Defect dipole induced large recoverable strain and high energy-storage density in lead-free Na0.5Bi0.5TiO3-based systems

Abstract

In this letter, we propose an effective route to obtain large recoverable strain, purely electrostrictive effects and high energy-storage density by inducing defect dipoles into Na0.5Bi0.5TiO3 (NBT)-based relaxor ferroelectrics. It has been found that pinched and double polarization hysteresis loops with high maximum polarization (Pmax) and negligible remanent polarization (Pr) can be observed due to the presence of acceptor-induced defect dipoles. A large recoverable strain of 0.24% with very little hysteresis and high electrostriction coefficient of 0.022 m4 C2 with purely electrostrictive characteristics were acquired when 11 mol. ‰ Mn-doped. Meanwhile, a high recoverable energy density of 1.06 J/cm3 with excellent temperature stability was obtained at the same composition owing to the enlarged value of Pmax-Pr (36.8 μC/cm2) and relatively high electric field (95 kV/cm). Our achievement can open up the exciting opportunities for ferroelectric materials in high-precision positioning devices and high electric power pulse energy storage applications.

Thermally stable large strain in low‐loss (Na0.2K0.8)NbO3‐BaZrO3 for multilayer actuators

“…Figure 7(A) shows a schematic diagram of the unit cell of the CNKN ceramic: the Cu 2+ ion in the center of the unit cell is indicated by the red circle, and an O 2− vacancy was formed at the (001) plane, as indicated by the dotted circle. 31,32 Finally, when P S had completely aligned with the direction of the applied electric field (Figure 7(B)), the polarization saturated in the CNKN ceramic. Therefore, a defect polarization (P D ) was formed between the Cu 2+ ion and oxygen vacancy in the unit cell of the CNKN ceramic along the [001] direction, as shown in Figure 7(A).…”

“…Normal P-E hysteresis curves were observed for the specimens with x ≥ 0.05, as The NKN ceramic exhibited a normal P-E loop with P r . 31,32 When a small electric field, which was too small to break the interaction between the P D and P S , was applied to the CNKN ceramic, the P s did not rotate, thereby resulting in no polarization, as indicated by I in Figure 6(A). Figure 7(A) shows a schematic diagram of the unit cell of the CNKN ceramic: the Cu 2+ ion in the center of the unit cell is indicated by the red circle, and an O 2− vacancy was formed at the (001) plane, as indicated by the dotted circle.…”

Electric-field-induced phase transition and pinched P–E hysteresis loops in Pb-free ferroelectrics with a tungsten bronze structure

“…A double P-E hysteresis loop can also be observed at temperatures slightly above the Curie temperature of the first-order ferroelectric transition, indicating the electric field-induced paraelectric-ferroelectric phase transition 15,16 . However, in the development of ferroelectric materials, a type of "pinched" P-E hysteresis loop with a constrained remanent polarization (P r ) value has been observed in various perovskite materials, e.g., Pb(Zr,Ti)O 3 solid solutions [17][18][19][20][21] , BiFeO 3 -based ceramics [22][23][24] , and (Bi 0.5 Na 0.5 )TiO 3 -based ceramics [25][26][27] . The main feature of the pinched P-E hysteresis loop is that the polarization, P r , for a zero electric field is small but finite, unlike ferroelectrics (large P r ) and antiferroelectrics (zero P r ) 9 .…”

“…The main feature of the pinched P-E hysteresis loop is that the polarization, P r , for a zero electric field is small but finite, unlike ferroelectrics (large P r ) and antiferroelectrics (zero P r ) 9 . Generally, the existence of pinched P-E hysteresis loops is attributed to strong domain wall pinning due to the diffusion of charged defects [17][18][19][20][21][22]25 . However, pinched P-E hysteresis loops can also be observed in defect-free ferroelectric materials, such as BiFeO 3 -based ceramics 23,24 and (Bi 0.5 Na 0.5 )TiO 3 -based ceramics 26 .…”

High energy storage density over a broad temperature range in sodium bismuth titanate-based lead-free ceramics

“…For further evaluating energy storage performance of the (1-x)LLBNTZ-xNBN ceramics, the comparison of W 1 and BDS between (1-x)BBNT-xNBN ceramics and other lead-free ceramics in recently reported results are shown in Fig. 9  1, 4, 10, 14, 16, 22, 23, 37, 40, 69–75 . It can be seen that the values of W 1 and BDS for (1-x)LLBNTZ-xNBN ceramics are higher than those of other lead-free ceramics.

Figure 8Calculated energy storage density, energy loss density and energy storage efficiency as a function of electric field for the (1-x)LLBNTZ-xNBN ceramics at room temperature.

Figure 9Comparison of W 1 and BDS between (1-x)LLBNTZ-xNBN ceramics and other lead-free ceramics.

…”