IOP PUBLISHING SUPERCONDUCTOR SCIENCE AND TECHNOLOGY Supercond. Sci. Technol. 23 (2010) 014005 (7pp) doi:10.1088/0953-2048/23/1/014005 Enhanced flux pinning in MOCVD-YBCO films through Zr additions: systematic feasibility studies T Aytug 1 , M Paranthaman 1 , E D Specht 1 , Y Zhang 1 , K Kim 1 , Y L Zuev 1 , C Cantoni 1 , A Goyal 1 , D K Christen 1 , V A Maroni 2 , Y Chen 3 and V Selvamanickam 3 1 Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA 2 Argonne National Laboratory, Argonne, IL 60439, USA 3 SuperPower, Incorporated, 450 Duane Avenue, Schenectady, NY 12304, USA E-mail: aytugt@ornl.gov Received 17 May 2009, in final form 7 July 2009 Published 9 December 2009 Online at stacks.iop.org/SUST/23/014005 Abstract Systematic effects of Zr additions on the structural and flux pinning properties of YBa 2 Cu 3 O 7−δ (YBCO) films deposited by metal–organic chemical vapor deposition (MOCVD) have been investigated. Detailed characterization, conducted by coordinated transport, x-ray diffraction, scanning and transmission electron microscopy analyses, and imaging Raman microscopy have revealed trends in the resulting property/performance correlations of these films with respect to varying mole percentages (mol%) of added Zr. For compositions 7.5 mol%, Zr additions lead to improved in-field critical current density, as well as extra correlated pinning along the c-axis direction of the YBCO films via the formation of columnar, self-assembled stacks of BaZrO 3 nanodots. (Some figures in this article are in colour only in the electronic version) 1. Introduction In order to realize the full potential of high temperature superconducting wires (HTS coated conductors) for various commercial electric-power equipment, the flux pinning properties of REBa 2 Cu 3 O 7−δ films (REBCO, RE = Y or a rare earth element) need to be improved in a controlled, reproducible and practical fashion [1–3]. In fact, these are the key requirements for scalable deposition approaches producing large-scale, long-length, continuous conductors. Improvements in pinning efficiency not only enhance the critical current density, J c , under high magnetic fields, B , but also may help reduce the field dependent anisotropy in J c for in-field orientations ranging from the ab-plane to the c-axis. The latter advancement is especially important for such power utility applications as motors, generators, and transmission lines, where HTS cables experience varying magnetic field strengths and directions. In recent years, the issue of improving the effective pinning of magnetic flux lines in HTS films has been successfully addressed by many groups through manipulation of defects in REBCO film matrix [3]. That is, through various methods of deposition-controlled nanostructural engineering, additional pinning centers of different sizes and morphologies, in addition to the existing naturally formed growth-induced defects, have been introduced into REBCO films. One particularly successful and heavily studied dopant is BaZrO 3 (BZO), first incorporated into the YBCO films, in the form of 5– 100 nm size particles [4], by pulsed laser deposition (PLD). This was followed by the demonstration of strain-induced formation of columnar defects, comprising self-assembled nanodots and/or nanorods of BZO within the superconducting matrix [5–7]. Similar columnar defects were also observed by incorporation of yttria-stabilized zirconia (YSZ) in REBCO films [8]. The columnar defects have proven to be very effective for enhancing the pinning performance, especially for fields applied near the c-axis of the REBCO film. Creation of such columnar defects has recently been shown possible using the scalable and economically tenable technique of metal– organic chemical vapor deposition (MOCVD) [9]. 0953-2048/10/014005+07$30.00 © 2010 IOP Publishing Ltd Printed in the UK 1