Reestablishment of dielectric and nonlinear properties for Bi3+ doped CaCu3Ti4O12 ceramics prepared by reduction-reoxidation method

Multilayer ceramics with base metal internal electrodes should be prepared through reduction sintering to avoid the oxidation of the electrodes, followed by a reoxidation process. In this study, Ca 1- x Bi-x Cu3Ti (4- x /4) O-12 + 0.03 BN ceramics were fabricated using the reduction-reoxidation method and the reestablishment of dielectric and nonlinear characteristics was investigated. It was observed that the dielectric and nonlinear properties depended crucially on the grain size and the second phases at the grain boundaries. The reoxidation behavior was remarkably improved when grain growth was suppressed and second phases were introduced. Optimal electrical properties were obtained for samples with x = 0.1 sintered at 1050( degrees)C and reoxidized at 800( degrees) C. The dielectric loss decreased to a value of about 0.14, while the permittivity remained a relatively large value of about 9.9 x 10(3) at 10(3) Hz. Additionally, the nonlinear coefficient and breakdown field were improved to a value of 2.2 and 981.8 V/cm, respectively. This study illustrates an efficient approach to enhance the reestablished dielectric and nonlinear properties for Bi3+ doped CaCu3Ti4O12-based ceramics fabricated through the reduction-reoxidation method.