Effect of Firing Temperature on Microstructure and Superconductivity of YBCO Films Derived from Low-Fluorine Solution

Abstract

Using a low-fluorine solution, YBa2Cu3O7-x (YBCO) superconducting films were prepared on LaAlO3 (LAO) substrates by dip-coating method. YBCO films were fired at different temperatures with same oxygen pressure of 1.3 vol% and water vapor pressure of 7.4 vol%. Effect of firing temperature on film microstructure and superconductivity was investigated. The results indicated that YBCO films with high-degree c-axis orientation (the degree of c-axis orientation reached 96%) can be obtained when heat treated at 800 °C. At this temperature YBCO films were grown on LAO with cubic-on-cubic mode, resulting in a high critical transition temperature (Tc) of 91.5 K, and critical current density (Jc) of lager than 1 MA/cm2. However, when fired at lower temperatures, YBCO films trended to form a-axis grains, which degraded Jc of films. And a higher heat treatment temperature also depressed superconductivityof YBCO films.