Effects of sintering temperature on the internal barrier layer capacitor (IBLC) structure in CaCu3Ti4O12 (CCTO) ceramics

The formation of the internal barrier layer capacitor (IBLC) structure in CaCu3Ti4O12 (CCTO) ceramics was found to be facilitated by the ceramic heat treatment. Electrically insulating grain boundary (GB) and semi-conducting grain interior areas were characterized by impedance spectroscopy to monitor the evolution of the IBLC structure with increasing sintering temperature TS (975-1100 °C). The intrinsic bulk and GB permittivity increased by factors of ≈2 and 300, respectively and the bulk resistivity decreased by a factor of ≈103. These trends were accompanied by increased Cu segregation from the CCTO ceramics as detected by scanning electron microscopy and quantitative energy dispersive analysis of X-rays. The chemical changes due to possible Cu-loss in CCTO ceramics with increasing TS are small and beyond the detection limits of X-ray absorption spectroscopy near Cu and Ti K-edges and Raman Spectroscopy.