Abstract
A chemical spray pyrolysis method has been applied to grow epitaxial films of a high T c Y-Ba-Cu-O compound (YBCO) on (001)MgO. Films as thin as 0.6 μm in thickness was found to exhibit excellent superconducting transition behavior. For films up to 2 μm in thickness, typical values of T c onset, T c zero and transition width (90%-10%) were measured to be 82, 76, and 1.5 K, respectively. Both plan-view and cross-sectional transmission electron microscopy revealed that the orientation relationships between the epitaxial films and the substrate are [001]YBCO//[001]MgO and (110)YBCO//(200)MgO. Twins, which may be perceived as domains that are rotated 90°along the c axis of the thin films with respect to the substrate, were found to be copiously present. The influences of the configuration of the oriented growth of overlayer thin films on the superconducting properties are addressed. The advantages of the chemical spray pyrolysis in producing superconducting thin films are outlined.