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

Barium titanate powders prepared by wet chemical routes are known to show large deviation from stoichiometry and contamination at surface, due to chemical instability in solution at low pH values (< 9), and carbonates formation after exposition to air. The surface composition of ceramic powders prepared via rite low temperature Aqueous Synthesis (LTAS), with nominal formula Ba(1-x)SrxTiO3 (x less than or equal to 0.1), have been investigated on pressed pellets of as-prepared powders by X-ray photoelectron spectroscopy. BaCO3 content has been evaluated from Ba3d and Ba4d spectra. The total relative amount of carbonate has been measured by X-ray diffraction and compared to that present on surface. From these data, the formation of BaCO3 by surface reaction with the atmosphere or by bulk precipitation is discussed