High-current Y-Ba-Cu-O superconducting films by metal organic chemical vapor deposition on flexible metal substrates

A metal organic chemical vapor deposition (MOCVD) method has been developed to achieve high currents in Y-Ba-Cu-O (YBCO) superconducting films deposit ed on biaxially textured buffer layers on polycrystalline (untextured) flex ible metal substrates. Optimization of the MOCVD process parameters has yie lded critical currents (I-c) greater than 50 A and critical current densiti es (J(c)) higher than 1 MA/cm(2) at 77 K in self-field conditions. High val ues of critical currents were found to be maintained also in the presence o f a magnetic field. At 75 K, with the magnetic field perpendicular to the c -axis (B perpendicular to c), J(c) values of 570,000 A/cm(2) (I-c = 20 A) a nd 240,000 A/cm(2) (I-c = 8.5 A) were achieved in fields of 1 and 5 T respe ctively. With the magnetic field parallel to the c-axis (B parallel to c), J(c) values of 215,000 A/cm(2) (I-c = 7.6 A) and 100,000 A/cm(2) (I-c = 3.6 A) were achieved in fields of 1 and 2.5 T respectively. At 64 K, the J(c) values were 1.2 MA/cm(2) (I-c = 43 A) and 770,000 A/cm(2) (I-c = 27 A) at 2 and 5 T respectively in the B perpendicular to c orientation. In the B par allel to c orientation, the J(c) values were 680,000 A/cm(2) (I-c = 23.7 A) , 520,000 A/cm(2) (I-c = 18.2 A) and 300,000 A/cm(2) (I-c = 10.6 A) at 1, 2 , and 5 T respectively. (C) 2000 Elsevier Science B.V. All rights reserved.