The equilibrium O content of Cu6(Nd2/3Ce1/3),(Ba2/3Nd1/3)4O16+x was measured, by means of coulometric titration, at temperatures ranging from 550 to 820C and O partial pressures of between 0.001 and 1atm. On the basis of the results, the partial molar enthalpy and entropy of O were calculated as functions of the O content. The data were explained in terms of a point defect model, and the equilibrium constants of the redox and charge disproportionation reactions were derived. A phase transition was observed near to x = 1.83; a composition which nominally corresponded to 1 trivalent Cu cation per elementary unit.

M.V.Patrakeev, I.A.Leonidov, A.A.Lakhtin, V.L.Kozhevnikov, A.V.Nikolaev: Journal of Solid State Chemistry, 1995, 120[1], 146-50