The diffusion of O in single crystals was determined by means of secondary ion mass spectrometry at 628 to 1073K. It was found that the slope of the Arrhenius plot changed at the temperature of transition from the orthorhombic to the tetragonal phase. The activation energies of O in the tetragonal and orthorhombic phases were 89.1 and 114.6kJ/mol, respectively, on the ab-plane and 284 and 126.9kJ/mol, respectively, in the c-axis direction. In the orthorhombic phase, the activation energies for the ab-plane and the c-axis direction were almost the same, but the diffusion coefficients in the ab-plane were larger than those in the c-axis direction by more than 3 orders of magnitude. At higher temperatures, in the tetragonal phase, the slope of the Arrhenius plot for the c-axis direction became larger and the diffusion coefficient for the c-axis became closer to that for the ab-plane.

Oxygen Tracer Diffusion in the Cu3Ba2YO7 Superconductor. S.Tsukui, M.Adachi, R.Oshima, H.Nakajima, F.Toujou, K.Tsukamoto, T.Tabata: Physica C, 2001, 351[4], 357-62