Combining high temperature electrochemistry and time of flight secondary ion mass spectrometry: Quasi in situ study of lanthanum strontium chromate manganate electrodes

Abstract

Time of flight secondary ion mass spectrometry (TOF-SIMS) is a well-established technique for the chemical surface and depth analysis of inorganic functional materials. Here we report in detail on the changes in the surface composition of a solid oxide fuel cell (SOFC) thin film model electrode, namely lanthanum strontium chromate manganate (LSCrM, La0.64Sr0.36Cr0.68Mn0.35O3−δ), on yttria stabilised zirconia (YSZ) as solid electrolyte, upon electrochemical polarisation. The electrochemical experiments were performed in the TOF-SIMS analysis chamber allowing fast analysis directly afterwards. Changes in the electrode surface composition occur already after sample annealing in air, i.e. strontium and lanthanum diffuse to the top of the LSCrM electrode and onto the free YSZ surface. By applying either a cathodic or an anodic potential to the electrode, enrichment or depletion of the different cation constituents on both the LSCrM and free YSZ surface were observed. These redistribution phenomena are partly reversible several times upon switching the electrical potential of the LSCrM electrode.