Oxygen desorption from YBa sub 2 Cu sub 3 O sub 7 minus sub x and Bi sub 2 CaSr sub 2 Cu sub 2 O sub 8+. delta. superconductors

Oxygen desorption experiments from YBa{sub 2}Cu{sub 3}O{sub 7{minus}{ital x}} (YBCO) and Bi{sub 2}CaSr{sub 2}Cu{sub 2}O{sub 8+{delta}} (BSCCO) superconductors were carried out using a quadrupole mass spectrometer for monitoring the desorbing species and x-ray photoemission spectroscopy for surface characterization. Molecular oxygen was found to desorb from both superconductors following photoirradiation with ultraviolet/optical radiation and subsequent heating at over 150 {degree}C. Both YBCO and BSCCO were found to have similar oxygen desorption rates and similar activation energies (10{sup 12}--10{sup 13} molecules/cm{sup 2} s and {similar to}1.5 eV/molecule, respectively). The desorption data as well as the x-ray photoemission data indicate that the oxygen desorption is not intrinsic to the superconductors but rather due to molecular oxygen entrapped in the material.