Decomposition kinetics of CaCu3Ti4O12

摘要

Various compositions of CaCu3+xTi4+yO12 ceramics based on the cation stoichiometry (x = −0.06, 0, +0.06; y = −0.08, 0, +0.08) were prepared via conventional solid state method. From the XRD data, CuO phases were found on the surface layers of all non-stoichiometric CCTOs. On the other hand, Cu2O phase was detected on the inner layers of Cu- and Ti-excessive CCTO which yielded low values of the dielectric constant (K). The Cu- and Ti-deficient CCTO showed the improvement of both K and tan δ, which can be explained by the lower grain resistivities compared to stoichiometric CCTO by the impedance spectroscopy. Further results from the cooling rate control and different sintering conditions of the stoichiometric CCTO are discussed in terms of the relationship between phase equilibria of CuO and Cu2O and the dielectric properties.