Influence of the processing rates and sintering temperatures on the dielectric properties of CaCu3Ti4O12 ceramics

The stoichiometric CaCu 3 Ti 4 O 12 pellets were prepared by the solid state synthesis. X-ray diffraction data revealed the tenorite CuO and cuprite Cu 2 O secondary phases on the unpolished CaCu 3 Ti 4 O 12 samples regardless of the heating rates. Also, the dielectric constant marked the highest for the CaCu 3 Ti 4 O 12 sample sintered at the lowest heating rate (1°C/min), which was explained by the increased grain conductivity due to the cation reactions. On the other hand, Cu 2 O phase was found only on the unpolished CaCu 3 Ti 4 O 12 sample sintered over 1100°C and those are considered as the remains reduced from the CuO phase. The higher sintering temperature showed the increased dielectric constant and the loss tangent of the CaCu 3 Ti 4 O 12 samples, and this result could be interpreted by the impedance measurement data. The relationship between the processing condition and the dielectric properties was discussed in terms of the cation non-stoichiometry and the defect chemistry in CaCu 3 Ti 4 O 12 .