The effects of microstructure on the dielectric, ferroelectric and impedance properties of 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 ceramics

0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 (BCZT) ceramics with average grain sizes from 3.26 to 18.15 mu m were synthesized by adjusting the sintering temperature in the solid-state-reaction process. The effects of various grain sizes on the dielectric, ferroelectric, and impedance properties of BCZT ceramics were studied, and the liquid phase in the grain boundary was observed. When a solid solution exists in the grain boundary, both the maximum dielectric constant epsilon max and loss tangent tan delta are affected by the competition between the grain size effect and liquid phase in the grain boundary morphology. The energy storage efficiency increases and the energy density decreases owing to the improved compactness and hindered grain boundary conduction. The contributions of grain and grain boundary are demonstrated by two arc curves in impedance spectra. The effects of different grain boundary morphologies on the electrical properties of BCZT ceramics were quantitatively obtained by high-temperature impedance patterns and DC conductivity fluctuations. These results help to prepare different tar-geted functional ceramics by designing specific microstructures.