Influence of zinc on electrical and microstructural properties of CaCu3Ti4O12 ceramics prepared by sol-gel process

Zn-substituted CaCu3Ti4O12 ceramics were prepared by the sol-gel method. Their microstructures and electrical properties were investigated. XRD patterns showed that the CaCu3-xZnxTi4O12 (CCZTO) (x = 0.00, 0.06, 0.10, 0.20) ceramics, after sintering at 1050 degrees C for 20 h, were single phase with no Cu-rich phase. SEM results indicated that the samples had smaller grain sizes than those synthesized by traditional solid-state reaction methods. The dielectric and varistor properties of CCZTO were analyzed by a precision impedance analyzer and a varistor tester, respectively. According to Debye's equation, which states that the smaller the leakage current, the smaller the dielectric loss will be in the low-frequency region, we were able to roughly predict the relative value of the dielectric loss at low frequency by the leakage current. The best overall properties were obtained for x = 0.06 (CaCu2.94Zn0.06Ti4O12), which has several prospective applications, such as low voltage varistor switchings, gas-sensing devices, and varistor-capacitor double property devices. (C) 2012 Elsevier B.V. All rights reserved.