The role of Nb2O5 polymorphs on processing–structure–property relationship in lead-based perovskite 0.5Pb(Yb1/2Nb1/2)O3-0.5PbTiO3 piezoceramics

Abstract

Lead-based niobate piezoceramics with perovskite structure exhibit a wide range of superior dielectric and electromechanical properties and hence are commonly used for potential commercial applications. However, the effect of Nb2O5 with various polymorphs on structure and properties of the lead-based perovskite niobates has not been studied in literature. The aim of this study was to investigate the influence of Nb2O5 with various polymorphs on the processing–structure–property relationship in lead-based perovskite 0.5Pb(Yb1/2Nb1/2)O3-0.5PbTiO3 (PYNT) piezoceramics. The polymorphic state of Nb2O5 source dramatically affected densification, phase formation and microstructure evolution of the PYNT ceramics fabricated by applying closely controlled processing routes. Dense and pyrochlore-free PYNT ceramics with a minor amount of residual PbO were produced after sintering at 1100°C for 1 h with using 3 g atmosphere powder. Raman spectroscopy revealed that the PYNT ceramic produced using orthorhombic Nb2O5 had the most homogeneous cation ordering at the B-site as well as the least amount of the unknown phase caused by the Yb/Nb mixed compound, which resulted in up to 17% improvement in the piezoelectric and electromechanical properties with respect to the one produced using a mixture of orthorhombic and monoclinic Nb2O5. Therefore, care must be taken with initial powder characteristics, especially the crystalline structure of Nb2O5, for the sake of the fabrication of perovskite lead-based niobates with reproducible as well as enhanced properties.