Effects of Nb doping in lead barium zirconate ceramics

The electromechanical properties of ferroelectric materials can be modified by doping in order to meet the requirements for various applications. This is well known in PZT ceramics, in which even a very small amount of the dopant element affects macroscopic properties and makes the ferroelectric hard or soft. We investigate whether hard and soft behavior occurs also due to doping of PBZ, which, to the best of our knowledge, has not been studied before. Pb_0.77Ba_0.23ZrO₃ ceramics with 1-mol%-PbO-excess have been prepared with various Nb-dopant concentrations between 0.05 and 2 mol% by the mixed-oxide route. The densification behavior and the microstructural development, as well as ferroelectric, dielectric, and piezoelectric proper-ties were measured and analyzed. The phase analysis of the sintered solid solutions revealed sin-gle-phase perovskite for all concentrations. The results showed a different relative density and grain size dependence for samples containing >0.5 mol% additives compared to samples with <;0.5 mol% Nb. Nb doping influenced significantly the electrical characteristics. Softening and a very marked increase in the dielectric and piezoelectric characteristics were obtained for low con-centrations of Nb⁺⁵. The influence of the dopants and associated defects on the physical and electrical characteristics was investigated and well correlated.