Surface chemistry of BSCF material after Ar plus ion treatment and at elevated temperatures

摘要

The microstructure and electronic structure of barium strontium iron cobalt oxide of nominal composition Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) was studied using Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Chemical states of the iron, cobalt, barium and strontium core levels were identified both from the surface and bulk material. The influence of low energy Ar + ion bombardment on the electronic structure of the sample was studied. The SEM and XPS studies were executed at room temperature and after annealing in situ at temperatures up to 700 degrees C. The changes of the atomic concentration were found and were attributed to ion and thermal treatment. The clear differences of morphology were found for polished and in situ annealed surfaces. The loss of oxygen during cleaning by Ar + ion sputtering was determined. The valencity of Co2+ was detected on the surface. The changes of atomic concentration of barium in relation to strontium indicated higher mobility of barium at elevated temperatures. The changes in conductivity of the surface layer upon Ar + ion treatment and annealing at 700 degrees C was deduced from the valence band spectra.