Changes in the morphology and the composition of the Ag|YSZ and Ag|LSM interfaces caused by polarization

The behavior of silver as the SOFC cathode material at 600 °C was investigated. Ag|YSZ|Pt, Ag|LSM|Pt and Ag|LSM|GDC|Pt systems were polarized for 24 hours applying bias of up to 0.5 V. Changes in the morphology and the composition of the electrolyte surface on the cathodic side were examined by the Scanning Electron Microscopy, Energy Dispersive X Ray Spectroscopy, Atomic Force Microscopy and X-ray Photoelectron Spectroscopy. Silver dendrites arose around the contact in the Ag|YSZ|Pt and Ag|LSM|GDC|Pt cells but not in the Ag|LSM|Pt system. No changes were observed in the composition and morphology of YSZ surface below the silver cathode except the partial reduction of Zr4+ and/or formation of oxygen vacancies leading to the negative shift in the Zr 3 d binding energy. In the case of the Ag|LSM|GDC|Pt cell partial decrease of the concentrations of the surface Mn species with higher than + 4 oxidation state and the surface Sr species was observed.