High-Resolution Electron Microscopy of Radiation Damage of YBa2Cu4Oy Superconductor Induced by 200 kV Electron Beam

Electron-induced structural decompositions of a YBa₂Cu₄O_y (124) type of high-T_c superconductor are examined with a 200-kV high-resolution transmission electron microscope (HRTEM). Partial conversions of the (CuO)₂ double chains into the (CuO) single ones are induced to form a disordered structure, and precipitation of the decomposition product, CuO, is observed at the edge of the electron-irradiated crystals. Such results of 200 kV electron beam irradiations are rather similar to the thermal decomposition process, while those due to higher-energy 1-MV electrons are the knock-on atom displacements that cause amorphization [Matsui et al., Jpn. J. Appl. Phys. 30 (1991) L1375].