Effect of Zr doping on dielectric properties and grain boundary response of CdCu3Ti4O12 ceramics

Abstract An effective strategy to improve the dielectric properties of CdCu3Ti4O12 ceramics was proposed via doping with Zr4+ substituting in Ti4+ sites using the sol-gel method. SEM images of samples with high densification show a fine-grained and uniform-sized microstructure, and the average grain sizes of the ceramics decrease with increasing content of Zr doping. A proper amount of Zr substitution in the CdCu3ZrxTi4-xO12 ceramics was of great benefit to depress the dielectric loss tangent. A CdCTO-Zr05 ceramic exhibited a relatively low dielectric loss tangent value of 0.048 at 1 kHz. Meanwhile, the improved grain boundary response and dielectric properties were closely linked to the enhanced grain-boundary resistance. Data obtained based on complex impedance spectroscopy assessments demonstrated that the giant dielectric permittivity of the samples should be ascribed to the internal barrier layer capacitor (IBLC) effect. Overlapped spectroscopy of scaling behaviours indicated that the electric conduction and dielectric relaxation mechanisms shown in CdCu3ZrxTi4-xO12 ceramics are the same in this work.