Significantly enhanced energy storage performance of rare-earth-modified silver niobate lead-free antiferroelectric ceramics via local chemical pressure tailoring

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2019, Vol.7 (6), p.1551-1560
• Main Authors: Li, Song, Nie, Hengchang, Wang, Genshui, Xu, Chenhong, Liu, Ningtao, Zhou, Mingxing, Cao, Fei, Dong, Xianlin
• Format: Article
• Language: English
• Subjects: Antiferroelectricity; Ceramics; Dielectric breakdown; Dielectric strength; Diffraction patterns; Distortion; Electron diffraction; Energy; Energy storage; Ferroelectric materials; Ferroelectricity; Flux density; Freezing; Gadolinium; Gadolinium oxides; Lead free; Niobates; Organic chemistry; Raman spectroscopy; Rare earth elements; Switching; X-ray diffraction
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/C8TC05458D

Silver niobate (AgNbO 3 ) is considered as one of the most promising lead-free replacements for lead-containing antiferroelectric (AFE) ceramics, and has been drawing progressively more attention because of its relatively high energy storage density. However, weak ferroelectricity in pure AgNbO 3 exerts a negative impact on the energy storage performance, thus impeding the application of AgNbO 3 -based ceramics in high-power systems. In this study, an A-site doping strategy was employed to suppress the ferroelectric distortion and boost the AFE distortion of AgNbO 3 , based on local chemical pressure tailoring. An ultrahigh recoverable energy density ( W rec ) of 4.5 J cm −3 was achieved in Ag 0.88 Gd 0.04 NbO 3 ceramics, which is superior to that of other reported lead-free systems. The enhancement of energy storage performance is ascribed to two reasons: first, antiferroelectricity could be boosted by smaller ions and suitable vacancies on A-sites, evidenced by X-ray diffraction patterns, Raman spectroscopy, and selected-area electron diffraction measurements. Moreover, the decreasing freezing temperature ( T f ) and the increasing forward switching field ( E F ) as well as backward switching field ( E A ) with the increment of the gadolinium (Gd) content also confirmed the enhanced antiferroelectricity in Gd-doped AgNbO 3 ceramics. Second, the introduction of Gd 2 O 3 could effectively decrease the grain size and increase the dielectric breakdown strength (DBS = 290 kV cm −1 ). The performance due to local chemical pressure tailoring makes Gd-doped AgNbO 3 materials the most promising energy storage lead-free ceramics for dielectric energy storage capacitors.