Microstructure and dielectric properties of Na and Ni co-substituted CaCu3Ti4O12 ceramics with high dielectric constant and low loss

Abstract

Preparation of Na and Ni co-substituted CaCu3Ti4O12 (CCTO) ceramics through sol-gel method is carried out to enhance the dielectric properties. On the morphology and dielectric properties of CCTO ceramic, the effects of Na and Ni co-substitution are investigated. The results demonstrate that at room temperature, Na and Ni co-substituted Ca0.993Na0.007Cu2.95Ni0.05Ti4O12 exhibits significantly increased grain size and consequently a high dielectric constant exceeding 12000 across a broad frequency range (1–105 Hz). Meanwhile, its dielectric loss is reduced to 0.016 at 1 kHz, a phenomenon that can be ascribed to the raised resistance and activation of grain boundary. Furthermore, Ca0.993Na0.007Cu2.95Ni0.05Ti4O12 also yields a breakdown field strength of 2.3 kV/cm. The giant dielectric response can be explained by the internal barrier layer capacitor model. These excellent comprehensive performances not only contribute to obtain simultaneously low dielectric loss and high breakdown strength for CCTO ceramics with high dielectric constant, but also can facilitate the practical application of CCTO ceramics in advanced capacitors.