Microdomains and diffues scattering in K_2In_(12)Se_(19)

摘要

Electron and X-ray diffraction studies on the new compound K_2In_(12)Se_(19) indicate disorder of one-dimensional units due to the existence of pronounced diffuse scattering. The diffuse intensities are torus-shaped, with the axes of the rings collinear to c*. Observations by high-resolution electron microscopy (HREM) confirm the presence of three-dimensionally ordered domains with vqariable size which are separated by antiphase boundaries. The sizes of the domains determine the shape of the diffues intensity. Starting from the average structure it is possible to develop a model of domains which are three-dimensionally ordered.This model serves as a basis for simulated HREM images and electron diffraction patterns that show good agreement with experimental data. The diffuse scattering could be simulated qualitatively on the basis of a nonperiodic model of the real structure which consists of randomly packed rods.