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

Preparation of core-shell structured TiO2-BaCO3 particles as precursor of B aTiO3 genesis, proceeds using a two step procedure, by first coating the Ti O2 core by Ba(OH)(2) shell followed by conversion of the shell region with CO2 gas by the formation of BaCO3. Straightforward experimental results rev eal environmental scanning electron microscopy (ESEM) and scanning transmis sion electron microscopy (STEM) as suitable methods for analytical characte rization of the core and shell regions from individual TiO2-BaCO3 grains. E vidence of coating the whole ensemble of TiO2 particles is possible using P hoto Electro Motive Force (Photo EMF, PEMF) measurements. This method is ab le to indicate very sensitively changes of surface properties of TiO2 after coating with Ba(OH)(2) and BaCO3, respectively. PEMF measurements were use d for the first time with concern to this topic. (C) 2001 Editions scientif iques et medicales Elsevier SAS. All rights reserved.