Enhancement of Electromechanical Properties of Niobium Doped LeadFree Piezoelectric Ceramics

Abstract

BNT-ST ceramics are promising candidates for replacing lead-free (PZT) piezoelectric materials with the potential of outstanding dielectric and ferroelectric characteristics. In this work, 0.74(Bi0.5Na0.5TiO3)-0.26(SrTiO3) BNT-ST and Niobium substituted (Nb-BNT–26ST) ceramics were synthesized by solid-state reaction. The Niobium substitution was confirmed by XRD analysis and further analyzed by Raman spectra. SEM analysis and XRD and Raman helped understand the effect of Nb substitution on the grain growth and the structure within the selected composition range. Electromechanical properties of BNT–26ST ceramics initially increased with the addition of Nb peaking at Nb 0.5wt% and further decreased with increasing Nb content. Temperature-dependent dielectric spectrums showed that Td decreased below room temperature because of Nb substitution. The composition 0.5 wt% Nb yielded a maximum strain Smax of 0.28% ( ∗ ~ 600 ρm/V) at an electric field of 5 kV/mm at room temperature. Saturation polarization is maximized at 26 μC/cm2 at critical concentration of Nb 0.5%. The peaks became more diffuse, and the depolarization temperature decreased with the increasing Nb content. The work concluded that Nbdoped BNT-26ST is an excellent material for high-temperature, stable, lead-free piezoelectric devices.