Oxygen diffusion in observed by resistivity measurements

Abstract

In situ resistivity measurements have been used to monitor the oxygen uptake and removal for the ceramic system (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 is preserved up to 600 K, and that oxygen diffuses out of the oxides at temperatures higher than 600 K. However, the rate of oxygen removal from (PBCO) is greatly reduced as compared to the rate for pure (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 the in-diffusion rate depends slightly on the Pr concentration. The observed resistivity change for all of the YPBCO samples as they interchange oxygen with the gas phase indicates that the number of majority carriers in the oxides is mainly controlled by the oxygen content and seems to be independent of the Pr concentration, at least for .