Optimizing the piezoelectric properties of Ba0·85Ca0·15Zr0·10Ti0·90O3·lead-free ceramics via two-step sintering

The two-step sintering of lead-free Ba0·85Ca0·15Zr0·1Ti0·9O3·(BCZT) ceramics was investigated as a way to enhance its piezoelectric properties. The variations in grain size as a function of the calcination and sintering conditions and its effect on performance is discussed. Results indicate that as the calcination and first-step sintering temperatures increased, grain size became large and was independent of the second sintering step. Large grains were responsible for the enhanced piezoelectric properties by causing lattice distortion, larger domains, and easy motion of domain walls. The BCZT ceramic calcined at 1200 °C and sintered at 1540 °C without holding and then cooled to 1400 °C and held at 1400 °C for 4 h exhibited optimal performance with the highest remnant polarization Pr ∼13.5 μC/cm2, the largest piezoelectric constant d33 ∼ 529 pC/N at room temperature, and the highest Curie temperature Tc ∼125 °C. Two-step sintering has been turned out to be an effective method to realize high-performance BCZT ceramics by microstructure optimization.