Enhanced electric field induced strain in (1-x)((Bi_0.5Na_0.5)TiO₃-Ba(Ti, Zr)O₃)-xSrTiO₃ ceramics

In this paper, we investigated electric field induced strain (EFIS) and corresponding electric properties of the ternary ceramic system (1-x) (0.93(Bi_0.5Na_0.5)TiO₃ − 0.07Ba(Ti_0.945Zr_0.055)O₃)-xSrTiO₃ ((1-x)(BNT-BZT)-xST). The result of unipolar strain-electric field (S-E) measurement reveals a large EFIS of 0.4% at a driving electric field of 5 kV/mm is obtained in the component x = 0.2. The corresponding large signal d₃₃ ^* reaches up to 800 pm/V, which is superior to most reported BNT-based ceramics. This large EFIS only occurs in a narrow area where dominated nonergodic relaxor state (NR) just converts into ergodic relaxor state (ER). As ST content increases, the measurements of the electric properties suggest a deepening ergodic degree at room temperature (RT). The ferroelectric-to-relaxor transition temperature T_F-R can be modulated in a wide temperature range by the modification of ST. Since T_F-R reflects the coexisting limit of NR and ER, this effect is helpful to accomplish large EFIS at a certain temperature. Due to internal bias field existed in the samples, bipolar S-E loops exhibit asymmetry to form strain memory effect, which may offer another direction for memory device design. In view of such a low driving electric field required for the large EFIS production, (1-x)(BNT-BZT)-xST ceramics become a promising candidate for application in electromechanical devices.