Characterization of rutile passivation layers formed on Magnéli-phase titanium oxide inert anodes

An ex situ characterization study has been performed on rutile passivation layers on inert anodes used for molten salt electrochemical studies. Rutile layer thicknesses were estimated using a number of ex situ methods, including laboratory and synchrotron X-ray diffraction and optical microscopy. The only phases in the anode detected by diffraction were the Magnéli phases (Ti_nO_2n−1, n = 5–6) of the unreacted anode and rutile (TiO₂), which forms on electrolysis. These measurements validate a previously developed in situ energy-dispersive X-ray diffraction analysis technique [Scarlett, Madsen, Evans, Coelho, McGregor, Rowles, Lanyon & Urban (2009). J. Appl. Cryst.42, 502–512].