Although SFO showed better ODH of ethane over LFO at the conditions tested, a secondary strontium-zirconia phase appears to have formed in the SOFC anode as observed by the accumulation of strontium at the anode-electrolyte interface (Figure ). Convex hull analyses (Figure ) via Density Functional Theory showed that single phase structures of Sr-Zr-O are possible, with SrZrO3 being the most stable at 0K . In addition, the XRD collected on SFO (Figure ) shows a small peak at 2 of ~30°, which would be the most intense peak in the diffractogram for SrZrO3. Experimental phase diagrams suggest other possible compositions based on temperature and molar ratio, therefore the exact composition of the secondary phase requires further analysis. Nonetheless, the Sr-Zr-O phase formed is possible due to the sintering temperature and presence of Sr-and Zr-based species at the interface between SFO and the zirconium-based electrolyte. Therefore, alternative processing conditions or perovskite chemistry could eliminate this significant interaction between the electrode and the zirconium electrolyte.