Phase Formation and Enhanced Dielectric Response of Y2/3Cu3Ti4O12 Ceramics Derived from the Sol-Gel Process

Y2/3Cu3Ti4O12 (YCTO) ceramics were successfully synthesized by sol-gel method (SG) and solid-state method (SS), respectively. The optimized processing parameters for the syntheses of precursor powders by sol-gel process were determined as follows: the Ti(OC4H9)(4) concentration was 0.50mol/L, the CH3COOH volume was 8mL, and the volume percentage of H2O was 11.2%. Particularly, on the basis of XRD and TG-DSC analyses, the phase formation temperature of YCTO-SG was at least 100 degrees C lower than that of YCTO-SS. YCTO-SG ceramics sintered at 1060 degrees C for 25h showed fine-grained microstructure, and higher dielectric constant (epsilon approximate to 5.24x10(4)) at 1kHz compared to YCTO-SS ceramics (epsilon approximate to 0.93x10(4)). The higher dielectric constant of the YCTO-SG ceramics was attributed to the grain size effect. Furthermore, the YCTO-SG ceramics showed a distinct high-temperature (>300 degrees C) relaxor-like behavior. According to the calculated activation energy value, the single ionization of oxygen vacancies was responsible for the conduction and dielectric anomaly behaviors of YCTO-SG ceramics.