Studies on chemical Vapor Deposition of High-temperature Superconductor for Wire Application

研究了化学气相沉积Y-Ba-Cu-O超导氧化物制备超导导线的方法。衬底采用y_2o_3稳定的多晶ZrO_2 （YSZ）、MgO、Al_2O_3和哈氏合金，可以制成长纤维和带。YBa_2Cu_3Oy的c轴主要垂直于衬底平面。在90k、87k和87k下，沉积在YSZ、MgO和YSZ涂层的哈氏合金金属表面的薄膜分别表现为零电阻率。在没有YSZ涂层的Al_2O_3和Hastelloy表面沉积的薄膜的超导转变温度低于77 K。在77.3 K和0 T条件下，在15t平行于衬底平面的外加磁场作用下，在77.3 K条件下，沉积在YSZ上的薄膜的临界电流密度（J_c）为8 × 10^3 A/cm^2，涂在YSZ上的薄膜的临界电流密度（J_c）为6.4 × 10^6 A/cm^2，涂在YSZ上的薄膜的临界电流密度为4.7 × 10^2 A/cm^2。在低氧分压条件下，采用CVD法在700℃的温度下成功制备了高j_c的Y-Ba-Cu-O超导薄膜。这种高j_c薄膜以前只能通过CVD在850℃下获得。

Chemical vapor deposition (CVD) of Y-Ba-Cu-O superconductiong oxide were investigated for production of superconducting wires. The substrates used were polycrystallne Y_2O_3-stabilized ZrO_2 (YSZ), MgO, Al_2O_3, and Hastelloy from which long fibers and tapes can be shaped. The c-axis of YBa_2Cu_3Oy was mainly oriented perpendicular to the subtrate plane. The films deposited on YSZ, MgO and YSZ-coated Hastelloy metal showed zero resistivity at 90 K, 87 K and 87 K, respectively. The superconducting transition temperature of the films deposited on Al_2O_3 and Hastelloy without the YSZ coating layer was below 77 K. The critical current density (J_c) of the films deposited on YSZ was 8.0X10^3 A/cm^2 and that of the film on YSZ-coated Hastelloy was 6.4X10^6 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 substrate plane was 6.4X10^3 A/cm^2 for the film on YSZ and 4.7X10^2 A/cm^2 for the film on YSZ-coated Hastelloy.High-J_c Y-Ba-Cu-O superconducting films were successfully prepared at 700ﾟC by CVD under low oxygen partial pressure during film depostition. Such high-J_c films could previously be obtained only at 850ﾟC by CVD.