Electron diffraction (LACBED) and HRTEM Moiré fringe pattern study of stress in YBaCuO thin film on Mg0

Abstract
Epitaxial stresses are studied by means of Large Angle Convergent Beam Electron Diffraction technique and Moiré fringe pattern obtained by High Resolution Transmission Electron Microscopy in pulsed laser deposited thin films of YBaCuO on MgO substrate. Grains with their c-axis parallel to the interface (c//) grow from the substrate up to the outer surface of the film. The c// grains, embedded in the c ⊥ host matrix, are studied from investigations of cross-sectional sample, by both LACBED performed on the MgO substrate just beneath the different orientations of the thin film, and by the Moiré fringe pattern obtained by tilting the interface of the sample. The broadening of the Bragg lines present in the LACBED disk together with the direction of the Moiré fringes, clearly indicate that the c// oriented grains embedded in a c ⊥ oriented YBaCuO matrix are under stress.