Identification of surface composition and chemical states in composites comprised of phases with fluorite and perovskite structures by X-ray photoelectron spectroscopy

► Cation rearrangement between the surface and bulk of grains was studied in composites. ► Surface of La0.6Sr0.4CoO3-CeO2 and La0.8Sr0.2MnO3-CeO2 composites is depleted in Ce. ► Ce4+ (major fraction) and Ce3+ cations are present at the surface or interfaces. ► Small fraction of CeO2 facilitates surface segregation of Co cations in composites. ► O 1s spectra vary with CeO2 content and chemical origin of transition metal cations.