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 (epsilon') over a wide frequency range at room temperature. The epsilon' value of the CaCu2.9Ni0.1Ti4O12 ceramic sintered at 1060 degrees C for 8 h was between 7.1 x 10(4) and 9.6 x 10(4) over the frequency range of 20 Hz to 100 kHz. Besides, a very low dielectric loss (tan delta) of 0.025 was observed for the CaCu2.95Ni0.05Ti4O12 ceramic sintered at 1060 degrees C for 8 h with epsilon' similar to 4.2 x 10(4) 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.