Simultaneously enhancing the T_d and the thermal stability of the real‐time d₃₃ in BNT‐based piezoceramics

Abstract

One of the inherent disadvantages of Bi 0.5 Na 0.5 TiO 3 -based (BNT-based) piezoceramics is that an increment of the depolarization temperature (T d ) is generally accompanied by a deterioration of the temperature stability of the real-time piezoelectric constant (d 33 ), which severely restricts the practical applications of the materials. Herein, we propose a new strategy to mitigate the conflict between the elevation of T d and the temperature stability of the real-time d 33 in BNTbased ceramics via integrating the pressure-assisted sintering and quenching process. By this strategy, we not only increased the T d from 109 to 166 • C but also improved the temperature stability of the real-time d 33 (the temperature coefficient T tc = ± 13 pC/N) in 0.94Bi 0.5 Na 0.5 TiO 3 -0.06BaTiO 3 ceramic. Both the built-in field and the increment of the field-induced R3c phase fraction play the significant role in enhancing the T d and the temperature stability of the realtime d 33 . Thus, our work provides a simple and effective approach for designing piezoceramics with high T d and a superior temperature stability of the real-time d 33 .

Realizing an Ultrahigh Depolarization Temperature near the Curie Point and Large d33 with Superior Temperature Stability in Lead-Free Ceramics via a Sandwich Structure Design

“…These samples were poled via applying a direct current (DC) bias field of 40 kV/cm for 10 min. 34 indicating that the pinching effect caused by the oxygen vacancy 20 is conducive to stabilize the field-induced ferroelectric state, as shown in Figure 3a and Figure S1a of the Supporting Information. This result can also be confirmed in Figure 3b and Figure S1b of the Supporting Information, yet the deferment of the FEs−REs phase transition is at the cost of piezoelectric response because the enhancement of oxygen vacancy also hinders the switching of the ferroelectric domain upon poling.…”

Boosting dielectric temperature stability in BNBST‐based energy storage ceramics by Nb2O5 modification

“…Of which sodium bismuth titanate (Bi 0.5 Na 0.5 TiO 3 , BNT) is a typical lead-free ferroelectric ceramic with high Curie temperature (T c ∼ 320 • C), large saturated polarization (P s > 40 μC/cm 2 ) and diffusive phase transition behavior for temperature-dependent dielectric constant (ε r -T) curve, and regarded as one of the most promising and competitive environment-friendly ferroelectric ceramics. [21][22][23][24][25][26] However, the large remnant polarization (P r ∼ 38 μC/cm 2 ) and high coercive field (E c ∼ 70 kV/cm) make the P-E hysteresis loop of BNT ceramic showing a fat shape, which needs to be slim and then suitable for energy storage applications. 27,28 Meanwhile, the ε r of BNT ceramics in the low-temperature region is very low, which leads to poor dielectric temperature stability, and greatly restricts its application in the wide temperature region.…”

“…Accordingly, the focus of research of energy storage ceramics has shifted to lead‐free relaxor and antiferroelectric systems. Of which sodium bismuth titanate (Bi 0.5 Na 0.5 TiO 3 , BNT) is a typical lead‐free ferroelectric ceramic with high Curie temperature ( T c ∼ 320°C), large saturated polarization ( P s > 40 μC/cm 2 ) and diffusive phase transition behavior for temperature‐dependent dielectric constant ( ε r – T ) curve, and regarded as one of the most promising and competitive environment‐friendly ferroelectric ceramics 21–26 . However, the large remnant polarization ( P r ∼ 38 μC/cm 2 ) and high coercive field ( E c ∼ 70 kV/cm) make the P – E hysteresis loop of BNT ceramic showing a fat shape, which needs to be slim and then suitable for energy storage applications 27,28 .…”