Low-temperature dielectric anomalies in KSr2Nb5O15 ceramics with tetragonal tungsten bronze structure: The effect of microstructure

Liu, Liangliang; Wang, Yongqiang; Wang, Yan; Lv, Rui

doi:10.1016/j.jallcom.2019.152397

Cited by 13 publications

(4 citation statements)

References 34 publications

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“…Sr 2 KNb 5 O 15 (SKN) is a typical tetragonal tungsten bronze structure ferroelectric. The modest dielectric constant (≈1600) and low Curie temperature (≈160 °C) demonstrate its great potential for energy storage applications. , Nevertheless, the large grain size and high remanent polarization ( P r ) of the pristine SKN hinder its practical applications. In this study, a novel TB relaxor ceramic system Sr 2 KNb 5– x Ta x O 15 was synthesized for promising energy storage applications via the site engineering technology (see Figure ), in which Ta 5+ ions were introduced into the Nb 5+ site, wishing to break the long-range order polar structure by increasing the site disorder. , Furthermore, the introduction of Ta 5+ for Nb 5+ might also contribute to decreasing the grain size and improving the dielectric breakdown strength as the Ta 2 O 5 material exhibits strong refractory character and a large band gap .…”

Section: Introductionmentioning

confidence: 99%

“…The modest dielectric constant (≈1600) and low Curie temperature (≈160 °C) demonstrate its great potential for energy storage applications. 29,30 Nevertheless, the large grain size and high remanent polarization (P r ) of the pristine SKN hinder its practical applications. In this study, a novel TB relaxor ceramic system Sr 2 KNb 5−x Ta x O 15 was synthesized for promising energy storage applications via the site engineering technology (see Figure 1), in which Ta 5+ ions were introduced into the Nb 5+ site, wishing to break the long-range order polar structure by increasing the site disorder.…”

Section: ■ Introductionmentioning

confidence: 99%

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Pb/Bi-free Tungsten Bronze-Based Relaxor Ferroelectric Ceramics with Remarkable Energy Storage Performance

Wang

Zhang

et al. 2021

ACS Appl. Energy Mater.

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In this study, a Pb/Bi-free Sr2KNb5O15-based tungsten bronze relaxor ceramic system was developed for possible energy storage applications via the site engineering technology. The introduction of Ta at the Nb site enhanced the breakdown strength and relaxor nature of the Sr2KNb5O15 ceramic. An extremely high energy storage density (∼3.84 J/cm3) accompanied by a remarkable energy storage efficiency (∼93.2%) was obtained under an applied electric field of 410 kV/cm in the composition of Sr2KNb4.2Ta0.8O15. Meanwhile, the ceramic exhibited a relatively wide frequency stability (1–500 Hz) and thermal stability (30–120 °C) and displayed a remarkable fatigue endurance after 104 cycles. Even more surprisingly, the Sr2KNb4.2Ta0.8O15 ceramic processed excellent discharging performances with a short discharge time (τ0.9 < 75 ns), a large discharge current density (1019 A/cm2), and an amazing power density (125.6 MW/cm3). The impressive performances demonstrated that the Sr2KNb4.2Ta0.8O15 tungsten bronze ceramic might be a potential Pb/Bi-free dielectric material for high-power pulse capacitor applications.

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Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Pb/Bi-free Tungsten Bronze-Based Relaxor Ferroelectric Ceramics with Remarkable Energy Storage Performance

Wang

Zhang

et al. 2021

ACS Appl. Energy Mater.

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“…Figures 12(a), (b) reveal the dielectric constant behavior of microwave and conventionally sintered samples, respectively. Numerous factors affect the dielectric constant, such as the frequency, polarization, tetragonality ratio, and microstructure [51,52]. In the present study, the dielectric constant of the fabricated Ba 1−2x Ho 2x Ti 1−x Mn x O 3 (x = 0, 0.02, 0.04, and 0.06) piezoceramics has declined by increasing the frequency.…”

Section: Dielectric and Piezoelectric Propertiesmentioning

confidence: 54%

Ho-Mn co-doping in barium titanate piezoceramics via sol-gel process followed by microwave and conventional heating

et al. 2023

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Co-doped barium titanate (BT) piezoceramics are applied in advanced energy harvesting systems. In the present study, Ba1-2xHo2xTi1-xMnxO3 (x=0, 0.02, 0.04, and 0.06) were produced via the sol-gel-assisted solid state co-doping technique followed by microwave and conventional heating. In the current investigation, the synthesizing and phase characterization, allotropic transition, morphological examination, elemental analysis and dielectric-piezoelectric responses were investigated by X-Ray Diffraction (XRD), Differential Scanning Calorimetry (DSC) and Thermo-Gravimetric Analysis (TGA), Field-Emission Scanning Electron Microscope (FESEM), Energy-Dispersive x-ray Spectroscopy (EDS), Mapping analysis and inductance-Capacitance-Resistance meter (LCR meter) techniques, respectively. The XRD pattern and DSC/ TGA outcomes demonstrated that tetragonal BT phases without minor BaCO3 secondary phases are synthesized properly, and that the negligible unsolicited BaCO3 phases are thoroughly calcined by a microwave at 900℃. Doping resulted in an increase in tetragonality (c/a) of 0.19%, 0.15%, and 0.04%, respectively, compared to the pure calcined BT. Additionally, the crystallite size of BT decreased significantly by 59%, 58%, and 52%, respectively. The results revealed that the microwave-sintered samples have higher purity, drastic delicate and finer grain size distribution, and superior tetragonal-ity with respect to the conventionally sintered furnace samples. Furthermore, the piezoelectric constant for the microwave sintered and the conventionally sintered samples with the same value of x=0.04 were 390 and 370 (pC/N), respectively, which established that the sintering method has satisfactory affection (approximately 6%) on the piezo function of the samples. Eventually, the prepared samples which had 0, 2, 4, and 6 % moles of Ho3+-Mn2+ cations and were sintered by a microwave compared to the similar specimens fabricated by the furnace had superior dielectric constants of 2.6, 1.1, 2.2 and 2.9 times, respectively.

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“…Where structural distortions in TTBs are small they impart only subtle modi cations to diffraction patterns that are easily mismodelled, or even overlooked. Moreover, microstructure and crystallite size has been shown to have an impact on the properties of these materials, 14 arguably requiring structure and property to be thoroughly assessed concurrently on the same samples if reliable trends are to be drawn.…”

Section: Introductionmentioning

confidence: 99%

Structural origins of dielectric anomalies in the filled tetragonal tungsten bronze, Sr2NaNb5O15

Tidey,

Dey,

Sanchez

et al. 2024

Preprint

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The tetragonal tungsten bronze, Sr2NaNb5O15, shows promise for application in high-temperature high-efficiency capacitors vital for the sustainable energy revolution. Previously, the structural complexity of this and related materials has obscured the mechanisms underpinning two large anomalies in relative permittivity (εr) which give rise to their exceptionally broad dielectric response. We comprehensively investigate the structural evolution from − 173 to 627°C, combining electron, X-ray and neutron diffraction, electron microscopy, and first principles electronic structure calculations to unambiguously identify the structural origins of both anomalies. The peak in εr at 305°C is associated with a polar-nonpolar phase transition, wherein cations displace along the c-axis. Guided by DFT, we identify a further transition upon cooling, associated with the second peak at − 14°C, linked to the softening of an in-plane polar distortion with a correlation length limited by ferroelastic nano-domains arising from rigid-unit-like tilting of NbO6 octahedra at high temperature, imparting relaxor-like behaviour. Thus, the two dielectric anomalies in Sr2NaNb5O15 are associated with two distinct crystallographic phase transitions and their interplay with a microstructure that arises from a third, non-polar structural distortion. Chemical control of these will enable development of tuneable materials with dielectric properties suitable for high-temperature energy storage applications.

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Low-temperature dielectric anomalies in KSr2Nb5O15 ceramics with tetragonal tungsten bronze structure: The effect of microstructure

Cited by 13 publications

References 34 publications

Pb/Bi-free Tungsten Bronze-Based Relaxor Ferroelectric Ceramics with Remarkable Energy Storage Performance

Pb/Bi-free Tungsten Bronze-Based Relaxor Ferroelectric Ceramics with Remarkable Energy Storage Performance

Ho-Mn co-doping in barium titanate piezoceramics via sol-gel process followed by microwave and conventional heating

Structural origins of dielectric anomalies in the filled tetragonal tungsten bronze, Sr2NaNb5O15

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