Large electrostrictive properties via double defect dipole designing in Na0.5Bi0.5TiO3 -based ceramics

Electrostriction is key in high-precision electronic actuators because of its low hysteresis. In this study, using the variable valence of Ti atoms at the B-position in ceramics, W⁶⁺is induced in Na_0.5Bi_0.5TiO₃-based ceramics to realize an electrovalence difference among local ions in the lattice. To maintain the electrovalence balance, the “Ti³⁺-W⁶⁺-Ti³⁺” double-dipole structure is formed, which can be demonstrated via density functional theory calculations. The stress field from the dipole structure denotes the pinning effect and constrains the B-site ions, thus resulting in a large electrostrictive coefficient. Moreover, the built-in electric field from the dipole structure provides the driving force for domain flipping as well as reduce hysteresis. Additionally, the dipole structure offers a large Q₃₃of 0.0475 m⁴/C²when the W⁶⁺content is 2.5 %.