Surface behavior of Sr-doped lanthanide perovskites

It is well known that the composition and the surface behavior of the elements influence on the catalytic activity of bulk catalysts and the ceramic membranes. The scope of the present work is to investigate the surface composition and evolution as a function of the temperature and oxygen partial pressure. Mixed conducting lanthanum containing ceramic samples with general formula La1−xSrxCo0.8Fe0.2O3−δ have been objects of investigations. Monitoring of perovskite surface is carried through ESCA-XPS (X-ray photoelectron spectroscopy). The detailed XPS survey spectra, valence band region spectra, partial core level spectra of the La, Sr, Co and Fe ions as well as O1s peak positions and behavior of the anion subnetwork are presented and discussed. The XPS experiments are carried out as function of oxygen partial pressure, thermal treatment procedure and the amount of the Sr-alkaline-earth heterovalent structural substitution. The 3d-electronic structure, surface O1s evolution and some local interactions are discussed in details.