Effect of the oxidizing atmosphere on the microstructure and dielectric properties of CaCu₃Ti₄O₁₂ ceramics

CaCu₃Ti₄O₁₂ ceramics were synthesized by using the solid-state reaction method, and the roles of heat-treatment in the oxidizing atmosphere on the microstructure and dielectric properties were investigated in this work. It is indicated that after heat-treatment in the oxidizing atmosphere, the dielectric constant is decreased slightly and the dielectric loss tangent is effectively suppressed to 0.03-0.04. In the temperature range of 183-273 K, the dielectric loss is composed of conductance loss and two relaxation loss peaks. It is worth noting that the conductance loss at low frequency is reduced obviously. The result impedance spectra analysis reveals that the grain boundary resistance of CaCu₃Ti₄O₁₂ ceramics is boosted from 1.8×10⁴ Ω to 8.6×10⁴ Ω at 393 K. Furthermore, the results from volt-ampere characteristics (J-E) exhibit that the breakdown field and nonlinear coefficient of CaCu₃Ti₄O₁₂ ceramics are increased from 226 V/mm and 3.52 to 397 V/mm and 4.51, respectively. The barrier height is also increased from 0.56 eV to 0.63 eV.