Search

• A high W r of 4.97 J/cm3 and an η of 84.4% are obtained in BNT-based ceramics. • The W r of 2.73 J/cm3 with η of 80.6% are obtained at 140 ℃. • A superior temperature performance compared with other typical dielectric materials. • A strategy of precisely adjusting the relaxation and ferroelectricity states. Dielectric energy storage materials have attracted much attention because of their wide applications in the electronics industry. However, low energy storage density and poor thermostability limit their application. In this work, a strategy was proposed to prepare lead-free relaxor ferroelectric ceramics with ultra-high energy storage properties and superior temperature stability by precisely adjusting the relaxation and ferroelectricity states and increasing the electric field intensity. An ultra-high recoverable energy storage density (W r) of 4.97 J/cm3 and an efficiency (η) of 84.4% are simultaneously obtained for the 0.95(0.9Bi 0.5 Na 0.5 TiO 3 -0.1Ba 0.85 Ca 0.15 Zr 0.1 Ti 0.9 O 3)-0.05BaSnO 3 ceramic. Moreover, a high W r of 2.73 J/cm3 with brilliant η of 80.6% are obtained in the ceramic at 140 ℃ and there is almost no thermal degradation of energy storage properties from 25 ℃ to 140 ℃. The W r and η have decreased by 2.2% and 1.9% after 105 cycles under 200 kV/cm, respectively, which demonstrates the good cycle stability of the sample. A discharge power density of up to 99.0 MW/cm3 is obtained in the 0.95(0.9Bi 0.5 Na 0.5 TiO 3 -0.1Ba 0.85 Ca 0.15 Zr 0.1 Ti 0.9 O 3)-0.05BaSnO 3 ceramic and the good charge and discharge performance of this sample is important for practical applications. [ABSTRACT FROM AUTHOR]

• A comprehensive strategy of hybridizations of Bi3+ orbitals and relaxor was adopted. • Relaxor behavior was analyzed via Raman spectroscopy and the Curie-Weiss law. • BNT-0.40ST-0.02FN composition exhibits high W (3.36 J/cm3) and η (81%) under a low electric field of 170 kV/cm. • BNT-0.40ST-0.02FN ceramic shows superior thermal stability (25–200 °C). • The BNT-0.40ST-0.02FN ceramic possesses potential to be employed in pulsed power devices under extreme conditions. Dielectric ceramics are highly favorable for pulsed power applications owing to their ultra-fast charge-discharge speed and excellent reliability. However, their low energy density under low electric fields remains as a bottleneck for them to be employed in integrated electronic devices with shrinking dimensions. In this work, we have designed a comprehensive strategy to synthesize lead-free (Bi 1/2 Na 1/2) 1−x Sr x Ti 0.98 (Fe 1/2 Nb 1/2) 0.02 O 3 (BNT-xST-2FN, x = 0.30, 0.35, 0.40 and 0.45) ceramics via traditional solid-state method. On one hand, the hybridizations of Bi3+ orbitals and the displacement of B-site cations under the applied electric field lead to a high polarization. On the other hand, the (Fe 1/2 Nb 1/2)4+ complex-ion and SrTiO 3 were introduced to improve the relaxor behavior of the system, resulting in a high energy-storage efficiency. In this way, an excellent energy density of 3.36 J/cm3 and a high energy efficiency of 81% are simultaneously achieved in the BNT-0.40ST-0.02FN composition under a low electric field of 170 kV/cm, which is superior to other BNT-based materials under similar electric fields. Moreover, the ceramic exhibits a superior thermal stability (25–200 °C). This work provides a promising approach for designing high-performance lead-free energy storage ceramics under low electric fields. [ABSTRACT FROM AUTHOR]

• Grain tuning and relaxor construction strategy was adopted in this work. • The W rec of 5.5 J/cm3 and W t of 6.4 J/cm3 were achieved in 0.6BNT-0.4SBTH ceramic. • The ceramic displayed good thermal stability and frequency insensitivity. Relaxor ferroelectrics have become competitive candidates in energy storage applications owing to their relatively high maximum polarization, high breakdown strength, and relatively low remnant polarization. Here, Bi 0.5 Na 0.5 TiO 3 (BNT) with large polarization was selected as the base composition, and Sr 0.7 Bi 0.2 Ti 0.8 Hf 0.2 O 3 (SBTH), as a dopant, was added into BNT to improve its relaxor behavior and decrease the grain size. A series of (1- x)Bi 0.5 Na 0.5 TiO 3 - x Sr 0.7 Bi 0.2 Ti 0.8 Hf 0.2 O 3 (abbreviated as (1- x)BNT- x SBTH, x = 0.1, 0.2, 0.3 and 0.4) ceramics were synthesized. The addition of SBTH resulted in the increase in structural disorder, as confirmed by the red-shift in Raman spectra, the enhancement of the relaxor characteristic and the fast response of the domains in local poling measurements. As a result, excellent energy storage properties (with the recoverable energy storage density of 5.5 J/cm3 and efficiency of 85.9 % at 410 kV/cm) were realized in the 0.6BNT-0.4SBTH sample. Moreover, the sample also exhibited excellent thermal stability (20 °C to 200 °C) and frequency insensitivity (0.5–500 Hz). These results suggest that BNT-based relaxor ferroelectric ceramics modulated by SBTH possess great potential in dielectric energy-storage capacitors. [ABSTRACT FROM AUTHOR]

[Display omitted] • Utilize an average ionic polarizability design strategy to balance W rec and η. • The high-polarization gene is maintained and the polar order is disrupted. • Achieve excellent energy-storage properties both in low-field and moderate-field. • The existence of dynamic PNRs is confirmed by PFM measurements. • The temperature-dependent Raman spectra reveal the variation of local structure. Electrostatic capacitors are promising candidates in the application of pulse-power systems due to their high power density and fast charge-discharge rate. However, the insufficient recoverable energy density (W rec) and energy efficiency (η) under low/moderate electric field is still the bottleneck for their applications in miniaturized equipment and portable devices. In this work, we utilize an average ionic polarizability design strategy to enhance W rec by sustaining the high-polarization gene of the system and simultaneously improve η by disrupting the polar order in (1- x)[0.7Bi 0.5 Na 0.5 TiO 3 -0.3Sr 0.7 Bi 0.2 TiO 3 ]- x Sr(Zn 1/3 (Nb 0.85 Ta 0.15) 2/3)O 3 ceramics. As a result, excellent energy-storage properties have been achieved both in low-field (W rec ∼ 2.7 J/cm3 and high η ∼ 93% at 200 kV/cm) and moderate-field (W rec ∼ 5.2 J/cm3 and η ∼ 91% at 330 kV/cm) for x = 0.12 sample. Additionally, the x = 0.12 sample exhibits good thermal stability (−50 ∼ 200 ℃), frequency stability (0.5 ∼ 500 Hz) and cycle stability (105 cycles). Hence, the current work may provide some novel perspectives for improving the W rec and η of dielectric capacitors under low/moderate electric fields. [ABSTRACT FROM AUTHOR]

[Display omitted] • Moderate Bi3+ content is helpful to enhance activation energy and breakdown field. • Through introducing A-site defect, the slim loop and high Δ P are received in SBT2. • Ultrahigh W rec of 4.77 J/cm3 and η of 85.7% were obtained in Sr 0.7 Bi 0.2 TiO 3 ceramic. • Sr 0.7 Bi 0.2 TiO 3 ceramic shows good temperature stability at 20–160 °C. • An outstanding fatigue resistance after 105 cycles was achieved in Sr 0.7 Bi 0.2 TiO 3. The application of dielectric capacitors with high energy density is very important to solve the increasingly serious energy crisis. However, the further improvement of energy density is seriously confining by their poor breakdown fields. In this work, outstanding energy storage performance is achieved in Sr 0.7 Bi x TiO 3 (x = 0.1, 0.2, 0.3 and 0.4) ceramics via A-site defect and grain size tuning. It was found that the moderate Bi3+ content is helpful to reduce sintering temperature and refine grain size, which lead to higher activation energy and breakdown field. Besides, moderate Bi3+ doping in A-site enhances polarity owing to the hybridizations between 6p orbital of Bi and 2p orbital of O. Thus, a high recoverable energy density of 4.77 J/cm3 with prominent efficiency of 85.7% at 570 kV/cm is realized in Sr 0.7 Bi 0.2 TiO 3 ceramic. Moreover, the Sr 0.7 Bi 0.2 TiO 3 ceramic also displays superior thermal stability from 20 °C to 160 °C and excellent fatigue endurance over 105 cycles. Our results in this work offer a better understanding and design methodology for developing novel high-performance dielectric capacitors. [ABSTRACT FROM AUTHOR]