍射图案相比，电子进动微衍射图案在ZOLZ和FOLZ中显示出更多的反射，并且这个数量会随着进动角的增加而增加。从本研究给出的TiAl示例可以看出，这一有趣的特征对可能的空间群的识别带来了强大的有益效果，因为很容易明确识别出FOLZ/ZOLZ的位移和周期差异。此外，进动图案上的衍射强度是积分强度，该强度也可用于识别劳厄类。
