Microstructures and dielectric properties of sol-gel prepared K-doped CaCu3Ti4O12 ceramics

K+ doped CaCu3Ti4O12 ceramics were prepared by the sol-gel method and sintered at different temperatures from 1040 °C to 1100 °C. The microstructures and various dielectric properties of Ca1-xKxCu3Ti4O12-δ ceramics were investigated. Results of XRD indicate that the Ca1-xKxCu3Ti4O12-δ samples exhibit a typical cubic structure. The grain size as well as the dielectric permittivity (ε’) increase obviously with the increasing sintering temperature. The dielectric permittivity and dielectric loss (tanδ) measurements show strong frequency dependence in all the samples. A ε’ value of about 2.3 × 104 and a low tanδ value of about 0.039 were observed at room temperature and 1 kHz in the Ca0.99K0.01Cu3Ti4O12-δ (CKCTO) ceramics sintered at 1060 °C for 8 h, showing better dielectric properties than pure CCTO. Dielectric relaxations were observed in ε′/tanδ-T curves which may be related to the IBLC effect.