Characterisation of Grain Boundaries in CaCu₃Ti₄O₁₂ using HREM, EDS and EELS

Preliminary EELS and EDS analyses undertaken on CaCu₃Ti₄O₁₂ ceramics, sintered for 3 and 24 hrs at 1100°C in air, have suggested that there are differences in the composition and valence of the Cu and Ti at grain boundaries as compared with the bulk composition. For the 3 hour sinter a change was observed in the Cu valence and for the 24 hour a change in both Ti and Cu valences was detected. This variation in composition may explain the electrical properties of high permittivity at room temperature exhibited by these ceramics.