Influence of BZT Doping on Structural and Multifunctional Properties of Lead Free BNT-ST Ceramics

Abstract The structural, microstructural, dielectric, ferroelectric, and electromechanical properties of (1-x) [0.97(Bi0.5Na0.5TiO3) − 0.03(SrTiO3)] − x[BaZr0.2Ti0.8O3] ceramics were systematically investigated to understand the effects of BaZr0.2Ti0.8O3 doping. X-ray diffraction and Rietveld refinement confirmed a pseudo-cubic structure at x = 0.03 and a tetragonal (P4bm)-cubic (Pm-3m) phase coexistence at x ≥ 0.05. Dielectric studies revealed a peak dielectric constant at x = 0.07 (~ 1000 at 1 kHz), correlating with structural instability. Ferroelectric measurements showed the highest remnant polarization (~ 27 µC/cm2) at x = 0.07, while increased doping (x ≥ 0.09) led to ergodic relaxor behavior (reduced Pr, Ec). Electromechanical response exhibited a strain enhancement from 0.12% (x =0.03) to 0.35% (x = 0.11), with normalized strain (d33*) increasing from 170 pm/V to 553 pm/V, attributed to enhanced electrostrictive effects. These findings establish x =0.07 as the critical composition for optimized dielectric and ferroelectric properties, while x≥ 0.09 demonstrates the potential for actuator applications.