Oxygen transport in the La2Ni1−xCoxO4+δ system

Oxygen isotopic exchange measurements of polycrystalline La2Ni1−xCoxO4+δ have been carried out for the 30%, 50%, 80% and 100% Co doped materials and both the oxygen tracer diffusion coefficient, D*, and surface exchange coefficient, k, determined. Each of the high Co content materials (x ≥ 0.5) was found to have higher diffusion and surface exchange coefficients than the previously reported parent compound La2NiO4+δ. Of greater interest are the relatively high diffusion coefficients calculated for the high cobalt content materials, particularly the La2Ni0.2Co0.8O4+δ and La2CoO4+δ materials over the temperature range 450-650 °C. As the surface exchange coefficients for these materials are also high these materials then meet the D*k product requirement of 10− 14 cm3 s− 2 for cathodes at the low temperature of ∼470 °C.