BASAL-PLANE OXYGEN VAPOR-PRESSURE OF CO-DOPED YBA2CU3O7-DELTA

Transport data for YBa2Cu3-xCoxO- thin films, with x= 0.3, 0.5, 0.75, and 1.0, are reported as a function of annealing. history in O-2 and O -2/O-3 at temperatures ranging from 200 to 500 degrees C. For x=0.3 an d 0.5,O-2/O-3 anneals resulted in maximal T-c's significantly higher t han any previously reported. while in all cases the annealing substant ially increased the film's conductivity. Subsequent anneals in O-2 res ulted in oxygen loss, demonstrating that these materials have a much h igher oxygen vapor pressure in the well-oxygenated state than YBa2Cu3O 7-delta. (C) 1998 American Institute of Physics.