Abstract
High-resolution electron microscope images of α-AlB12 were quantitatively observed by using a high-voltage transmission electron microscope and the new Imaging Plate having a pixel size of 25 μm. In order to quantitatively evaluate the difference between the observed intensity and the calculated one, a residual index RHREM which indicates the accuracy of a calculated image was evaluated for 1440 sampling points in the unit cell projected along the [111] direction. The residual index RHREM of 0.0576 was obtained with the averaged high-resolution electron microscope image and the calculated image based on the structure model obtained from the X-ray diffraction study. In the observed high-resolution electron microscope image, some regions had extraordinarily higher intensity than other regions which were crystallographically equivalent to the regions. In a quantitative analysis of the observed images including those regions, the minimum RHREM at 0.0738 was obtained by varying the occupancy of Al atoms although the RHREM remarkably increased from the minimum value obtained in the quantitative analysis of the averaged image. The effects of a contamination layer covering the sample on the above quantitative analysis of high-resolution electron microscope images are briefly discussed.
