Enhanced dielectric properties of Ca0.9Sr0.1Cu3-yZnyTi4-xBxO12 ceramics by modifying grain boundary response

Ca0.9Sr0.1Cu3-yZnyTi4-xBxO12 ceramics (0.01 <= x <= 0.07, y = 0 and 0.05) were prepared using the citrate precursor process and sintered at 1100 degrees C for 3 h. X-ray diffraction (XRD) has confirmed that CaCu3Ti4O12 ceramics with single phase can be prepared for a short-term sintering. The results of XRD and Raman reveals the existence of secondary phase as x = 0.07. The energy dispersive spectrometer confirms the presence of Cu-rich phase at grain boundary, which leads to a weakened dielectric properties. B3+ doping can speed the grain growth, whereas Zn2+ doping decreases grain size slightly and high dense microstructures were observed. The introduction of Zn2+ leads to an increase of grain boundary resistance, a decrease of dielectric loss and an enhancement of frequency stability of dielectric properties. Enhanced dielectric properties with dielectric constant of similar to 13410 and dielectric loss of similar to 0.038 were observed for the sample at x = 0.04 and y = 0.05. Moreover, the nonlinear electrical characteristics are enhanced with proper concentration of Sr, B and Zn additions. The present results indicate that the improved dielectric properties of doped CCTO ceramics are mainly attributed to the improved microstructure and the modified grain boundary response.