Basal plane oxygen vapor pressure of Co-doped YBa2Cu3O7−δ

Abstract
Transport data for YBa2Cu3−xCoxOz thin films, with x=0.3, 0.5, 0.75, and 1.0, are reported as a function of annealing history in O2 and O2/O3 at temperatures ranging from 200 to 500 °C. For x=0.3 and 0.5, O2/O3 anneals resulted in maximal Tc’s significantly higher than any previously reported, while in all cases the annealing substantially increased the film’s conductivity. Subsequent anneals in O2 resulted in oxygen loss, demonstrating that these materials have a much higher oxygen vapor pressure in the well-oxygenated state than YBa2Cu3O7−δ.