NBT-based Ceramics Research Articles

Phase evolution, dielectric thermal stability, and energy storage performance of NBT-based ceramics via viscous polymer process

There is an urgent need to develop stable and high-energy storage dielectric ceramics; therefore, in this study, the energy storage performance of Na0.5-xBi0.46-xSr2xLa0.04(Ti0.96Nb0.04)O3.02 (x = 0.025–0.150) ceramics prepared via the viscous polymer process was investigated for energy storage. It was found that with increasing Sr2+ content, the material transforms from a mixture of rhombohedral and tetragonal phases (x = 0.025) to a mixture of orthorhombic and pseudo-cubic phases (x = 0.15). The emergence of a dielectric plateau for the sample with x = 0.15 widens the applicability of the host compound. Finite element simulations show that a smaller grain size has a beneficial effect on the critical breakdown electric field and that the relaxor transformation benefits from the reduction of residual polarization (Pr). The obtained ceramics achieve a value of 6.69 J/cm3 for the energy storage density (Wrec) and 89.48 % for the energy storage efficiency (η) under an applied electric field of 400 kV/cm, with a discharge time (t0.9) of 0.168 μs at 90 % of the energy under an electric field of 280 kV/cm, and a power density (Pd) of 148 MW/cm3. This study shows a novel strategy for the modification of the dielectric and ferroelectric properties of NBT-based ceramics, providing an effective way to expand the operational temperature range and improve energy storage performance.

Effects of CaTiO3 size on the electrical properties of NBT-based ceramics

Relaxor ferroelectrics are the most promising materials for dielectric capacitors because of their rapid charge/discharge capability and outstanding thermal stability. However, to satisfy the advanced requirements of pulsed power capacitors, these electrical properties need substantial enhancement. In this paper, the breakdown strength of the ceramic is improved by constructing a barrier layer with CaTiO3 filler in the system, and it optimizes the ceramic's electrical characteristics by regulating the size of the filler. Subsequently, the relaxor behavior is enhanced, achieving a dispersion coefficient of 1.75, and the band gap (Eg) increases to 2.67 eV, raising the breakdown strength from 140 kV/cm to 220 kV/cm, maintaining relatively good temperature stability. The recoverable energy storage density (Wrec) achieved is 0.73 J/cm3 using CaTiO3 with dimensions of 5.80×2.10×2.20 μm. This paper proposes a novel strategy to boost the electrical performance of dielectric materials.

Cu2+ and W6+ co-doped Na0·5Bi0·5TiO3 solid solution: An effective approach to inhibit oxygen vacancy generation and suppress oxygen ion conduction

Thanks to its outstanding features, the Na0·5Bi0·5TiO3 is a promising as a dielectric material for various advanced electronic devices. However, its high oxygen ionic conductivity and wide band-gap energy pose limitations on its suitability for commercial applications. In this work, an approach to inhibit oxygen vacancy generation and suppress oxygen ion conduction is investigated through the B-site donor and acceptor doping strategy. This study aims to investigate the morphological, structural, compositional, dielectric, electric, and optical properties of 0.99NBT-0.01BCW and 0.985NBT-0.015BCW perovskite ceramics. The research also explores the impact of Cu2+ and W6+ substitution on the perovskite structure and its potential applications. Morphological analysis revealed well-defined grains with cubic shapes, influenced by Cu2+ and W6+ incorporation. Structural analysis confirmed a rhombohedral lattice with R3c space group. Dielectric analysis showed ferroelectric to antiferroelectric and antiferroelectric to paraelectric phase transitions, with emphasis on relaxor behavior influenced by BCW doping. Electric analysis demonstrated a semiconductor behavior with activation energies, suggesting inhibited conduction loss at high temperatures due to BCW doping. Optical analysis revealed direct bandgap energies suitable for applications in optoelectronics and photonics. These findings suggest that doping with Cu2+ and W6+ restrains conduction losses at elevated temperatures, potentially serving as the primary mechanism for suppressing the high-temperature dielectric loss in NBT-based ceramics. They highlight the potential of these perovskite ceramics in applications such as capacitors, sensors, and optoelectronic devices.

Modulation of photoluminescence properties by poling and quenching strategy in rare earth ions doped Na1/2Bi1/2TiO3-based ceramics

With the continuous development of the society, optical ceramics are more and more widely used in daily life. In this work, the photochromic (PC) and photoluminescence (PL) properties of Na1/2Bi1/2TiO3 (NBT)-based ceramics doped with different rare-earth elements (Er, Eu, and Ho) are investigated. It is found that NBT-Er\\Eu and NBT-Er\\Ho ceramics have good up-conversion PL properties under 980 nm laser excitation. After poling and quenching treatments, the PL intensity of NBT-Er\\Eu ceramics increases by 1.5 and 11.7 times, respectively, and the NBT-Er\\Ho ceramics increases by 5.1 and 3.6 times, respectively. Besides, the rare-earth ions doped NBT-based ceramics exhibit fast PC response and self-bleaching behavior. In addition, multicolor luminescence behavior (from bright green to orange-yellow) is obtained in NBT-Er\\Eu ceramics, suggesting the potential application of this material in the field of optical information storage and optical anti-counterfeiting. Therefore, this work not only provides a new PC material exhibiting fast PC response and self-bleaching behavior, but also develops new universal strategies to modulate PL properties without changing the composition.

Enhanced energy storage performance of Na0.5Bi0.5TiO3-based relaxor ferroelectric ceramics by synergistic optimization strategies

Despite the fact that Na0.5Bi0.5TiO3 (NBT) based lead-free ceramics have attracted widespread interest due to their various advantages, their lower recoverable energy storage density (Wrec) and energy storage efficiency (η) limit their development in pulsed power capacitors. In this work, we propose a synergistic optimization strategy to enhance the energy storage performance of 0.65Na0.5Bi0.5TiO3-0.35SrTiO3(NBST) based lead-free ceramics by introducing Bi0.8La0.2(Ni0.5Zr0.5)O3 (BLNZ) and employing viscous polymer process (VPP). The former converts the macroscopic domains into microscopic domains, limiting the polarization response hysteresis to give a large Pm–Pr. The latter reduces the thickness and porosity of the samples, resulting in a substantial increase in breakdown strength. Ultimately, by stepwise optimization of this strategy, the x = 0.15 ceramic by VPP (0.15VPP) achieves excellent energy storage performance (Wrec = 7.6 J/cm3, η = 92%) under 620 kV/cm and reliable temperature stability from 20-140 °C. The combined excellent results of this study show that our synergistic optimization strategy can effectively enhance the energy storage performance of NBT-based dielectric ceramics and could be further extended to other ceramic materials for pulsed power capacitors.

Composition and electric field driven studies on modified NBT-based lead-free ceramics

A considerable increase in the c/a ratio, tilt angle, octahedral strain, and Ti-Ti distance with an application of electric field was observed for all the compositions in (1-x) (Na0.5Bi0.5TiO3).x(Ba0.85Ca0.15Ti0.90Zr0.10O3) ceramics. In the x = 0.09 sample, a P4bm phase (∼45 %) was observed which reduced to ∼ 15 % upon poling. The tilt angle modifies the A1 phonon mode at 784 cm−1 upon substitution and application of the electric field. Incorporating Ba0.85Ca0.15Ti0.90Zr0.10O3 increased the maximum dielectric permittivity (εm) from ∼ 2466 (x = 0) to ∼ 3231 (x = 0.09). The degree of diffuseness (γ) also increased with substitution from ∼ 1.384 (x = 0) to ∼ 1.980 (x = 0.09). With poling the value of γ was observed to decrease for each composition. The transformation from a compressive octahedral strain to a tensile one increased the piezoelectric coefficient (d33). The d33 value increased from ∼ 70 (x = 0) to ∼ 120 (x = 0.06).

Energy Storage and Charge/Discharge Performance of Sm-Doped NBT-Based Lead-Free Ceramics

Energy Storage and Charge/Discharge Performance of Sm-Doped NBT-Based Lead-Free Ceramics

Excellent Piezoelectric Properties of NBT-Based Lead-Free Ceramics Through Regulation of Oxygen Vacancies

Excellent Piezoelectric Properties of NBT-Based Lead-Free Ceramics Through Regulation of Oxygen Vacancies

Electric field-temperature phase diagram and electrical properties of (1-x)Na0.5Bi0.5TiO3 - xK0.5Bi0.5TiO3 ceramics

Electrically and thermally induced transitions between ferroelectric and relaxor states are of great significance in Na1/2Bi1/2TiO3 (NBT)-based materials due to their remarkable similarity to electromechanical properties. However, an in-depth understanding of the family of this material remains challenging, primarily due to its structural complexity and diverse behaviour with or without the presence of an external electric field. For enhancing NBT-based ceramics and enabling the analysis of their electric field temperature (E-T) phase diagrams, it has been suggested that K0.5Bi0.5TiO3 (KBT) could be used as a dopant material. This study thoroughly examines the electrical, microstructural, and ferroelectric (FE) properties of (1-x)NBT-xKBT ceramics. The incorporation of KBT into NBT, inducing a change in structural symmetry, reveals the coexistence of rhombohedral and tetragonal phases (x ∼ 0.2), as confirmed by X-ray diffraction. Using a modified KWW function, electrical modulus (EM) analysis illustrates a non-Debye-type relaxation process. Moreover, it is observed that temperature influences the transition of the material among its ferroelectric (FE), ergodic (ER), and non-ergodic (NR) relaxor phases. This report proposes that the E-T phase diagram can serve as a valuable tool for determining optimal conditions and selecting materials for electromechanical and actuator-based applications.

Outstanding Energy Storage Performance of NBT-Based Ceramics under Moderate Electric Field Achieved via Antiferroelectric Engineering.

Ultrahigh energy-storage performance of dielectric ceramic capacitors is generally achieved under high electric fields (HEFs). However, the HEFs strongly limit the miniaturization, integration, and lifetime of the dielectric energy-storage capacitors. Thus, it is necessary to develop new energy-storage materials with excellent energy-storage densities under moderate electric fields (MEFs). Herein, the antiferroelectric material Ag0.9Ca0.05NbO3 (ACN) was used to modify the relaxor ferroelectric material 0.6Na0.5Bi0.5TiO3-0.4Sr0.7Bi0.2TiO3 (NBT-SBT). The introduction of ACN results in high polarization strength, regulated composition of rhombohedral (R3c) and tetragonal (P4bm), nanodomains, and refined grain size. An outstanding recoverable energy density (Wrec = 4.6 J/cm3) and high efficiency (η = 82%) were realized under an MEF of 260 kV/cm in 4 mol % ACN-modified NBT-SBT ceramic. The first-principles calculation reveals that the interaction between Bi and O is the intrinsic mechanism of the increased polarization. A new parameter ΔP/Eb was proposed to be used as the figure of merit to measure the energy-storage performance under MEFs (∼200-300 kV/cm). This work paves a new way to explore energy-storage materials with excellent-performance MEFs.

Texture-based ferroelectric hardening in Na1/2Bi1/2TiO3 -based piezoceramics

${\mathrm{Na}}_{1/2}{\mathrm{Bi}}_{1/2}\mathrm{Ti}{\mathrm{O}}_{3}$-based (NBT-based) ceramics offer a viable option to replace lead-based materials for high-power applications as they are characterized by a stable mechanical quality factor with increasing vibration velocity in comparison to lead-based piezoceramics. Recently, the minor and stable extrinsic contributions were revealed as the origin for the stability of the mechanical quality factor with increasing vibration velocity. This work identifies the very unusual high poling degree as cause for the small extrinsic contributions. To this end, complete pole figure densities have been quantified and correlated to the piezoelectric coefficient and electromechanical quality factor. This hypothesis is further strengthened by correlating the piezoelectric constant (sum of intrinsic and extrinsic contributions) with the remanent polarization (correlates to remanent texturing degree). In order to assess a full picture of NBT-based piezoceramics, $0.94{\mathrm{Na}}_{1/2}{\mathrm{Bi}}_{1/2}\mathrm{Ti}{\mathrm{O}}_{3}\text{\ensuremath{-}}0.06\mathrm{BaTi}{\mathrm{O}}_{3}$ has been considered with and without Zn doping and with quenching. It is compared to $0.79{\mathrm{Na}}_{1/2}{\mathrm{Bi}}_{1/2}\mathrm{Ti}{\mathrm{O}}_{3}\text{\ensuremath{-}}0.21\phantom{\rule{0.16em}{0ex}}{\mathrm{K}}_{1/2}{\mathrm{Bi}}_{1/2}\mathrm{Ti}{\mathrm{O}}_{3}$ with and without Mg doping. Finally, a contrast to soft $\mathrm{Pb}({\mathrm{Zr}}_{1/2}{\mathrm{Ti}}_{1/2}){\mathrm{O}}_{3}$ (PZT) flushes out the impact of domain wall motion on the piezoelectric coefficient and the electromechanical quality factor. Whereas a PZT-based reference material exhibits a linear increase in the piezoelectric constant with increasing remanent polarization, the NBT-based materials deviate from the linear trend, indicating a decrease in extrinsic contributions.

Enhanced the energy storage performance of NBT-BY relaxor ferroelectric ceramics doped by STO

(1-x) (0.99 Na0.5Bi0.5TiO3-0.01BiYbO3)-x SrTiO3 (abbreviated as (1-x) (0.99NBT-0.01BY)-x STO) (x = 0.1⁓0.4) relaxor ferroelectric ceramics were fabricated by a solid-state reaction method. The crystal structure, surface morphology as well as dielectric, ferroelectric and energy storage properties of (1-x) (0.99NBT-0.01BY)-x STO were investigated in detail. X-ray diffraction patterns show that NBT-BY-STO ceramics have a single perovskite structure with a pseudo-cubic phase. The introduction of STO can effectively refine the NBT-based ceramic grain. The relaxation behavior of NBT-BY can be enhanced by incorporating moderate STO, and the impedance reduced with the increase of STO content. The results of hysteresis loop analysis indicate that incorporating STO into NBT-BY contributes to an increase in the electric breakdown field and a reduction in remnant polarization, thus enhancing its energy storage performance significantly. A moderate energy storage property with large Wrec (∼2.5 J/cm3) and high η (∼80.97%) was achieved at 260 kV/cm for x = 0.4. Meanwhile, 0.98(0.99NBT-0.01BY)− 0.2STO relaxor ferroelectric ceramic presented relatively good frequency and temperature stabilities of Wrec and η. This work provides an effective strategy for enhancing the energy storage performance of NBT-based relaxor ferroelectric ceramics applied in pulsed power devices.

The Influence of BaTiO3 Content on the Energy Storage Properties of Bi0.5Na0.5TiO3-Bi(Mg2/3Nb1/3)O3 Lead-Free Ceramics

Na0.5Bi0.5TiO3 (NBT)-based ceramics are promising lead-free candidates for energy-storage applications due to their outstanding dielectric and ferroelectric properties derived from large polarization. However, the high coercive field and large remnant polarization are unfavorable for practical applications, and thus NBT-based ceramics with relaxation behavior via doping/forming solid solutions with other elements/components have been widely studied. In this work, BaTiO3 (BT) was introduced to the 0.94Na0.5Bi0.5TiO3-0.06Bi(Mg2/3Nb1/3)O3 system by a conventional solid-state reaction to form a homogeneous solid solution of 0.94[(1−x)Na0.5Bi0.51TiO3-xBaTiO3]-0.06Bi(Mg2/3Nb1/3)O3 (BNT-100xBT-BMN). As the BT content increased, the proportion of the rhombohedral R3c phase increased while that of the tetragonal P4bm phase decreased, leading to the maximum Pmax (38.29 μC/cm2) and Eb (80 kV/cm) obtained in BNT-7BT-BMN (x = 0.07) composition. Specifically, the optimal energy storage properties of Wrec ~ 1.02 J/cm3 and η ~ 62.91% under 80 kV/cm were obtained in BNT-7BT-BMN ceramics, along with good temperature stability up to 200 °C, which are promising factors for future pulse power applications.

Study on vibrational Raman modes and electric properties of lead-free sodium bismuth titanate – bismuth magnesium zirconate piezoelectric ceramics

Raman spectra of lead- free piezoelectric sodium bismuth titanate-bismuth magnesium zirconate (1-x)(Na0.5Bi0.5)TiO3-xBi(Mg0.5Zr0.5)O3 [NBT-BMZ] ceramics are recorded and analyzed. Vibration phonon frequencies associated to Bi-O, Na-O, TiO6 octahedra and oxygen vibrations are noticed. Intensity changes on E(TO1) mode at 110 cm−1 arising from Bi-O vibrations is due to difference in polarizability of substituted cations in the A-site of NBT. Frequency shift in 247 and 281 cm−1 mode are attributed to lattice change and TiO6 octahedral rotation induced by substitution of BMZ in NBT. Increase of E(TO4) and A1(TO4) vibration modes due to decrease of TiO6 octahedral rotation reduces the lattice distortion and homogeneous strain which in turn prompts softening of coercive field and enhances remnant polarization as well as dielectric constant in NBT-BMZ piezoceramics. Also, vibrational Raman modes E(TO1), E(TO4) and A1(TO4) are the decisive phonons for interpreting the interesting dielectric behavior of NBT-based ceramics.

Dielectric temperature stability and energy storage performance of NBT-based lead-free ceramics for Y9P capacitors

In this work, novel (1 [Formula: see text])(0.75Na[Formula: see text]Bi[Formula: see text]TiO3)-0.25Sr(Zr[Formula: see text]Sn[Formula: see text]Hf[Formula: see text]Ti[Formula: see text]Nb[Formula: see text])O3-[Formula: see text]NaNbO3 (NBT-SZSHTN-[Formula: see text]NN, [Formula: see text] = 0.1, 0.15, 0.2, 0.25) ceramics were fabricated. The influence of co-doping of NN and high entropy perovskite oxide (SZSHTN) on the phase structure, microstructure and dielectric properties of NBT-based lead-free ceramics was investigated. Dense microstructure with a grain size of [Formula: see text]5 [Formula: see text]m is observed. When [Formula: see text] = 0.25, a wide dielectric temperature stable range of −35.4–224.3[Formula: see text]C with a low temperature coefficient of capacitance of [Formula: see text] 10% is achieved, fulfilling the industry standard of Y9P specification. Furthermore, excellent energy storage performance with recoverable energy density of 2.4 J/cm3, discharge efficiency of 71%, power density of 25.495 MW/cm3 and discharge rate [Formula: see text] 200 ns are simultaneously obtained, which shows great potential for high temperature capacitor applications.

Corrigendum to “Significant improvement in electrical characteristics and energy storage performance of NBT-based ceramics” [Ceram. Int. 48 (18) (2022) 26973–26983

Corrigendum to “Significant improvement in electrical characteristics and energy storage performance of NBT-based ceramics” [Ceram. Int. 48 (18) (2022) 26973–26983

Superior energy storage performance of < 001 > -oriented NBT-BY-STO relaxor ferroelectric textured ceramics

In this paper, < 001 > -oriented ternary NBT-BY-STO textured ceramics were prepared by tape casting technique based on composition design and orientation engineering strategies. The introduction of BY greatly reduces the grain size and increases the breakdown field strength, resulting in the improvement of the energy storage density. The relaxation behavior and saturation polarization of the ceramics were enhanced by < 001 > -orientation engineering, and so significantly increased energy storage density and energy storage efficiency. Finally, the energy storage performance of NBT-based ceramics was improved obviously. When x = 0.3, the energy storage density reached 5.34 J/cm3, and the energy storage efficiency was 83.91%. The prepared textured ceramics have excellent temperature, frequency stability and charge-discharge characteristics. Therefore, < 001 > -oriented ternary textured ceramics prepared in this paper is a potential dielectric material for pulse powder device, and this strategy of optimizing the energy storage performance also provides guidance of energy storage performance regulation for dielectric energy storage materials.

Energy storage and charge-discharge performance of B-site doped NBT-based lead-free ceramics

Dielectric ceramic materials with high energy-storage density and excellent charge-discharge performance are desirable for use in dielectric capacitors. In this study, (Na 0.5 Bi 0.5 ) 0.75 Sr 0.25 TiO 3 – x Nb 2 O 5 (denoted as NBSTN x ) lead-free ceramics were prepared by a solid-state reaction method. Polarization-electric field hysteresis loops ( P–E loops) reflected the energy storage characteristics of the NBSTN x ceramics. Introducing Nb into a pure NBST ceramic can reduce the large remnant polarization ( P r ) and make the P–E loops slimmer. Through repeated trials and calculations, the maximum recoverable energy-storage density ( W rec ~ 3.25 J/cm 3 ) and energy storage efficiency ( η ~ 74.5%) were achieved for the NBSTN 0.03 ceramic at 140 kV/cm. We also tested the stability performance of the NBSTN x ceramics, where the NBSTN 0.03 ceramic exhibited the highest thermal stability (30–100 °C) and frequency stability (10–1000 Hz). The NBSTN 0.03 ceramic also had a fast discharge rate (<300 ns) and a good discharge energy-storage density ( W d ~ 1.80 J/cm 3 ). Therefore, the NBSTN 0.03 ceramic with a good energy-storage density and charge-discharge performance has excellent application prospects for practical dielectric capacitors. • A strategy incorporating B-site doping to enhance energy storage performance. • A relatively high W rec of 3.25 J/cm 3 and η of 74.5%. • Sample with 0.03 mol Nb doping shows relatively good temperature and frequency stability.

An alternative way to design excellent energy-storage properties in Na0.5Bi0.5TiO3-based lead-free system by constructing relaxor dielectric composites

With growing concerns over environmental protection, lead-free dielectric ceramic capacitors are attracting much attention. In this work, a series of novel (1-x) Na0.5Bi0.5TiO3-x Ba5LaTi3Ta7O30 ((1-x)NBT-xBLTT) dielectric composite ceramics were fabricated by a traditional solid‐state method. All the samples possess a compact microstructure with refined grain morphology with increasing BLTT content, and tend to exhibit a diphase dielectric composite as x reaches up to 0.05. Furthermore, the addition of BLTT enhances the dielectric relaxor behavior of NBT-based ceramics, such that the x = 0.15 composite ceramic exhibits a typical feature of relaxor ferroelectrics. As a result, a high recoverable energy-storage density of Wrec~3.67 J/cm3, an ultrahigh energy-storage efficiency of η~97.3%, and a high power density of PD~333 MW/cm3 can be simultaneously obtained in the x = 0.15 relaxor composite ceramic. This study provides an alternative way to design excellent energy-storage performances in NBT-based compositions through constructing dielectric relaxor composites via introducing non-polar tungsten bronze oxides.

Enhanced energy storage performance and temperature stability achieved by a synergic effect in Nd3+/Ga3+ co-doped (Na0.5Bi0.5)TiO3 -based ceramics

(1-x)(0.75(Na0.5Bi0.5)TiO3-0.25SrTiO3)-xNdGaO3 ceramics (NBST-xNG, x = 0–0.06) were fabricated through a solid-state reaction method. High-valent Nd3+ ions enter the perovskite A-site to occupy Bi vacancies resulting from the volatilization of Bi, inhibiting the formation of oxygen vacancies and contributing to an enhanced breakdown electric field (Eb). Low-valent Ga3+ ions enter the B-site to substitute for Ti4+ ions, resulting in the formation of random electric fields (REFs) at the B-site due to co-occupying hetero-valence ions of Ga3+/Ti4+, which significantly reduces ferroelectric hysteresis. Therefore, a synergic effect of A- and B-sites co-doping was realized in NBST-xNG ceramics. Benefitting from this synergic effect, an enhanced recoverable energy storage density (Wrec) of 2.88 J/cm3 and an efficiency (η) of 83% are simultaneously obtained in NBST-0.04NG ceramics under a moderate electric field (E) of 200 kV/cm. Compared with most NBT-based ceramics, the values of (η vs Wrec/E2) for NBST-0.04NG ceramics show an obvious advantage, indicating excellent potential for application as an energy storage material. Moreover, Wrec and η of NBST-0.04NG ceramics exhibit excellent temperature stability from 30 °C to 200 °C due to the enhanced correlation strength of polar nanoregions (PNRs) and local structural stability. This work provides a potential strategy to improve the energy storage performance of NBT-based ceramics via the synergic effect of A- and B-site co-doping.