Je. Diosa et al., OXYGEN DIFFUSION IN Y1-XPRXBA2CU3O7-DELTA OBSERVED BY RESISTIVITY MEASUREMENTS, Journal of physics. Condensed matter, 9(22), 1997, pp. 4621-4626
In situ resistivity measurements have been used to monitor the oxygen
uptake and removal for the ceramic system Y1-xPrxBa2Cu3O7-delta (YPBCO
) in the temperature range 300-1000 K. The study of the out-diffusion
of oxygen was performed by annealing the oxygenated samples in ambient
air at constant heating rates. We found that, independently of x, the
oxygen concentration O7-delta is preserved up to 600 K, and that oxyg
en diffuses out of the oxides at temperatures higher than 600 K. Howev
er, the rate of oxygen removal from PrBa2Cu3O7-delta (PBCO) is greatly
reduced as compared to the rate for pure YBa2Cu3O7-delta (YBCO), and
decreases with increasing x in YPBCO. The study of the in-diffusion of
oxygen was performed by annealing the deoxygenated samples in ambient
air at constant heating rates. We found that, independently of x, the
oxygen uptake takes place in the temperature range 550-750 K, where t
he in-diffusion rate depends slightly on the Pr concentration. The obs
erved resistivity change Delta rho(delta) for all of the YPBCO samples
as they interchange oxygen with the gas phase indicates that the numb
er of majority carriers in the oxides is mainly controlled by the oxyg
en content delta and seems to be independent of the Pr concentration,
at least for x less than or equal to 0.5.