MOCVD SUPERCONDUCTING OXIDE-FILMS

Preparation of high-T(c) superconducting oxide films by MOCVD, their film structure and superconducting properties are reviewed from the standpoint of "nano-composites" and "fine-composites". Y-Ba-Cu-O (YBCO) films formed on SrTiO3(100) at 850-degrees-C showed a superconducting transition temperature with zero resistivity above 90 K. The maximum critical current density was 2.0 x 10(6) A/cm2 at 77.3 K and 0 T, and 6.5 x 10(4) A/cm2 at 77.3 K and 27 T. CuO and a-axis oriented YBCO grains were contained in the matrix of c-axis oriented YBCO. A transmission electron microscope observation revealed that inclusions of about 10-30 nm were embedded in the a-b plane of YBCO. MOCVD-YBCO films prepared on MgO(100) were used for superconducting devices. Some studies on the MOCVD films of Bi-Sr-Ca-Cu-O and Tl-Ba-Ca-Cu-O are also reviewed.