Effects of Bi2O3 additive on sintering process and dielectric, ferroelectric, and piezoelectric properties of (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 lead-free piezoceramics

Abstract Lead-free Ba 0.85 Ca 0.15 Zr 0.1 Ti 0.9 O 3 (BCZT) piezoceramics with Bi 2 O 3 additive were synthesized using solid-state ceramic processing. Various amounts of Bi 2 O 3 (0.05, 0.1, 0.5, and 1.0 mol%) were added after calcination, milled, compacted, and sintered with no compensation at A- or B-sites. Addition of up to 0.5 mol% Bi 2 O 3 was found to greatly enhance the densification and increase the piezoelectric properties, while higher amounts decreased the grain size and induced relaxor-like electrical behavior, obeying the Vogel-Fulcher model. The highest properties were obtained for the BCZT with 0.1 mol% Bi 2 O 3 sintered at 1350 °C: d 33  = 325 pC/m, d 33 *  = 509 pm/V (at 3 kV/mm), k p  = 0.42, and P r  = 10.4 μC/cm 2 . The microstructure, phase composition, and local structure were investigated by scanning electron microscopy, X-ray diffraction, and Raman spectroscopy. The appearance of the A 1g vibration mode in the Raman spectra and the shift of diffraction peaks to lower 2θ values indicate the incorporation of Bi 3+ into the B-site of the perovskite BCZT structure.