Piezoelectric properties of undoped and titanium or barium-doped lead metaniobate ceramics

Ferroelectric materials with high Curie temperature are highly desirable to construct transducers for high temperature piezoelectric applications. Among the ferroelectric materials PbNb2O6 (PN) is one that display such characteristic. However, the fabrication of high density PN ceramics is very difficult, which limited the use in piezoelectric transducers. In this paper high density (∼95%) Ti- and Ba-doped PN ceramics were prepared through the conventional ceramic method. The electromechanical coefficients, such as coupling (k31, k33) and quality factors (Qm), were measured and compared in the investigated materials. The properties of “pure” PN were comparable to those observed in Ti- and Ba-modified PN ceramics. The addition of Ba to the PN ceramics decreased the Curie temperature (as compared to the pure PN), limiting the applicability in piezoelectric transducers for temperatures below 350 °C. On the other hand, the addition of titanium not only increases the Curie temperature, but also contributes to the increase of the densification of the PN ceramics. Results showed that Ti doped PN ceramics present a high potential to be used in high temperature applications as piezoelectric transducers.