Microstructure, dielectric properties and impedance spectroscopy of Ni doped CaCu3Ti4O12 ceramics

Abstract

Ni doped CaCu₃Ti₄O₁₂ ceramics (CaCu_3−xNi_xTi₄O₁₂, 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. CaCu_3−xNi_xTi₄O₁₂ 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 CaCu_2.9Ni_0.1Ti₄O₁₂ 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 CaCu_2.95Ni_0.05Ti₄O₁₂ 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.