Electric field-induced strain response of lead-free Fe 2 O 3 nanoparticles-modified Bi 0.5 (Na 0.80 K 0.20 ) 0.5 TiO 3 -0.03(Ba 0.70 Sr 0.03 )TiO 3 piezoelectric ceramics

Abstract

Abstract In this research, the effects of Fe 2 O 3 nanoparticles additive on the phase evolution, dielectric, ferroelectric, piezoelectric and electric field-induced strain responses of BNKT-based piezoelectric ceramics were systematically investigated. The Bi 0.5 (Na 0.80 K 0.20 ) 0.5 TiO 3 -0.03(Ba 0.70 Sr 0.03 )TiO 3 or BNKT-0.03BSrT piezoelectric ceramics with the addition of 0–2 vol% Fe 2 O 3 nanoparticles were prepared by a solid-state reaction method. Optimum sintering temperature was found to be 1125 °C for 2 h at which all compositions had high densities of 5.73–5.80 g/cm 3 . All compositions exhibited a perovskite structure with no impurity. The XRD result showed coexisting rhombohedral and tetragonal phases throughout the entire compositional range with the rhombohedral phase becoming dominant at higher Fe 2 O 3 content. The addition of Fe 2 O 3 promoted the diffuse phase transition in the system that is characteristic of a relaxor-like mechanism and interrupted the polarization which leads to a reduction in the remanent polarization and coercive field. However, the destabilization of the ferroelectric order is accompanied by a significant increase in electric field-induced strain response for the studied system. A large electric field-induced strains ( S max ) of 0.38% and a normalized strain coefficient ( d * 33 = S max / E max ) of 760 pm/V were obtained for the 1 vol% Fe 2 O 3 ceramic. The obtained results indicate that the addition of Fe 2 O 3 significantly enhances the field-induced strain in BNKT-0.03BST ceramics, and the studied material is considered as a promising candidate for lead-free electromechanical actuator applications.