Distribution of the iron dopant in barium titanate ceramic, determined by the scanning transmission electron microscope

The iron distribution in iron-doped BaTiO3 ceramic with an average grain diameter of 0.3 μm is measured in a scanning transmission electron microscope with a field-emission gun. The mass fraction of iron varies from grain to grain between 0.1 and 0.2%. Whereas the iron distribution within the grain is homogeneous, a boundary layer with a thickness of no more than 20 nm shows an increase in the iron concentration by an average of 0.4%. Possible iron distributions within the boundary layer and the relation between the measured iron distribution and the electrical properties of the ceramic are discussed.