Surface Instability in High Surface Area Complex Oxides: BaTiO3 Study

High quality BaTiO 3 powders that were synthesized with hydrothermal and solid state methods are characterized with respect to surface chemistry. Different characterization techniques are used to obtain a physical picture for the BaTiO 3 powders with respect to different synthesis routes and thermal histories. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS) are used to understand the BaTiO 3 powders after heat and humidity treatments. Formation of amorphous and crystalline BaCO 3 in local heterogeneous regions depletes the surrounding surface of Ba ions to create larger areas that are Ti-rich. BaCO 3 formation and adventitious carbon adsorption occur extremely quickly on the surface of crushed single-crystal BaTiO 3 powder, but for manufactured powders, the degree of carbonate formation and the impact on surface stoichiometry varies with thermal history.