Enrichment of piezoelectric properties in Nb5+doped (0.94) (Na0.5Bi0.5)TiO3–(0.06) BaTiO3 ceramics across morphotropic phase boundary region

Lead-free piezoelectric compounds (0.94)(Na0.5Bi0.5)TiO3–(0.06) BaTiO3 [NBBT (94/06)] + x wt.% Nb5+ (x = 0%, 1%, 1.5%, 2%, and 2.5%) were synthesized by the solid-state reaction route and these powders were pelletized and sintered for dielectric and piezoelectric characterization. The phase coexistence Monoclinic (Cc) + Rhombohedral (R3c) was affirmed using X-ray Powder diffraction analysis. The structural properties like cell parameters and space group of the synthesized ceramics were investigated by the Rietveld refinement analysis. The surface morphology and grain size of the fractured ceramics were explored using SEM imaging technique. The dielectric properties for all the ratios of NBBT (94/06) ceramics were examined using LCR meter. The piezoelectric coefficients such as d33 and g33 of Nb-doped NBBT (94/06) ceramics were investigated. The saturation polarization (Ps) and remanent polarization (Pr) were exhibited from the P–E hysteresis loop analysis at room temperature. The appropriate addition of Nb5+ (x = 1.5%) in NBBT (94/06) material demonstrates eminent dielectric constant and piezoelectric coefficient d33 than other wt.% of Nb. The replacement of Ti4+ with higher radius cations Nb5+ in B-site of ABO3 composes tilting of polar BO6 octahedra resulting in rhombohedra distortion (RD) (90° − α), in addition, the polarizability of ions and various valance states of B-site cations could be responsible for RD (90° − α) ensuing relatively high dielectric constant and piezoelectricity.