Epitaxial stress study by large angle convergent beam electron diffractionand high-resolution transmission electron microscopy Moire fringe pattern

Epitaxial stresses are studied by means of large angle convergent beam elec tron diffraction (LACBED) and Moire fringe patterns obtained by high-resolu tion transmission electron microscopy in pulsed laser deposited thin films of Y-Ba-Cu-O on MgO substrate. Grains with their c-axis parallel to the int erface grow from the substrate up to the outer surface of the film. These g rains, embedded in the c-axis normal to the interface host matrix, are stud ied in cross-sectional samples, by both LACBED performed on the MgO substra te just beneath the different orientations of the thin him, and by the Moir e fringe patterns obtained by tilting the interface of the sample. The broa dening of the Bragg lines present in the LACBED disk together with the dire ction of the Moire fringes, clearly indicate that the c(//)-oriented grains embedded in a c(perpendicular to)-oriented Y-Ba-Cu-O matrix are under stre ss. (C) 2000 Elsevier Science S.A. All rights reserved.