Ferroelectric, piezoelectric properties and thermal expansion of new Bi(Ni3/4W1/4)O3–PbTiO3 solid solutions

Abstract

Ceramics of the Bi(Ni_3/4W_1/4)O₃–PbTiO₃ (BNW–PT) ferroelectric system were synthesized using a conventional solid-state sintering process. A morphotropic phase boundary (MPB) region separating tetragonal and rhombohedral phases has been determined based on X-ray diffraction (XRD) analysis. The composition-dependent phase transition behavior, thermal expansion, di/ferro/piezoelectric properties have been systemically investigated. The volume TECs (thermal expansion coefficients) for 0.1BNW–0.9PT and 0.2BNW–0.8PT are −1.01 × 10⁻⁵ per °C and −0.94 × 10⁻⁵ per °C, respectively, indicating the negative thermal expansion of some compositions for the binary system. The BNW–PT ceramics have Curie temperatures, T_C, ranging from 460 °C to ∼152 °C with the variation of BNW constituent. The tetragonal-rich composition 0.20BNW–0.80PT is found to have the largest remnant polarization, P_r ∼ 23.4 μC cm⁻². The highest piezoelectric coefficient d₃₃ ∼ 145 pC N⁻¹ is achieved at MPB composition 0.32BNW–0.68PT. The maximum strain value ∼0.194% is also obtained in the 0.32BNW–0.68PT ceramic.