Relationship among the phase equilibria, microstructures, and dielectric properties of CaCu3Ti4O12 ceramics via different sintering time

The structure–property relationship of the CaCu3Ti4O12 ceramics processed via conventional solid-state method was studied in terms of the different processing conditions. X-ray diffraction patterns of the tenorite CuO and cuprite Cu2O secondary phases found on the unpolished and polished surfaces of CaCu3Ti4O12 were explained by the reduction/reoxidation reaction as a function of sintering time. Based on the microstructures, grain growth of CaCu3Ti4O12 continued from 0.5 to 4 h sintering while the further growth was limited to the small-sized grains after 8 h sintering. Also, WDS data indicated the Cu-deficient and Ti-excessive stoichiometry of CaCu3Ti4O12 on both outer and inner regions regardless of sintering time. The change of dielectric constant and tan δ were shortly discussed with regard to the secondary phases and the microstructures of the different sintering hours.