Intermediate Phase Evolution of YBCO Superconducting Films Fabricated by Fluorine Free MOD Method

Abstract

The second generation high temperature superconducting tapes, which use ReBCO film as superconducting layer, are considered to have enormous potential in practical applications because of its high operation temperature (up to 77 K), high superconducting performance under strong field and good mechanical properties relative to other practical superconducting wires / tapes. Among its preparation processes, fluorine free-metal organic deposition (FF-MOD) technique has been a research hotspot in recent years because of its unnecessity of vacuum environment, fast pyrolysis and crystallization growth rate, and environmental friendliness. In this paper, YBCO films were prepared on the CeO2 / IBAD-MgO / Y2O3 / Al2O3 / Hastelloy C276 technical substrate by FF-MOD technique. To systematically study the process of its phase evolution, the samples were quenched in different temperatures and followed by the characterization of XRD, ATR-IR and SEM. It is shown that the reaction between BaCO3 and the oxides of Y and Cu elements does not produce YBCO directly, but experienced a more complicated intermediate process. Besides, the formed YBCO crystals are randomly oriented at first, and then converted into a biaxially textured structure.