Electron probe for unequivocal surface characterization and surface defect engineering of energy materials : example of BaTiO3

Surface properties of crystalline solids and the related defect disorder of the surface layer have a critical effect on the reactivity and performance of materials, including energy materials. It is shown here that a high-temperature electron probe enables unequivocal surface characterization of energy oxide materials in a gas/solid equilibrium, including the affinity-related charge transfer and segregation-affected defect disorder. As an example, this work considers in situ surface monitoring of barium titanate at elevated temperatures during oxidation to determine a quantity (described as work function) that is reflective of the chemical potential of electrons during gas/solid reactions. The probe enables insight into local surface structures and opens up new fields of surface defect chemistry and surface defect engineering of materials for clean energy conversion.