On the Structure of Layered ß-CuIn5Se8. Electron Diffraction and High Resolution Electron Microscopy Study

The layered phase β-CuIn5Se8 is studied by means of electron diffraction and high resolution electron microscopy. It is found that this phase is characterized by a 5H layer sequence of the Se atoms. The distribution of cations causes a doubling of the lattice parameter along the c-axis and a tripling along the a-axis. Three other phases are found to exist in this compound and phase transitions between them are investigated. The 5H → 3C transition is shown to be a shear trans-formation, produced by the movement of partial dislocations along glide planes, located between two successive anion layers.