Impact of fast microwave sintering on the grain growth, dielectric relaxation and piezoelectric properties on Ba0.18Ca0.02Ti0.09Zr0.10O3 lead-free ceramics prepared by different methods

The impact of microwave sintering on the grain growth, dielectric relaxation and piezoelectric properties of Ba0.82Ca0.18Ti0.90Zr0.10O3 (BCTZ) lead-free ceramics prepared by different methods (solid-state and hydrothermal) was investigated in this study. A combination of XRD, SEM, impedance analyzer, ferroelectric analyzer and d33 meter techniques was used. A higher solid solubility of CaTiO3 in hydrothermal samples was identified from XRD patterns. For the BCTZ prepared by solid state method, high permittivity was obtained, while those prepared by hydrothermal exhibited excellent ferroelectric and piezoelectric properties. In the SEM micrographs, hydrothermal samples showed a relatively smaller and homogeneous grain size (∼100 nm) than solid-state samples (∼800 nm), and nano-ceramics were obtained by this method. A model was established to investigate the differences in grain growth between the two samples during the microwave sintering process. Also, BCTZ ceramics prepared by hydrothermal possessed a better frequency dispersion and thermally activated relaxation.