YBa/sub 2/Cu/sub 3/O/sub x/ films prepared in a partial pressure of air using pulsed laser deposition

YBa/sub 2/Cu/sub 3/O/sub x/ superconducting films have been deposited by laser deposition on yttrium stabilized cubic zirconia (YSZ) substrates using a partial pressure of air instead of oxygen. The T/sub c/ of these films was over 2 degrees higher than films made In the same deposition system using oxygen. The films made using air had an on-set temperature higher than 93 K and an off-set temperature around 90 K, with typical transition temperature 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/sup 6/ A/cm/sup 2/ at 77 K and self magnetic field, and the room temperature resistivities were about 245 /spl mu//spl Omega/-cm. A unique aspect of these films was that the normal state resistivities showed nonlinear behavior with respect to temperatures. However, no secondary phase was detected by X-ray diffraction and SQUID magnetometry.<>