Antiferroelectric‐ferroelectric phase transition in lead‐free AgNbO₃ ceramics for energy storage applications

Abstract

The high‐energy storage density reported in lead‐free AgNbO3 ceramics makes it a fascinating material for energy storage applications. The phase transition process of AgNbO3 ceramics plays an important role in its properties and dominates the temperature and electric field dependent behavior. In this work, the phase transition behavior of AgNbO3 ceramics was investigated by polarization hysteresis and dielectric tunability measurements. It is revealed that the ferrielectric (FIE) phase at room temperature possesses both ferroelectric (FE)‐like and antiferroelectric (AFE)‐like dielectric responses prior to the critical AFE‐FE transition point. A recoverable energy storage density of 2 J/cm3 was achieved at 150 kV/cm due to the AFE‐FE transition. Based on a modified Laudau phenomenological theory, the stabilities among the AFE, FE and FIE phases are discussed, laying a foundation for further optimization of the dielectric properties of AgNbO3.

Lead‐free Ag1−3xLaxNbO3 antiferroelectric ceramics with high‐energy storage density and efficiency

“…It should be noted that the energy storage efficiency η also increases from 0.42 (AN) to 0.63 (LAN2) and 0.87 (LAN5) due to the remarkably increased E F , E A and reduced E F ‐ E A with the incorporation of La 3+ . The results demonstrate the Ag 1−3 x La x NbO 3 ceramics exhibit more attractive comprehensive energy storage performance (with both high W rec and η ) than most of the reported AgNbO 3 ‐based and other lead‐free antiferroelectric ceramics (Figure B), making it promising a candidate for energy storage applications.…”

“…The energy storage properties of the as‐prepared LAN ceramics in this work and some other lead‐free antiferroelectric ceramics in literatures. A, W rec and η ; B, energy storage properties of AN and other lead‐free antiferroelectric ceramics, 0.828(Bi 0.5 Na 0.5 )TiO 3 –0.72BaTiO 3 –0.10NaNbO 3 (BNTBT–NN), 0.89(Bi 0.5 Na 0.5 )TiO 3 –0.06BaTiO 3 –0.05(K 0.5 Na 0.5 )NbO 3 (BNT–BT–KNN), AgNbO 3 (AN), Ag AgNbO 3 –0.2%MnO 2 (ANMn), Ag 0.97 Bi 0.01 NbO 3 (BAN), AgNbO 3 –0.1wt%WO 3 (AWN), Ag(Nb 0.85 Ta 0.15 )O 3 (ANT) [Color figure can be viewed at wileyonlinelibrary.com]…”

“…Silver niobate (AgNbO 3 ), which exhibits AFE‐like hysteresis loops at high electric field, being considered as a possible lead‐free alternative for lead‐containing AFE materials. It was reported to possess high recoverable energy density ( W rec ) of 1.6‐2.1 J/cm 3 , depending on the applied electric field, which is much higher than that of most lead‐free AFE ceramics. However, the ferroelectric M1 to antiferroelectric M2 phase transition appears at 60‐70°C (even though debates still remain about the detailed space group), leading to a weak FE behavior in this system at room temperature .…”

Progress, Outlook, and Challenges in Lead‐Free Energy‐Storage Ferroelectrics

“…[64] Besides this, phase transition from FE to AFE in AN ceramics have also been particularly investigated by revealing the existence of ferrielectric (FIE) phase. [65] Subsequently, Wei et al have confirmed the existence of submicron polar regions and twin boundary with numerous stacking faults in pure AN of orthorhombic lattice. The two kinds of ferroelectric domain in AN with critical temperature of 70 and 170 °C, respectively, have also significantly been observed, which can be identified as the primary reason for double P-E loop, finally reaching the ESD of 2.1 J cm −3 at 0.175 MV cm −1 and showing better performance, as shown in Figure 10d,e.…”

Ferroelectric, Photoelectric, and Photovoltaic Performance of Silver Niobate Ceramics

“…The frequency independent peaks at 353 °C correspond to the transition between antiferroelectric (AFE) phase Pbcm and paraelectric (PE) phase Cmcm . The relaxor‐like dielectric peaks and corresponding loss drop at around 75 °C are generally recognized as the phase change from polar Pmc2 1 to nonpolar Pbcm , indicating the coexistence of ferroelectric (FE) and AFE property at room temperature, which previously was also claimed as ferrielectric state of ANO . Besides, there is an indetectable dielectric anomaly around 180 °C (clearly collected in the cooling curves shown in Figure S1, Supporting Information), which is defined as freezing temperature ( T f ) in recent studies, suggesting the residual local polar regions in the temperature range from 75 to 180 °C.…”