PREPARATION AND SUPERCONDUCTING PROPERTIES OF Y-BA-CU-O FILMS ON OXIDE POLYCRYSTALLINE SUBSTRATES BY CHEMICAL VAPOR-DEPOSITION

Y-Ba-Cu-O superconducting films were prepared on Y2O3-stabilized ZrO2 (YSZ), MgO and Al2O3 polycrystalline substrates by chemical vapour deposition using beta-diketone metal chelates as sources. The c-axis of YBa2Cu3Oy was mainly oriented perpendicular to the plane of the films obtained above 800-degrees-C. The films deposited on YSZ and MgO at 850-degrees-C showed zero resistivity at 90 K and 87 K, respectively. The superconducting transition temperature of 71 K was the highest among the transition temperatures of the films deposited on Al2O3. The critical current density (J(c)) of the film on YSZ was 8.0 x 10(3) A cm-2 and that of the film on MgO was 1.0 x 10(4) A cm-2 at 77.3 K and O T. J(c) measured at 77.3 K under an applied magnetic field of 15 T parallel to the film planes was 44 A cm-2 for the film on YSZ and 27 A cm-2 for the film on MgO. The temperature gradients of the upper critical field (-dB(c2)/dT) determined by the definition of zero resistivity for the film prepared on the YSZ substrate were 4.7 T K-1 and 1.0 T K-1 when the magnetic field was parallel and perpendicular to the film plane, respectively.