A STUDY OF THE MASS-TRANSPORT PROPERTIES OF THE SOLID-STATE COPPER(I) ION CONDUCTOR RB4CU16I7CL13 AND ITS APPLICATION IN THE DETERMINATION OF THE THERMODYNAMIC STABILITY OF ND2CUO4

The preparation of CuZr2P3O12 from NH4H2PO4, Cu2O and ZrO2 is described. The electrochemical behaviour of the solid state cell Pt/CuZr2P3O12/Pt was studied by impedance spectroscopy. For the first time copper was titrated through the solid state cell Cu/CuZr2P3O12/Au at 1073 K, demonstrating that CuZr2P3O12 is a copper(I) ion conductor. CuZr2P3O12 has a copper ion conductivity of 3.4 S m-1 at 1073 K, and an activation energy of 0.42 eV for the temperature range 673-1273 K. CuZr2P3O12 is unstable with respect to oxidation, therefore electrochemical measurements are restricted to nonoxidizing environments which limits its practical use. An attempt was made, given these constraints, to determine the free energy of formation of Nd2CuO4