2970 IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, VOL. 15, NO. 2, JUNE 2005 Growth and Properties of YBCO-Coated Conductors Fabricated by Inclined-Substrate Deposition Beihai Ma, Krishna K. Uprety, Rachel E. Koritala, Brandon L. Fisher, Steve E. Dorris, Dean J. Miller, Victor A. Maroni, and U. (Balu) Balachandran Abstract—YBCO-coated conductors with high current-carrying capability are desirable for electric power transmission applica- tions. Inclined-substrate deposition (ISD) is capable of producing high-quality biaxially textured template films, which are impor- tant for fabrication of YBCO-coated conductors. We have grown biaxially textured ISD-MgO template films on flexible metallic sub- strates at deposition rates of 2–10 nm/sec. Columnar grains with a roof-tile-shaped surface structure were observed on the ISD-MgO films. X-ray pole figure analysis revealed that the ISD-MgO film is biaxially textured and its c-axis is titled at an angle from the sub- strate normal. Strontium ruthenium oxide (SRO) buffer films were epitaxially grown on ISD-MgO by pulsed laser deposition prior to the deposition of YBCO. Low -scan full-width at half maximum (FWHM) values of 6 and 7 were observed for YBCO and SRO, respectively. of 91 K with a sharp transition and transport over 1.4 at 77 K in self-field were measured on YBCO coated conductors grown with ISD MgO architectures using a SRO buffer. Index Terms—Coated conductor, inclined-substrate deposition, pulsed laser deposition, SRO buffer, YBCO thin film. I. INTRODUCTION T HE second generation (YBCO)-coated conductors are promising for high current-carrying wires and many other electric power devices operating at tempera- tures that approach liquid nitrogen [1]–[3]. A textured template is needed for fabrication of biaxially aligned YBCO films to overcome weak links and, therefore, to achieve high critical current density in the YBCO films on flexible metallic substrates [4]. Several techniques, including ion-beam-assisted deposition (IBAD), rolling-assisted biaxially textured substrates (RABiTS), and inclined-substrate deposition (ISD), have been developed in recent years [5]–[8]. When compared with IBAD and RABiTS, the ISD process produces textured films at high deposition rates without the need of an assistant ion source and is independent of the deformation/recrystallization properties of the metallic substrates [9]. Manuscript received October 4, 2004. This work was supported by the U.S. Department of Energy, Office of Electric Transmission and Distribution, as part of a DOE program to develop electric power technology, under Contract W-31-109-Eng-38. B. Ma, K. K. Uprety, R. E. Koritala, B. L. Fisher, S. E. Dorris, and U. Balachandran are with the Energy Technology Division, Argonne National Laboratory, Argonne, IL 60439, USA (e-mail: bma@anl.gov). D. J. Miller is with the Materials Science Division, Argonne National Labo- ratory, Argonne, IL 60439, USA. V. A. Maroni is with the Chemical Engineering Division, Argonne National Laboratory, Argonne, IL 60439, USA. Digital Object Identifier 10.1109/TASC.2005.848684 Biaxially textured magnesium oxide (MgO) thin films grown by ISD on metallic substrates (ISD-MgO) are promising for the fabrication of YBCO-coated conductors. ISD-MgO films exhibit terraced surface morphology and tilted c-axis orienta- tion. This increases the difficulty for fabrication of high-quality YBCO on ISD-MgO substrates. High current-carrying YBCO films were deposited on ISD-MgO substrates by pulsed laser de- position (PLD) using yttria-stabilized zirconia (YSZ) and ceria double buffer layers [10]. The utilization of the double buffer on ISD-MgO resulted in a unique orientation relationship between the YBCO and ISD-MgO. Biaxially textured YBCO has its c-axis parallel to the substrate normal, whereas the c-axis of ISD-MgO template is tilted away. An FWHM of was observed for YBCO (113) -scan peaks. Further improvement in biaxial alignment for YBCO grown on ISD-MgO using YSZ and double buffer is extremely challenging because of the nonepitaxial growth and relatively rough terminal surface of ISD-MgO. Nevertheless, a transport at 77 K in self-field was reported for YBCO deposited on ISD-MgO using the YSZ and double buffer [10]. To simplify the layered structure of YBCO coated conductors grown with the ISD-MgO architecture, we investigated stron- tium ruthenium oxide ( , SRO) as an alternative buffer material. The SRO buffer layer and YBCO films were sequen- tially deposited by PLD on the ISD-MgO grown on metallic substrates by e-beam evaporation. Surface morphology was in- vestigated by scanning electron microscopy (SEM) and surface roughness was measured by atomic force microscopy (AFM). Raman spectroscopy was employed to evaluate the quality of the YBCO. X-ray pole figures, as well as - and -scans, were used for texture analysis. In this paper, we also report the orientation relationships and superconducting properties of YBCO-coated conductors fabricated using the simplified ISD-MgO architecture. II. EXPERIMENTAL PROCEDURE MgO films were deposited on electropolished Hastelloy C276 (HC) substrates by ISD using e-beam evaporation at room temperature with a deposition rate of 2–10 nm/sec. HC was chosen as substrate material because of its desir- able mechanical strength and compatible thermal properties. Root-mean-square (RMS) surface roughness of 0.25 nm was measured on the electropolished HC substrates by AFM. Details of experimental setup and deposition conditions for ISD-MgO were reported earlier [7]. SRO buffer films were de- posited at an elevated temperature (700–800 ) in 50 mTorr 1051-8223/$20.00 © 2005 IEEE