A study was made of O mobility by using a very low frequency mechanical spectroscopic technique which permitted measurements to be made in a temperature range in which the O concentration remained stable. In the case of O-rich specimens with the orthorhombic I phase, a single relaxation peak was observed. It was found that the activation energy varied from 0.8 to 1.3eV, and was a complex function of the O concentration. At lower O contents, a second relaxation peak was observed which coexisted with the first one. Its energy was equal to about 1.10eV; regardless of the concentration. A model which involved O atom jumps on CuO planes was proposed in order to explain the results.

P.Gadaud, B.Kaya: Journal of Alloys and Compounds, 1994, 211-212, 296-9