The equilibrium O content in Cu3-xBa2CoxYO6, where x was between 0 and 0.8, was measured as a function of temperature and O pressure by means of coulometric titration at temperatures ranging from 600 to 850C, under O pressures of between 10-5 and 1atm. Changes in the partial molar enthalpy and entropy of the intercalated O were determined for various O and Co contents. The chemical diffusion of O was studied by means of thermogravimetric relaxation in an O-controlled atmosphere. The thermodynamic data were used to determine how the chemical diffusion coefficient, the thermodynamic factor and the random diffusion coefficient depended upon the O content in specimens with various Co concentrations. The O intercalation thermodynamics and diffusivity results provided evidence for the occurrence of ordering phenomena at the microscopic scale in the basal plane of the tetragonal solid solution. A model for the O diffusion was suggested which explained the large difference between the random and tracer diffusion coefficients.

Intercalation Thermodynamics and Chemical Diffusion of Oxygen in the Solid Solution YBa2(Cu,Co)3O6. E.B.Mitberg, M.V.Patrakeev, A.A.Lakhtin, I.A.Leonidov, V.L.Kozhevnikov, K.R.Pöppelmeier: Solid State Ionics, 1999, 120[1-4], 239-49