Influence of the processing rates and sintering temperatures on the dielectric properties of CaCu_3Ti_4O_(12) ceramics

摘要

The stoichiometric CaCu_3Ti_4O_(12) pellets were prepared by the solid state synthesis. X-ray diffraction data revealed the tenorite CuO and cuprite Cu_2O secondary phases on the unpolished CaCu_3Ti_4O_(12) samples regardless of the heating rates. Also, the dielectric constant marked the highest for the CaCu_3Ti_4O_(12) sample sintered at the lowest heating rate (1℃/min), which was explained by the increased grain conductivity due to the cation reactions. On the other hand, Cu_2O phase was found only on the unpolished CaCu_3Ti_4O_(12) sample sintered over 1100℃ 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_3Ti_4O_(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_3Ti_4O_(12).