High strain response in ternary Bi0.5Na0.5TiO3–BaTiO3–Bi(Mn0.5Ti0.5)O3 solid solutions

Abstract

In this study, a ternary solid solution (0.935 − x)BNT–0.065BT–xBi(Mn_0.5Ti_0.5)O₃ (BNT–BT–BMnT; x = 0–0.030) was designed and fabricated by means of a conventional fabrication process. The composition and temperature dependencies of this material’s dielectric, ferroelectric and strain behavior were systematically investigated. XRD patterns of the BNT–BT–BMnT ceramics showed a single perovskite phase with pseudocubic symmetry for all investigated compositions. The substitution of BMnT into BNT–BT was found to induce a transition from the ferroelectric to the ergodic relaxor phase, resulting in significant disruption of the ferroelectric order along with a downward shift of the ferroelectric–relaxor transition temperature T_F–R to below room temperature. Accordingly, at a critical composition (2 mol% of BMnT), a high field-induced nonlinear strain of 0.45% was induced, with the normalized strain of 818 pm V⁻¹. Furthermore, the field-induced strain of the critical composition was stable at temperatures up to 100 °C owing to its stable nonpolar phase, suggesting that the developed material may be very attractive due to its temperature stability in the range of 30–100 °C. The high strain response in the critical composition was attributed to the reversible transformation between the ergodic relaxor and ferroelectric phases under the applied electric field.