An Electron Microscope Examination of Scandium Sesquisulphide, Sc2S3, and Its Mode of Disordering in the Electron Beam

Abstract

zone-axis structure images of the semiconductor compound Sc2S3 show the ordered arrangement of the unoccupied cation positions, which gives rise to a superlattice of the NaCl (B1, ScS) structure in three dimensions. The experimental images are adequately simulated by multislice computations. Electron-beam irradiation damages the crystal and the image changes in a complex way. Significant structural changes were directly observed in lattice images and diffraction patterns. Some of this resembles the disorder, believed to be grown in, which consists of antiphase boundaries resulting from the systematic displace- ment of slabs of structure. (For single crystal: a = 10.376 (2), b = 7.3775 (9), c = 22.033 (6) A.)