Effect of bismuth doping on dielectric, piezoelectric and ferroelectric properties of PZT ceramics

Bi₂O₃ doped lead zirconate titanate (PZT) ceramics were prepared by a conventional solid state process, and the doping effects on the phase structure, microstructure, dielectric and piezoelectric properties were also investigated. When a small amount of Bi₂O₃ (≤0·5 mol.-%) was added, the density of PZT ceramics increased. However, the addition of increasing amounts of Bi₂O₃ hindered the densification, resulting in a high porosity and small grain size. Also, when the amount of Bi₂O₃ added was more than 0·5 mol.-%, the structure of the ceramics transferred from a tetragonal to a rhombohedral phase. The addition of Bi₂O₃ up to a maximum of 0·5 mol.-% improved piezoelectric properties of the PZT ceramics remarkably, while keeping the d ₃₃ and k _p values reasonably high. The PZT doped with 0·5 mol.-%Bi₂O ₃ exhibited excellent piezoelectric properties: d ₃₃=429 pC N^-1 and k _p=0·62, and it obtained the best ferroelectric properties.