RESTRUCTURING OF THE SURFACE REGION IN SRTIO3

The combination of x-ray diffraction analysis with surface sensitive t echniques reveals a chemical inhomogeneity in the surface region of mo nocrystals of SrTiO3 prepared under low and high partial pressure of o xygen at elevated temperatures. A solid state reaction leads to the fo rmation of a multilayer-type structure. For oxidized crystals we obser ve AO-rich Ruddlesden-Popper phases at the surface and Magnelli phases of Ti in deeper layers of the surface region. The order of the layere d structure is reversed for the reduced crystals with Ti-oxides of dif ferent oxidation levels at the surface and Ruddlesden-Popper phases in lower parts of the surface region. It is argued that this restructuri ng influences the electrical properties of SrTiO3.