Segregation phenomena in thin films of BaTiO3

The near-surface region in perovskite bulk crystals is known to be subject to segregation processes at elevated temperatures which can lead to the for mation of non-perovskite phases. We have addressed the question whether ana logue phenomena may occur in thin films, Thin films of BaTiO3 prepared by d ifferent methods (PLD, CSD) and heat-treated in the temperature range of 70 0 degreesC-1000 degreesC are characterised by surface analytical methods an d microanalysis (AFM, SIMS, XPS). Our studies reveals dramatic changes in t he surface morphology and in-depth elemental distribution suggesting a chem ical restructuring comparable to the effects known for single crystalline B aTiO3. Possible driving forces for the observed segregation phenomena are d iscussed taking into account specific properties of the thin films.