Comparison between two kinds of Y-Ba-Cu-O films deposited from single sintered targets with Ba-poor 1:2:3 (=Y:Ba:Cu) compositions

Films of Y-Ba-Cu-O (YBCO) with zero resistance transition temperature exceeding 85 K were reproducibly prepared by DC magnetron sputtering using single sintered targets with nonstoichiometric (Ba-poor) compositions under the conditions of low oxygen partial pressure (0.6 Pa) and high argon-oxygen pressure (40 Pa). Their critical temperature, T/sub c/, correlates well with the Cu/Ba ratio in the films. The relation of T/sub c/ to the c-axis lattice parameter is very different from that for bulk ceramics and films deposited from a stoichiometric target at high oxygen partial pressure (4 Pa).<>