Microstructural features of epitaxial YBCO films: Tem study

Large areaTEM specimens from well epitaxially grown YBa2Cu3O7−x films were prepared parallel to the epitaxial surface for investigation of microstructures. Two sets of (001) microtwins are frequently seen with spacing of several decade nm. After a prolonged observation under TEM, the initial orthorhombic lattice can be transformed to a tetragonal one as a result of the effect by electron beam. Other types of lattice defects such as dislocations, low-angle subgrain boundaries and two types of epitaxy are also observed.