Interface reactions in the NiO–SDC–LSGM system

The reactivity of NiO–SDC (samaria-doped ceria) anode material with a Sr- and Mg-doped lanthanum gallate (LSGM) electrolyte was studied by X-ray diffraction (XRD) and electrical measurements. It was found that a LaNiO3-based compound in hexagonal structure formed in binary powder mixtures of NiO and LSGM after firing at 1150°C. Reaction between SDC and LSGM was also observed. Several SDC peaks merged with the adjacent LSGM peaks during firing, and a SrLaGa3O7 compound was identified as a reaction product. Reaction between LSGM and SDC could cause more than 50% loss in the ionic conductivity of LSGM–SDC electrolytes sintered at 1350°C. The measured conductivity of an LSGM electrolyte with a NiO–LSGM anode prepared at 1350°C was extremely low, indicating that the LaNiO3-based new phase is highly insulating. The reaction between NiO and SDC was not so obvious in comparison with NiO–LSGM and SDC–LSGM binary mixtures.