YBA2CU3OX FILMS PREPARED IN A PARTIAL-PRESSURE OF AIR USING PULSED-LASER DEPOSITION

YBa2Cu3Ox superconducting films have been deposited by laser depositio n on yttrium stabilized cubic zirconia (YSZ) substrates using a partia l pressure of air instead of oxygen. The T-c of these films was over 2 degrees higher than films made in the same deposition system using ox ygen. The films made using air had an on-set temperature higher than 9 3 K and an off-set temperature around 90 K, with typical transition te mperature widths less than 1 degree; while the films made using oxygen had typical-on-set temperatures around 90 K and off-set temperatures around 87 K. X-ray diffraction indicated that the films were oriented with the c-axis normal to the substrate surface. The critical current densities of the films, as obtained by dc transport measurements, were found to be on the order of 10(6) A/cm(2) at 77 K and self magnetic f ield, and the room temperature resistivities were about 245 mu Omega-c m. An unique aspect of these films was that the normal state resistivi ty ties showed nonlinear behavior with respect to temperatures. Howeve r, no secondary phase was detected by x-ray diffraction and SQUID magn etometry.