The effects of NiO microstructure, on the properties of sol-gel YBCO coated conductors

Bi-axially textured Ni tapes were oxidized to form NiO as alternative buffer layers for sol-gel YBCO coated conductors. We investigated growth and stability of YBCO films on nickel oxide buffer layers without using a cap layer. Microstructure of NiO, and effects of the microstructure on the properties of YBCO were also examined. To understand microstructure formation of NiO layers, parameters of surface oxidation process such as oxidation time, temperature and atmosphere were studied. Surface morphology, thickness of NiO and YBCO layers, were studied using environmental scanning electron microscopy (ESEM). We found that surface oxidation parameters strongly affect microstructure, thickness, and morphology of NiO, and the properties of YBCO. Resistance versus temperature measurements of YBCO coated conductors was done by 4-probe measurements.