Preparation and characterization of core-shell structured TiO2-BaCO3 particles

Preparation of core-shell structured TiO2-BaCO3 particles as precursor of BaTiO3 genesis, proceeds using a two step procedure, by first coating the TiO2 core by Ba(OH)(2) shell followed by conversion of the shell region with CO2 gas by the formation of BaCO3. Straightforward experimental results reveal environmental scanning electron microscopy (ESEM) and scanning transmission electron microscopy (STEM) as suitable methods for analytical characterization of the core and shell regions from individual TiO2-BaCO3 grains. Evidence of coating the whole ensemble of TiO2 particles is possible using Photo Electro Motive Force (Photo EMF, PEMF) measurements. This method is able to indicate very sensitively changes of surface properties of TiO2 after coating with Ba(OH)(2) and BaCO3, respectively. PEMF measurements were used for the first time with concern to this topic. (C) 2001 Editions scientifiques et medicales Elsevier SAS. All rights reserved.