Microstructure, dielectric properties and impedance spectroscopy of Ni doped CaCu3Ti4O12 ceramics
Ni doped CaCu3Ti4O12 ceramics (CaCu3−xNixTi4O12, x = 0, 0.05, 0.1, 0.2) were prepared by a sol–gel method and the influence on the microstructure, dielectric properties and impedance spectroscopy has been investigated. CaCu3−xNixTi4O12 ceramics can cause a remarkable increase in the grain size and exhibit a very high dielectric constant (ε′) over a wide frequency range at room temperature. The ε′ value of the CaCu2.9Ni0.1Ti4O12 ceramic sintered at 1060 °C for 8 h was between 7.1 × 104 and 9.6 × 104 over the frequency range of 20 Hz to 100 kHz. Besides, a very low dielectric loss (tan δ) of 0.025 was observed for the CaCu2.95Ni0.05Ti4O12 ceramic sintered at 1060 °C for 8 h with ε′ ∼ 4.2 × 104 at about 1 kHz. These results indicate that Ni doping at the Cu site may improve the dielectric properties of CaCu3Ti4O12. The giant dielectric response behavior can be attributed to the internal barrier layer capacitance (IBLC) effect.