Ferroelectric, dielectric properties and large strain response in Zr-modified (Bi0.5Na0.5)TiO3–BaTiO3 lead-free ceramics

In the present work, temperature and composition dependence of dielectric, ferroelectric, piezoelectric properties of the (Bi0.5Na0.5)0.93Ba0.07Ti1−xZrxO3 lead-free ceramics were systematically investigated and a schematic phase diagram was proposed. It was found that the Zr substitution caused the crystal lattice distortion, leading to a structural evolution from the ferroelectric long-range-order to relaxor pseudocubic structures characterized by the decreased depolarization temperature, ferroelectric remnant polarization, quasi-static piezoelectric coefficient, and electromechanical response. Results indicated that at a critical composition x of 0.014, large strain response could be obtained with the normalized strain Smax/Emax as high as 573 pm/V under a moderate field of ~4 kV/mm at room temperature. The large strain response with enhanced temperature stability would be quite suitable for environmental-friendly solid-state actuators.