Microstructural observations of RBa2Cu3O7(R=Gd, Y, and Tm) superconductor thin crystals between 15 and 1000 K

摘要

Small crushed crystals of the new superconductor materials of the type RBa2Cu3O7(R=Gd, Y, and Tm) were studied by conventional transmission electron microscopy between 15 and 1000 K. Between 15 and 300 K a He‐liquid cold stage was used, while temperatures between 300 and 1000 K were obtained by focusing the electron beam. The thin‐edge areas unambiguously show the formation of the classical orthorhombic structure. The orthorhombic‐tetragonal transition, in the course of the cooling, was not observed. Electron diffraction results show the presence of various unknown structures and the BaCuO2compound. The crystals present few defects: Only some twins and dislocations have been observed.