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

Abstract

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 °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 ~13410 and dielectric loss of ~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.