Interaction of barium titanate powders with an aqueous suspending medium

Characterisation by SEM, TEM and XPS of BaTiO3 powders that have been expos ed to water provides an assessment of the extension of their interaction wi th the suspending medium. Ba2+ ions are released into the aqueous solution when powder suspensions are prepared, as detected by atomic absorption spec troscopy, but it appears that their presence in the aqueous medium is due t o dissolution of BaCO3 present in the powders as an impurity. No changes in morphology of the powders or composition of the surface were observed, a p art from precipitation of BaCl2 on the surface of the particles when the pH was lowered with HCl. However, a similar to 20 nm layer depleted in Ba2+ d evelops at the sup face of undoped sintered materials after exposure to wat er, as a result of the partial hydrolysis of the BaTiO3, which affect in le ss extent to Nb-doped sintered material. (C) 1998 Elsevier Science Limited. All rights reserved.