Effect of Zr Doping on BNT–5BT Lead-Free Ceramics: Substitutional and Excess Incorporation Analysis

Abstract

This study evaluates the effect of zirconium (Zr) incorporation on the structural, microstructural, and functional properties of lead-free ceramics based on the 0.95(Bi0.5Na0.5)TiO3–0.05BaTiO3 (BNT–5BT) system. Two distinct doping strategies were investigated: (i) the substitutional incorporation of Zr4+ at the Ti4+ site (BNT–5BT–xZrsub), and (ii) the addition of ZrO2 in excess (BNT–5BT–xZrexc). The samples were synthesized via conventional solid-state reaction and characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM/EDS), and electrical measurements, including dielectric, ferroelectric, and piezoelectric responses. Both doping routes were found to influence phase stability and electromechanical performance. Substitutional doping notably reduced the coercive field while preserving high remanent polarization, resulting in an enhanced piezoelectric coefficient (d33). These results highlight the potential of Zr-modified BNT–5BT ceramics for lead-free energy harvesting applications.