XPS investigation of surface properties of Ba(1-x)SrxTiO3 powders preparedby low temperature aqueous synthesis

Barium titanate powders prepared by wet chemical routes are known to show l arge deviation from stoichiometry and contamination at surface, due to chem ical instability in solution at low pH values (< 9), and carbonates formati on after exposition to air. The surface composition of ceramic powders prep ared via rite low temperature Aqueous Synthesis (LTAS), with nominal formul a Ba(1-x)SrxTiO3 (x less than or equal to 0.1), have been investigated on p ressed pellets of as-prepared powders by X-ray photoelectron spectroscopy. BaCO3 content has been evaluated from Ba3d and Ba4d spectra. The total rela tive amount of carbonate has been measured by X-ray diffraction and compare d to that present on surface. From these data, the formation of BaCO3 by su rface reaction with the atmosphere or by bulk precipitation is discussed. ( C) 1999 Elsevier Science Limited. All rights reserved.