Improvement on dielectric properties of CaCu3Ti4O12 ceramics by heat treatment in rich oxygen atmosphere

CaCu₃Ti₄O₁₂ ceramics were synthesized by using the solid-state reaction method, and the roles of the heat treatment on the microstructure and dielectric properties were investigated. It is indicated that no second phase is found after heat treatment. At room temperature, 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 of CaCu₃Ti₄O₁₂ ceramics is composed of conductance loss at low frequency and two relaxation loss peaks at high frequency. It is worth noting that the conductance loss at low frequency is reduced apparently by the heat treatment. Furthermore, the results of 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 Schottky barrier height of CCTO ceramics is boosted from 0.56 eV to 0.63 eV.