Atomic disordering in YB56 detected by high-resolution electron microscopy with residual indices

Abstract

Abstract Disordering of both yttrium and boron atoms in YB56 was observed, in three dimensions, from difference images of high-resolution electron microscopy (HREM) and simulated images from an X-ray determined structural model. Averaged HREM images recorded using a slow-scan charge-coupled device camera from thin regions (less than 5 nm) along the [100], [110] and [111] directions of the YB56 were compared with calculated images based on the X-ray data. A residual index R HREM was used for image analysis to determine the crystal thickness and defocus value of the observed images. Based on the experimental conditions which minimized the R HREM values, difference images between observed and simulated images were calculated. These difference images observed along the three directions of the YB56 showed the atomic disorder, which are yttrium positions and boron clusters around the yttrium atoms. This approach is useful for the evaluation of disordered atomic positions in the crystal.