0.4% Electrostrain at Low Field in Lead-Free Bi-Based Relaxor Piezoceramics by La Doping

Abstract

This work investigates the effects of lanthanum doping on the crystal structure, surface morphology, dielectric properties, ferroelectric properties, piezoelectric properties, and electromechanical strain properties of lead-free (Bi0.47Na0.47Ba0.06)1−xLaxTiO3 piezoelectric ceramics. All specimens were fabricated by a traditional solid-state reaction method. The results of crystal structure and dielectric properties categorize all specimens as relaxor materials. The results of dielectric properties and ferroelectric properties confirm the nonergodic-to-ergodic transformation as a function of La content. At the phase transition point, the material shows a high electric field-induced strain of 0.4% under an applied electric field of 5 kV/mm. The large electromechanical strain response at low applied field in the 0.02 mol La specimen may contribute to the two synergistic effects. First, the electric field induced the reversible ergodic-ferroelectric phase transition, which can generate the large strain. Second, the nonergodic and ergodic phases coexist at the phase transformation point, which can reduce the driving field by facilitating the growth of ferroelectric domains.