TEM CHARACTERIZATION OF BUFFER LAYERS FOR EPITAXIAL YBA2CU3O7-DELTA GROWTH

Epitaxial buffer layers of Zr(Y)O-2, SrTiO3, and Y2O3/Zr(Y)O-2 deposit ed on single crystalline Al2O3, MgO, and Si substrates, respectively, are analysed by plane view TEM applying a special ''planar section'' p reparation technique. In all buffer layers a mosaic structure is revea led with the relative orientation of the mosaic blocks within some deg rees. In the case of the Y2O3/Zr(Y)O-2 buffer layer the mosaic structu re is ''replicated'' into the subsequently deposited superconducting f ilm. By this means a unique microstructure of the YBa2Cu3O7-delta film is created consisting of twin-free mosaic blocks.