Field-induced strain and polarization response in lead-free Bi1/2(Na0.80K0.20)1/2TiO3–SrZrO3 ceramics

• BNKT–SZ ceramics were synthesized by a conventional solid state reaction process.
• Field-induced strain and piezoelectric constant were increased at critical composition.
• BNKT–SZ100x ceramics at x = 0.03 exhibit a large field induced dynamic piezoelectric coefficient.
• BNKT–SZ100x ceramics at x = 0.02 exhibit a high static piezoelectric constant.
• The depolarization temperature of BNKT–SZ100x ceramics decrease with increase in SZ content.

The structure, field-induced strain, polarization and dielectric response of lead-free SrZrO3-modified Bi1/2(Na0.80K0.20)1/2TiO3 (abbreviated as BNKT–SZ100x, with x = 0–0.05) ceramics were investigated. The X-ray diffraction analysis of BNKT–SZ100x ceramics reveals no remarkable change in the crystal structure within the studied composition range. Around critical composition (x = 0.03) at a driving field of 6 kV mm−1, large unipolar strain of 0.37% (Smax/Emax = 617) was obtained at room temperature. The ferroelectric and piezoelectric properties of BNKT ceramics were significantly increased at 2 mol%. At x = 0.02, remnant polarization reached a maximum value of 34 μC cm−2, while the piezoelectric constant (d33) attained maximum value of 190 pC/N. These results indicate that BNKT–SZ100x ceramics can be considered as promising candidate materials for lead-free piezoelectric actuator applications.