Sintering Effects on Dielectric Properties of Zn-Doped CaCu3Ti4O12 Ceramic Synthesized by Modified Sol-Gel Route

CaCu2.90Zn0.10Ti4O12 ceramic was synthesized by a novel semi-wet route and calcined at 800 degrees C in air for 8 h. The obtained powder was divided into three parts and sintered in air at 950 degrees C for 6 h, 8 h, and 12 h, separately. XRD results confirmed the single phase formation of all the sintered samples with similar cubic structure of CaCu3Ti4O12 (CCTO). Scanning electron micrographs of the CaCu2.9Zn0.1Ti4O12 ceramic sintered for 6 h shows bimodal grain size distribution. Increasing the sintering time significantly promotes the grain growth and microstructural densification. The sintering duration was found to have tremendous influence on microstructure and dielectric properties of CaCu2.90Zn0.10Ti4O12 ceramic. The CaCu2.9Zn0.1Ti4O12 ceramic sintered for 12 h exhibited high dielectric constant epsilon(r) similar to 5971 at 1 kHz and room temperature. It is found that epsilon(r) is independent at high frequency and weakly dependent on temperature.