Solid State Processing of BCZT Piezoceramics Using Ultra Low Synthesis and Sintering Temperatures

Lead-free (Ba0.92Ca0.08) (Ti-0.95 Zr-0.05) O-3 (BCZT) ceramics were prepared by a solid-state route (SSR) using ultra-low synthesis (700 degrees C/30 min and 700 degrees C/2 h) and sintering temperatures (from 1150 degrees C to 1280 degrees C), due to prior activation and homogenization by attrition milling of the starting high purity raw materials for 6 h before the synthesis and of the calcined powders for 3 h before the sintering. The comparison of the thermal analysis of the mixture of the starting raw materials and the same mixture after 6 h attrition milling allowed to evidence the mechanisms of activation, resulting in a significant decrease of the perovskite formation temperature (from 854 degrees C down to 582 degrees C). The secondary phases that limit the functional properties of the ceramic and their evolution with the sintering conditions were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), which allowed the design of a two-step sintering method to eliminate them. A pure tetragonal BCZT perovskite phase (P4mm, c/a = 1.004) and homogeneous ceramic microstructure was obtained for synthesis at 700 degrees C for 2 h and sintering with the use of a two-step sintering treatment (900 degrees C for 3 h and 1280 degrees C for 6 h). The best electromechanical properties achieved were d(33) = 455 pC/N, k(p) = 35%, Q(m) = 155.

Automated summary

Lead-free (Ba0.92Ca0.08)(Ti-0.95 Zr-0.05) O-3 (BCZT) ceramics were successfully prepared using solid-state route and low-temperature synthesis. The activation and homogenization process significantly decreased the perovskite formation temperature. The elimination of secondary phases was achieved through a two-step sintering treatment, resulting in a pure phase BCZT ceramic with excellent electromechanical properties.