Experimental and theoretical studies of oxygen ordering in quenched and slow-cooled YBa2Cu3O7

Two curves for Tc vs in YBa2Cu3O7- are found in the literature; slow-cooled samples show 60 and 90 K plateaus while quenched specimens show a nearly linear decrease of Tc with increasing . We present a comprehensive electron-diffraction study of quenched specimens and show that there are pronounced differences in the oxygen ordering between quenched and slow-cooled samples. A simple model, in which the average antiphase domain size is the only adjustable parameter, is found to match all of the experimental electron-diffraction data to within measurement error. © 1992 The American Physical Society.