Impact of the microstructure on the functional properties of (Ba,Ca)(Ti,Zr)O3 ceramics

One of the most promising BT-based materials for piezoelectric applications is the pseudobinary ferroelectric (1-x)Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 (BCTZ) (x is the molar percent of BCT). In the present paper, we present preparation and functional characterisation of Ba0.85Ca0.15Ti0.90Zr0.10O3 ceramics with grain size larger than 1 ?m. The powders were prepared by the conventional solid-state route starting from fine precursor powders and calcined at 1000°C/4 hours. Dense ceramics (relative density above 94-98%) with different grain size were obtained by sintering the resulted powders at temperatures between 1400-1500°C for different times (from 0.2-24 hours). The grain size of ceramics determined from SEM images were between 2 ?m for the samples sintered at 1400C/2h to 27 ?m for the samples obtained at 1500°C/24h. The evolution of polar order and phase transitions with grain size has been studied using dielectric permittivity measurements at 1Hz- 1MHz between 25 and 150°C. The high field dielectric properties (dc-tunability) show a slight modification with grain size. The presented data provide a complete picture of the size effect dependence of functional properties in Ba0.85Ca0.15Ti0.90Zr0.10O3 ceramics. Acknowledgment: This paper was performed during ECOST-STSM-MP1308-191116-081333.