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

摘要

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 superconductivity of YBCO films.