Processing and transport characteristics of YBCO tape conductors formed by IBAD method

Biaxially aligned YBa2Cu3O7-x (YBCO) films were fabricated on random Ni-based alloy tapes with textured YSZ buffer layers deposited by ion-beam-assisted deposition (IBAD). Ar+ ion bombardment was found to have significant effects on the crystalline structure of the YSZ buffer layers to align a [100] axis with the substrate normal and a [111] axis with the bombarding beam axis. The alignment mechanism is discussed with the structural properties of the YSZ films based on several proposed models. The azimuthal distribution of the a- and b-axes of the YBCO film on the top of the well-textured YSZ film was restricted to 10.2 degrees FWHM. The high J(c) value of 1.13 x 10(6) A cm (77 K, 0 T), the large I-c value of 103 A (77 K, 0 T), the clear longitudinal field effect (enhanced by 1.7 at 77 K, 0.5 T), and the low self-field AC losses in accordance with the Norris' formula for thin strip conductors were observed. All the transporting properties indicated that the biaxially aligned structure is a promising way to avoid percolated structures of superconducting current paths in YBCO conductors. (C) 1998 Elsevier Science Ltd. All rights reserved.