Comparing depth profiling of oxide scale on SOFC interconnect-materials using ToF-SIMS with 69Ga+, Bi3+/Cs+ and C60+/C602+ as primary and sputter ions

Abstract

Oxide scale cross-sections of CeO2 coated FeCr based solid oxide fuel cell interconnect materials were examined using secondary ion mass spectrometry (SIMS) depth profiling. A duplex spinel∶chromia scale was formed after 1 h at 850°C. Ti and ceria were observed between these layers. Additionally, minor concentrations of Mn, Si and Nb were observed at the oxide/metal interface. Furthermore, Al and Ti were concentrated primarily in the metal surface close to the oxide/metal interface. Secondary ion mass spectrometry sputter depth profiles using different ion sources; 69Ga+, Bi3+/Cs+ and C60+/C602+ were compared with TEM oxide scale cross-section and field emission gun–Auger electron spectroscopy depth profiling. Secondary ion mass spectrometry depth profiling with 69Ga+, Bi3+/Cs+ showed decreased secondary ion yields in the metallic matrix. This decrease could be avoided using oxygen flooding. The C60 cluster ion depth profiles were less sensitive to type of matrix and gave the best correspondence to the TEM cross-section. However, the impact energy has to be high enough to avoid carbon deposition.