Structural aspect of high-Jc MOD-YBCO films prepared on large area CeO2-buffered YSZ substrates

Abstract

YBa2Cu3O7 (YBCO) film was prepared by fluorine-free metalorganic deposition (MOD) on a 2-inch-diameter CeO2-buffered yttria-stabilized zirconia (CbYSZ) substrate. The MOD-YBCO films on a flat CbYSZ prepared using a metal acetylacetonate-based coating solution demonstrated high critical current density (Jc), the average being higher than 4 MA/cm2 at 77.3 K and in a self field using an inductive method. The Jc distribution was uniform in the whole area of the MOD-YBCO films on the large size substrates. Cross sectional transmission electron microscopic images of the MOD-YBCO film exhibited a very smooth CeO2/ YSZ and CeO2 buffer layer/ YBCO film interfaces. Both the buffer and the YBCO layers were dense; however, a small amount of (100)-oriented YBCO occurred inside the matrix of (001)-oriented YBCO layers. Also, some distinct dislocations were observed at the CeO2/ YBCO interface. From around the stepped surface of the CeO2 buffer layer there seemed to grow a slightly distorted (001)-oriented YBCO domain, however, the domain restored its (001)-oriented periodicity in the region at some distance above the steps. Such growth mode is considered to correlate the high Jc of the MOD-YBCO film with very small average roughness of CeO2 buffer layer.