Synthesis, Sintering, Transport Properties, and Surface Exchange of La2Ni0.9Cu0.1O4+δ

Dense La2Ni0.9Cu0.1O4+delta ceramics were sintered from powders synthesized through a wet-chemical citrate nitrate route with optimized ratios of citrate to nitrate. Less citrate decreases the required sintering temperature and improves the oxygen permeativity. The oxygen permeation was measured as a function of oxygen activity gradient, membrane thickness (0.4-2.6 mm) and temperature (800 degrees C-950 degrees C). The oxygen self diffusion coefficient DO and the surface exchange coefficient k show Arrhenius-type behaviors with activation energies of similar to 50 and similar to 100 kJ/mol, respectively. The oxygen chemical diffusion coefficient D-chem and surface exchange coefficient k(chem), measured by conductivity relaxation, exhibit Arrhenius-type behaviors with activation energies of 62 and 104 kJ/mol, respectively. D-chem and k(chem) are related to D-O and k through the thermodynamic factor omega(O).