Electron microscopy of satellite structure and twinning in HoBa2Cu3O7−x

Two different distributions of satellite reflections in electron diffractograms have been observed in HoBa 2 Cu 3 O 7−x after intense electron irradiation: diffuse elongated spots from orthorhombic materials, and sharp superlattice spots from material possibly transformed to tetragonal in the electron beam.- Two types of twin texture composed of sets of twin lamellae are observed, each involving four crystal orientations. The first type is assumed to originate in two genetic stages. In the second type, two adjacent crystal orientations occur which differ by about 1° in the more common configuration and by 2° in another configuration. In the junctions of the twin lamellae, the lattice planes are coherently connected and strongly bent.