Surface Nanosegregation of Chemical Composition in Complex Oxides

A brief review of theoretical, experimental results in the field of surface nanosegregation of chemical composition of oxides (principal components), stimulated by temperature or other factors, is given. Experimental data, obtained exclusively for monocrystals in situ and post situ by Auger electron spectroscopy, X-ray electron spectroscopy, X-ray spectral microanalysis, and secondary-emission spectroscopy are considered. The model concepts assume a diffusion mechanism of segregation, and the theory parameters contain elastic constants and crystallochemical characteristics of substances. All the oxides investigated are divided into groups with different segregation degrees. The models allow prediction of the character of changes of the surface composition of oxides: segregate type and degree of nonstoichiometry.