TRANSMISSION ELECTRON-MICROSCOPIC STUDIES OF YBBA2CU3O7-DELTA PRECURSOR FILMS FORMED ON SRTIO3 BY DIPPING-PYROLYSIS PROCESS

We prepared precursor films of YbBa2Cu3O7-delta by coating SrTiO3(001) single crystal substrate with metalorganic compounds solution and by heating at 425 degrees C. Then, microstructures of the precursor films were observed by transmission electron microscopy. The film heated ra pidly up to 425 degrees C was amorphous. On the other hand, the film h eated gradually was polycrystalline. After final annealing at 725 degr ees C, the former sample showed a sharp transition of the electric res istance around critical temperature (T-C). The latter one showed a bro ad transition. Therefore, we conclude that a high heating rate at the pre-treatment is important for achieving a sharp resistive transition of the final film.