Microstructure, Dielectric, and Piezoelectric Properties of Pb0.92Ba0.08Nb2O6-0.25 wt% TiO2 Ceramics: Effect of Sintering Temperature

In order to obtain dense PbNb2O6-based piezoelectric ceramics with a single orthorhombic ferroelectric phase, Ba, and excess Ti were doped into PbNb2O6 ceramics with the composition of Pb0.92Ba0.08Nb2O6-0.25 wt% TiO2 via a conventional solid-state reaction method. The ceramics were sintered at 1210 degrees-1300 degrees C. The effects of sintering temperature on the crystallite structure, microstructure, and dielectric and piezoelectric properties were studied in detail. All ceramics had shown a high relative density (>94%) and a single orthorhombic phase. The lattice parameters, grain size, and shape varied with changing sintering temperature. All ceramics exhibited a typical characteristic in ferroelectrics with normal paraelectric-ferroelectric phase transition at the Curie temperature. With increasing sintering temperature from 1210 degrees to 1300 degrees C, the Curie temperature decreased from 554 degrees to 523 degrees C, while the maximum dielectric constant increased. The change in dielectric properties with changing sintering temperature is associated with a competing effect among internal stress, porosity, and grain size. The ceramic sintered at 1260 degrees C possesses an excellent piezoelectric constant (d(33) = 82 pC/N), low mechanical quality factor (Q(m) = 20.52), low dielectric loss ( tan delta = 0.0062), and high Curie temperature (T-c=535 degrees C), presenting a high potential to be used in high-temperature applications as piezoelectric transducers.