Preliminary EELS and EDS analyses of CaCu3Ti4O12 ceramics, sintered for 3 and 24h at 1100C in air, suggested that there were differences in the composition and valence of Cu and Ti at grain boundaries, as compared with the bulk composition. For 3h sintering, a change was observed in the Cu valence and for the 24h 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.

Characterisation of Grain Boundaries in CaCu3Ti4O12 Using HREM, EDS and EELS. C.C.Calvert, W.M.Rainforth, D.C.Sinclair, A.R.West: Journal of Physics - Conference Series, 2006, 26, 65-8