Electrical Conduction and Dielectric ...

CaCu3Ti4O12 (CCTO) ceramic was synthesized by the spark plasma sintering (SPS) technique. The single-phase composition of CCTO was confirmed by X-ray diffraction. The measurements of the dc electrical conduction and dielectric properties show that the dielectric constant, dielectric loss and leakage current density decrease with the thickness decreasing, meanwhile the variation range of the dielectric constant also narrows greatly in the frequency range between 1 kHz and 1 MHz. In addition, the increase of the nonlinear coefficient for the dc current density–electric field strength curves and the enhanced resistivity both in grain and at grain boundary are also observed. These results can be attributed to the formation of a larger amount of oxygen vacancies near ceramic surface due to the reducing reaction from carbon in the sintering process.