Preparation of textured YBCO films using all-iodide precursors

We developed an all-iodide precursor approach to grow epitaxial YBa2Cu3O7-y (YBCO) films on single crystal substrates. The respective metal iodides we re used as the starting materials. Initially, yttrium and barium iodides we re dissolved in 2-methoxyethanol, whereas copper iodide was dissolved in am monium iodide/dimethylformamide solution. The solutions were mixed together and concentrated to give a 2.5-M total cation precursor solution. The prec ursor solutions were spin coated on SrTiO3 (100) substrates and heat-treate d at 800-830 degrees C in 300 ppm oxygen atmospheres. X-ray diffraction (XR D) results from the theta-2theta (theta-2 theta) scan, omega (omega) and ph i (phi) scans for the films revealed a (100) cubic texture. The full-width- at-half-maximum (FWHM) values for YBCO (105) and YBCO (005) were 1.3 degree s (in-plane epitaxy, Delta phi) and 0.42 degrees (out-of-plane epitaxy, Del ta omega), respectively. The YBCO films had a T-c of 90.3 K. The measured t ransport J(c), critical current density was 1.3 x 10(5) A/cm(2) at 77 K and self-field. (C) 1999 Published by Elsevier Science B.V. All rights reserve d.