OXYGEN DESORPTION FROM HIGH-TC YBA2CU3O7-0.05, YBA2CU3O7-0.5

From a temperature-programmed desorption study employing a quadrupole mass spectrometer, the superconducting oxide YBa//2Cu//3O//7// minus // delta ( delta equals 0. 05) showed two distinc oxygen desorption peaks, one below and one above 470 degree C. The activation energy of oxygen desorption of the superconducting oxide was 28 Kcals/mole while that of the nonsuperconducting oxide (YBa//2Cu//3O//6//. //5) was 54 Kcals/mole. No impurity peaks due to H//2O, CO and CO//2 from the bulk or adsorbed on surfaces could be observed when a well-prepared superconducting oxide was heated up to 650 degree C.