Growth and superconducting properties of YBa2Cu3O7 films on silver substrates by MOCVD in magnetic fields

YBa2Cu3O7 (YBCO) films were grown on polycrystalline silver substrates by m etalorganic chemical vapor deposition (MOCVD) in high magnetic fields. It i s demonstrated that a magnetic field affected the microstructure of the fil ms on polycrystalline silver substrates. Large square-shaped grains were ob served in the 0 T films, The grain size was drastically reduced by applicat ion of a few tesla fields, then changed to small grains with an irregular s hape above 4 T. Furthermore, it is found that application of a large magnet ic field during the deposition improved the crystallinity and grain connect ivity of YBCO films. leading to the improvement of the critical current den sity J(c). (C) 2001 Elsevier Science B.V. All rights reserved.