Recoverable Energy Research Articles

Influence of sintering temperature on the electrical properties of SrTiO3–BaZrTiO3 ceramics for energy storage applications

The impact of the sintering temperature on the phase composition and electrical properties of 5%SrTiO3–95%BaZr0.15Ti0.85O3 (ST-BZT) ceramics fabricated by solid-state method and consolidated by two-step sintering is presented. A systematic analysis of the phase composition, microstructures, dielectric, ferroelectric, and energy storage characteristics. A di-phase SrTiO3–BaZrTiO3 composite is obtained at low sintering temperatures below 1400 °C. Increasing the sintering temperature causes a shift of the Curie temperature from 62 °C to 55 °C together with changes of permittivity values and of the ferroelectric loops, thus indicating a progressive interdiffusion process at the interfaces, together with a better densification. Remarkably, the ST-BZT composition sintered at 1500 °C exhibits characteristics of a single phase (Ba,Sr) (Zr,Ti)O3 solid solution, with high room temperature permittivity around 2950 and good ferroelectric response (saturation polarization Pmax = 12.6 μC/cm2 and remnant polarization Pr = 2.16 μC/cm2). Consequently, this composition displays a much greater recoverable energy density (Wrec = 54.5 mJ/cm3) in comparison to the ones of the di-phase ST-BZT composites and the parent phases. However, the (Sr0.05Ba0.95) (Zr0.14Ti0.86)O3 solid solution, demonstrates a lower energy efficiency (72%) in comparison to the ST-BZT di-phase composites sintered at lower temperatures, which exhibit higher energy efficiency values around 86%. In addition, the charge-discharge experiments were performed under different electric fields to disclose the difference in energy storage properties in 5%SrTiO3–95%BaZr0.15Ti0.85O3 ceramics. This suggests that the sintering strategy plays a crucial role in determining the energy efficiency of the obtained ceramics. Additionally, all the investigated ST-BZT ceramics present high energy efficiency at low-applied electric fields, suggesting their potential as candidates for energy storage capacitors operating at moderate fields.

A Flexibly Function‐Oriented Assembly Mechanical Metamaterial

AbstractBased on the snap‐through instability, the pursuit for mechanical metamaterials with flexible functional applications and the ability to combine with information has been the Holy Grail for structural scientists. Here, the function/application‐oriented bistable unit motifs (UMs) are developed by an elaborately architectural design inspired by the hind leg of the frog in jumping, and a corresponding assembled strategy is proposed. Three functional applications derived from their progressive evolutions. The first is the construction of on‐demand assemblable mechanical curves, including multi‐stage vibration isolation, recoverable energy absorption, and energy dissipation along with integrated vibration isolation and energy dissipation characteristics. The second is the development of mechanic and temperature double pattern encryption strategy using bistability and shape memory programmability, resulting in 4n encryption and decryption modes for n‐bit encryption devices. Finally, five non‐volatile basic mechanical logic gates and a universal combinatorial half‐adder are built, affording guidance to unconventional computing devices with logic functions.

Excellent Energy Storage Performance of ZnO doped (Pb,La)(Zr,Sn,Ti)O3 Based Antiferroelectric Ceramics at an Ultra‐Low Sintering Temperature of 940 °C

Abstract(Pb,La)(Zr,Sn,Ti)O3‐based antiferroelectric ceramics have excellent energy storage performance(more than 90% efficiency), which make them have great application advantages in the field of ceramic capacitors. However, the sintering temperature of (Pb,La)(Zr,Sn,Ti)O3‐based antiferroelectric ceramics is generally above 1250 °C, which limits application as a material for ceramic capacitors. Cu inner electrode has a low co‐firing temperature and high conductivity and a low cost price, making it more competitive in the field of ceramic capacitor inner electrode. Therefore, the first step is to reduce the sintering temperature of (Pb,La)(Zr,Sn,Ti)O3‐based ceramics to below 1000 °C(co‐firing temperature with Cu inner electrode), which is the key and difficult point. In this paper, Pb0.94La0.02Sr0.04(Zr0.45Sn0.47Ti0.08)0.995O3(PLSZST) antiferroelectric ceramics are doped with ZnO, which effectively reduce the sintering temperature. Among them, PLSZST‐1 wt% ZnO is sintered at an ultra‐low sintering temperature (TSintering = 940 °C), which is 330 °C lower than that of PLSZST(TSintering = 1270 °C) without doping ZnO. At the same time, PLSZST‐1 wt%ZnO obtain a recoverable energy density of 4.26J cm−3 and an energy efficiency of 95.5% at 230 kV cm−1. The pulse discharge energy density (Wdis = 3.92 J cm−3) and discharge time (t0.9 = 351 ns) are obtained at 220 kV cm−1, and the current density (CD = 1338A cm−2) and power density (PD = 134MW cm−3) are obtained at 200 kV cm−1. The results provide a possible material basis for Cu internal electrode ceramic capacitors.

Low-temperature stable ferroelectric–antiferroelectric transition for cryogenic energy storage application

The capacitors are in rising demand for cryogenic applications. As for now, it still remains an ongoing challenge for simultaneously achieving high energy storage density and cryogenic temperature stability. Herein, the strategy of stable backward phase transition was demonstrated in the antiferroelectric composition of (Pb0.9175La0.055)(Zr0.975Ti0.025)O3. As a result, we achieved high recoverable energy density about 10 J/cm3 with exceptional low-temperature stability from −160 to 25 °C. Multi-layer ceramic capacitors designed for pulse discharge applications also demonstrated high performance in cryogenic conditions, with the peak current fluctuations of less than 4%. Through in situ characterizations using x-ray diffraction, Raman spectra, and transmission electron microscopy, we discovered that the anisotropic structural evolution is responsible for a stable backward phase transition, providing the material with robust stability at cryogenic temperatures. These results offer a good paradigm for improving the temperature stability of antiferroelectric multi-layer capacitors to meet the rigorous demands of energy storage applications.

Excellent energy storage performance of lead-based antiferroelectric ceramics via enhancing dielectric breakdown mechanism

Lead-based antiferroelectric (AFE) material with high power density has received extensive attention for potential applications in the energy storage devices. Nevertheless, the presence of a secondary phase reduces the band gap and concentrates a significant localized electric field at the center of the tips of both secondary phases, leads to a poor breakdown electric strength (Eb). Hence, we designed high Eb of (Pb1-1.5xSmx)(Zr0.995Ti0.005)O3 ceramics with high energy performance via enhancing dielectric breakdown mechanism by restraining secondary phase. Density functional theory calculations reveal that the valence and conduction bands of secondary phase are in close proximity to the Fermi level, indicating the smaller band gap of secondary phase is unable to withstand the concentration of local electric fields in this samples, thus leading to obtain a poor Eb. UV–vis absorption spectra experiments demonstrate that the overall band gap increases due to the A-site Sm modification strategy, effectively reducing the secondary phase and resulting in elevated levels of Eb. As a consequence, Eb is remarkably improved from 350 kV/cm into 540 kV/cm with increasing Sm3+ content. A record-high Eb of 520 kV/cm and high recoverable energy storage density of 12.9 J/cm3 (energy efficiency of 77.1 %) are achieved in (Pb0.91Sm0.06)(Zr0.995Ti0.005)O3 (PS6ZT) ceramics by tape-casting method. Concerning the performance of pulse charge–discharge, ultrahigh discharge energy density of 8.5 J/cm3 and excellent power density of 188.53 MW/cm3 are achieved in PS6ZT ceramics. Moreover, outstanding stability behavior with a broad frequency range of 1∼140 Hz and a broad temperature range of 20–120 ℃ are obtained. These results show that enhancing Eb mechanism will be provided a potential option to enhanced energy density for PbZrO3-based AFE ceramics.

High energy storage performance of (1-x)Ba0.5Sr0.5TiO3-xK0.5Na0.5NbO3 ceramics via a combined strategy of fine grains and multiphase polar nanoregions

Electrostatic dielectric capacitors have received great attention due to their ultrafast charging-discharging speed and ultrahigh power density. However, the low energy storage density and efficiency are the main obstacles to their practical applications. In this work, solid solution relaxor ceramics with different proportions of lead-free ferroelectrics Ba0.5Sr0.5TiO3 (BST) and K0.5Na0.5NbO3 (KNN) were prepared. Superior energy storage performance was achieved in the 0.7BST-0.3KNN ceramics with a breakdown strength (Eb) of 510 kV/cm, a recoverable energy storage density (Wrec) of 4.10 J/cm3, and an energy storage efficiency (η) of 80 %, which was fairly stable over the temperature range of 30–100 °C. Since multiple cations with different valence and radius coexist on the equivalent sites (A or B sites) of the solid solutions, the chemical disorder and the corresponding lattice distortion induced the coexistence of cubic, tetragonal, and orthorhombic phases, as well as the appearance of the multiphase polar nanoregions (PNRs), making the ferroelectric hysteresis loops linear. At the same time, ultrafine grains in the ceramics greatly improved the Eb. For achieving excellent energy storage performance, this work demonstrates a potential candidate of (1-x)BST-xKNN lead-free solid solution ceramics and a combined strategy of fine grains and multiphase PNRs.

Bi0.5Na0.5TiO3-based energy storage ceramics with excellent comprehensive performance by constructing dynamic nanoscale domains and high intrinsic breakdown strength

Lead-free ceramic-based dielectric capacitors show huge potential in electrical energy storage in pulsed power systems due to their fast charge/discharge rate, ultrahigh power density and environmental friendliness. However, unsatisfied charge/discharge performance characterized by inferior recoverable energy storage density (Wrec generally <5 J/cm3) has become a key bottleneck to restrict their applications in cutting-edge energy storage devices. In this paper, we focus on simultaneously realizing ultrahigh Wrec and efficiency (ƞ) in eco-friendly Bi0.5Na0.5TiO3 (BNT)-based dielectric ceramics via chemical doping. Interestingly, highly dynamic polar nanoregions (PNRs) and nanodomains are constructed by incorporating Sr0.7Nd0.2TiO3 (SNT) into 0.94BNT-0.06BaTiO3. Of great importance, the resulting relaxor ferroelectrics (RFEs) exhibit high bulk resistivity, submicron grain size and wide band gap due to high level of SNT doping accompanying with 1 at% Nb donor doping. Therefore, excellent energy storage properties with ultrahigh Wrec∼8.08 J/cm3 and ƞ∼92.1% are achieved due to coexistence of large polarization difference (ΔP=Pmax−Pr) and giant dielectric breakdown electric field (Eb∼540 kV/cm). Furthermore, excellent temperature/frequency/cycling stability characterized by ΔWrec < ±4% and Δη < ±2% ensure the energy storage applications of the studied dielectric ceramics over an enormous range of scales.

Enhancing energy storage performance of polyethylene via passivation with oxygen atoms through C–H vacancy carbonylation

Low energy density of polymer film capacitors is regarded as one of the most serious drawbacks facing growing demands for equipment integration and miniaturization. Herein, ultraviolet light and ozone (UVO) surface modification is utilized to simultaneously improve dielectric constant and breakdown strength of polyethylene (PE) films. As a result, after 3 min of UVO treatment, an enhanced recoverable energy density of 4.79 J/cm3 with a charge-discharge efficiency of >95% is obtained under 650 MV/m at room temperature (RT). Significantly, stable energy storage performance under 200 MV/m is maintained throughout a broad temperature range from −90 °C to 90 °C and during 20,000 cycles of charge-discharge procedures. According to first-principles calculations and thermally stimulated depolarization current measurements, formation of carbonyl groups (C=O) after UVO treatment could effectively passivate initial deep-level defect states caused by H vacancies, which explains the improvement in capacitive energy storage. Moreover, the metalized UVO-modified PE exhibits valuable breakdown self-clearing ability, and the self-cleared specimen maintains stable energy storage performance over 20,000 cycles at 200 MV/m and RT. This work offers an effective and user-friendly method for enhancing comprehensive dielectric characteristics of PE-based materials and potential for applications in modern power systems and electronic devices.

Engineering Phase Separation in Niobate Glass through Ab Initio Molecular Dynamics for Enhanced Energy Storage Performance and Unprecedented Thermal Stability in Niobate-Based Glass Ceramics.

The advancement of lead-free glass ceramics (GCs) possessing appropriate energy storage characteristics is crucial for the renewable energy and electronics industry. In this study, we synthesized lead-free GCs predominantly composed of the tungsten bronze phase, Ba3.3Nb10O28.3. Ab initio molecular dynamics initially reveal nonuniform distribution within the Ba/Nb-O regions in niobite glassy melts, offering valuable insights for the subsequent crystallization process. The proposal of a B-site engineering strategy is suggested, which entails the concurrent reduction of grain size and augmentation of the band gap in tungsten bronze GCs doped with Ta. This approach results in a substantial enhancement of the dielectric breakdown strength (BDS). Phase-field simulations have indicated that the refinement of grain sizes plays a pivotal role in augmenting the local electric field distribution and breakdown path, thereby contributing to the enhancement of BDS. As a consequence of these modifications, a notably high recoverable energy density (Wrec) of 5.23 J/cm3 can be achieved, accompanied by an ultrahigh efficiency (η) of 94%, and superior thermal stability in energy storage. These outcomes are particularly evident in the case of 2 mol % Ta2O5-doped P2O5-K2O-BaO-Bi2O3-TeO2-Nb2O5 (PKBBTN-T) GCs, where the Wrec and η can be determined to be 2.87 ± 3% J/cm3 and 95.46 ± 4%, respectively, over a temperature range spanning from 20 to 150 °C. Additionally, this specimen exhibits an exceptionally high discharge energy density (Wdis) of 4.01 J/cm3. This comprehensive investigation, comprising experimental and theoretical analyses, establishes an effective pathway and paradigm for the development of dielectric materials with ultrahigh energy storage properties.

Enhanced recoverable energy storage density and breakdown strength in cation-site modified K0·5Bi0·5TiO3-based ergodic relaxor ferroelectric

Bi-containing ferroelectrics like Na0·5Bi0·5TiO3 (NBT) and K0·5Bi0·5TiO3 (KBT)-based materials are extensively investigated to achieve high recoverable energy storage density (Wrec) and efficiency (η). In this work, Bi-site modified KBT-based compositions have been studied for energy storage application at room temperature. KBT has been transformed from a non-ergodic to an ergodic relaxor state through the Eu3+ substitution. High breakdown voltage and slim polarization vs electric field loop are observed in 6 mol% Eu3+-substituted KBT, and high maximum polarization (Pmax) is retained along with low remnant polarization (Pr) in this composition. These features help to attain the Wrec and efficiency of 1.3 J/cm3 and 72%, respectively in 6 mol% Eu3+-substituted KBT at room temperature. This work demonstrates a strategy to enhance the Wrec and η by forming a stable ergodic relaxor state in the KBT-based material.

Enhanced energy storage properties of (Ba0.4Sr0.6)TiO3 ceramics with ultrahigh energy efficiency through doping of Bi0.2Sr0.7(Mg1/3Nb2/3)O3

Dielectric (Ba0.4Sr0.6)TiO3 (BST) ceramics are promising dielectric energy storage materials due to their moderate dielectric constant, low dielectric loss, and slight nonlinearity. However, their energy density is limited by their low breakdown strength (BDS). In this study, we aimed to address this limitation by incorporating various amounts of Bi0.2Sr0.7(Mg1/3Nb2/3)O3 (SBMN) into the BST matrix. The (1–x)BSTxSBMN ceramics were prepared by conventional solid-state sintering, resulting in single-phase solid solutions. Compared to pure BST ceramics, the (1–x)BST–xSBMN ceramics exhibited lower remnant polarization and significantly enhanced BDS. Furthermore, the relaxation of the ceramics enhanced with increasing doping concentration, with an efficiency of η = 94.0% achieved at x = 0.20. Among them, the breakdown field strength of 0.85BST–0.15SBMN ceramics was 597 kV cm−1, achieving a recoverable energy storage density of Wrec = 2.81 J cm−3 and an efficiency of η = 90.8% under an external electric field of 480 kV cm−1. Subsequent tests revealed that the introduction of SBMN not only increased the band gap and conduction activation energy of the material, leading to an increase in BDS, but also promoted the formation of polar nanoregions (PNRs) which contributed to boosted energy efficiency, resulting in a significant enhancement in the energy storage performance of BST ceramics.

Mass-composite activation energies for recycled binder blends

Using reclaimed asphalt pavement (RAP) has become an appealing development for economic and environmental benefits. One of the key issues when incorporating RAP materials is to ensure the performance of recycled binder blends. Despite extensive researches dealing with physical and chemical aspects, concerns about recycled materials combinations remain. This paper focuses on the kinetics of aging, cracking and healing process for blended binders with a novel hypothesis of mass-composite activation energies. Firstly, four blends were prepared with different ratios of virgin bitumen and laboratory-produced RAP binders. Then, Fourier-transform infrared spectroscopy was utilized to track the carbonyl formation in all samples initially and with aging, and aging activation energy (Eacr) was computed in terms of Arrhenius equation. Thirdly, strain-controlled oscillatory measurements were conducted; moreover, representative energy change rates of dissipated pseudo strain energy and recoverable strain energy were obtained to determine the activation energy for cracking (Eac) and healing (EaH), respectively. Finally, hypotheses of mass-composite activation energies were validated with the test results. It shows that Eacr of recycled binder blends are smaller than that of RAP binders, indicating a lower kinetic barrier to oxidation reaction for blended bituminous system. With the increase of RAP binder content, the blends exhibit a decrease in Eac and an increase in EaH, which reveals the adverse effect introduced by oxidation in cracking resistance and healing capability. Excitingly, the measured activation energies of recycled binder blends are consistent with the calculated mass-composite activation energies, which will hopefully provide support for performance estimation.

Fulfilling X9R specification in CeO2 modified BNBST-based relaxor ferroelectric energy storage ceramic capacitors

Future low-voltage driven capacitor devices are appealed to employ the eco-friendly ceramics featured with high-stable dielectric energy storage capabilities. Herein, the dielectric energy storage properties of (Bi0·5Na0.5)0.65(Ba0·3Sr0.7)0.35(Ti0·98Ce0.02)O3+8 wt% K0·5Na0·5NbO3+x wt% CeO2 (BNBSTCK + Cx) lead-free relaxor ferroelectric ceramics were comprehensively investigated. By maintaining the relaxor ferroelectric phases near room temperature and disrupting the ferroelectric long-range order via CeO2 additive, the EIA X9R specification was fulfilled at the best composition of x = 8 over a wide range of −74∼208 °C with a relatively high dielectric constant εr = 904 and low loss tanδ = 10−3 (@25 °C & 1 kHz). Meanwhile, the good recoverable energy storage density Wrec = 0.77 J/cm3 and high efficiency η = 91.6% were achieved only at a low electric field of 95 kV/cm. Furthermore, these ceramics exhibited exceptional frequency and cycle dependent energy storage stability, which could guide the design ideas of long-life X9R ceramic capacitors suitable for high and low working temperature environments in low-voltage driven energy storage applications.

Ni-modified BaTiO3 film prepared by sol-gel with high energy storage performance

The development of lead-free dielectric capacitors with high recoverable energy storage density and high energy storage efficiency is important for improving the overall performance of electronic and power systems. BaTiO3 (BTO) is one of the most common ferroelectric materials and has attracted much attention for energy storage applications in the past decades due to its excellent dielectric and ferroelectric properties. However, high remnant polarization and low electrical breakdown strength of BTO limit its development in energy storage applications. Many efforts (e.g., elements doping, interface/heterostructure, etc.) have been made to improve the energy storage density of BTO thin films. In this paper, Ba1-xNixTiO3 thin films (x = 0, 0.02, 0.04, 0.06, 0.08; abbreviated as BNxT) were synthesized via sol-gel and spin-coated method. The effect of Ni doping on the structural, dielectric, ferroelectric and energy storage properties of BTO thin films has been studied. The results confirmed that with the increase of Ni doping, a second phase arises and the dielectric constant decreases. While appropriate Ni doping led to the improvement of the breakdown strength, further increase of Ni deteriorated the energy storage because of the high oxygen vacancy. Finally, optimized energy storage performance was obtained for BN0.04T thin film: dielectric constant of 401, dielectric loss of 0.002, recoverable energy density of 20.2 J/cm3 and energy storage efficiency of 83.6% at 965 kV/cm. Meanwhile, the remnant and maximum polarization of the films were 0.06 μC/cm2 and 50 μC/cm2, respectively. BN0.04T thin film has an excellent application prospect and is expected to appear as a component in the future composite energy storage film system.

Samarium-modified PLZST-based antiferroelectric energy storage ceramics for low-temperature sintering in reducing atmosphere

The energy storage properties of pure PLZST-based antiferroelectric ceramics are excellent; however, the high sintering temperature renders them unsuitable for co-firing with copper inner electrodes as MLCC dielectric materials. The proven BASK glass additive was employed in this study to lower the sintering temperature of PLSZT ceramics, while simultaneously doping Sm3+ ions to enhance their sintering performance under reducing atmospheres. The precise evaluation process confirmed that the addition of glass effectively reduced the sintering temperature to 1040 °C. Furthermore, the defect association of Sm3+ doping hindered the formation of oxygen vacancies, facilitated ceramic grain growth, and significantly enhanced insulation resistivity. Consequently, an ultrahigh recoverable energy density (Wrec) of 5.19 J/cm3 with a high energy storage efficiency (η) of 94.5% are achieved at an electric field of 430 kV/cm. Moreover, the AFE ceramics possess excellent discharge energy storage properties with a high discharge energy density (Wd) of 4.26 J/cm3 and a large power density (Pd) of 139 MW/cm3.

Superior energy storage and discharge performance achieved in PbHfO3-based antiferroelectric ceramics

Dielectric capacitors prepared by antiferroelectric (AFE) materials have the advantages of large power density and fast discharge ability. It has been a focus on the improvement of the recoverable energy density (Wrec) and discharge energy–density (Wdis) in the AFE ceramics. To address the above issue, optimizing the proportion of components is proposed for enhancing ceramic antiferroelectricity, ultimately improving the breakdown strength (Eb) and Wrec. In this work, an ultrahigh Wrec (14.3 J/cm3) with an excellent energy efficiency (η) of 81.1% is obtained in (Pb0.96Sr0.02La0.02)(Hf0.9Sn0.1)O3 AFE ceramic at electric field of 490 kV/cm, which is the maximum value reported in lead-based AFE ceramics fabricated by the conventional solid-state reaction method so far. The multistage phase transition induced by the electric field is observed in the polarization–electric field (P–E) hysteresis loops. Furthermore, an outstanding power density (PD) of 335 MW/cm3 and an excellent Wdis of 8.97 J/cm3 with a rapid discharge speed (102 ns) are obtained at electric field of 390 kV/cm. In addition, (Pb0.96Sr0.02La0.02)(Hf0.9Sn0.1)O3 ceramics also possess an excellent thermal and frequency stability. These exceptional properties indicate that (Pb0.98−xSrxLa0.02)(Hf0.9Sn0.1)O3 ceramics are a potential candidate for pulsed power devices and power electronic devices.

Enhanced energy storage performance of (Bi0·4Ba0·2K0·2Na0.2)TiO3–NaNbO3 high-entropy ceramics under moderate electric fields

High-entropy perovskite oxides (HEPOs) have attracted considerable attention as dielectric ceramics. However, the energy-storage performance of these HEPOs still requires improvement. In this study, a series of (1-x)(Bi0.4Ba0.2K0.2Na0.2)TiO3-xNaNbO3 high-entropy ceramics were designed and prepared using a high-entropy strategy. The introduction of antiferroelectric NaNbO3 into the (Bi0.4Ba0.2K0.2Na0.2)TiO3 medium-entropy matrix increased the configurational entropy and cationic disorder, resulting in improved energy storage performance. The ceramic with an optimal composition of 0.775(Bi0.4Ba0.2K0.2Na0.2)TiO3-0.225NaNbO3 achieved a high recoverable energy density (Wrec) of 2.523 J/cm3 and a high efficiency (η) of 83.7% at an electric field of 220 kV/cm. Furthermore, the material demonstrated good temperature and frequency stability, as well as good anti-fatigue properties. This paper presents a dielectric ceramic suitable for energy storage under low to moderate electric fields.

Advancing energy storage capabilities in 0.7BNST(1-x)-0.3BLMNx lead-free dielectric ceramic materials

Lead-free ferroelectric ceramics with a composition of 0.7(Bi0.5Na0.5)0.7Sr0.3Ti(1-x)O3-0.3Ba0.94La0.04(Mg1/3Nb2/3)xO3 (abbreviated as 0.7BNST(1-x)-0.3BL(MN)x, 0 ≤ x ≤ 0.12) were prepared using solid-phase sintering method, involving co-substituting at A and B sites. High recoverable energy density (Wrec) of 3.54 J/cm3 and energy efficiency (η) 85.49% are achieved at an electric field of 270 kV/cm. Furthermore, these ceramics exhibited excellent temperature and cycle stability at 120 kV/cm (within 25 °C–150 °C, Wrec fluctuation range <14 %; under 1∼106 cycles, the Wrec fluctuation range <5 %). In terms of dielectric performance, they exhibited a high dielectric constant (εr∼4540), an extremely low dielectric loss tanδ of <0.04 (30 °C–300 °C), and good temperature stability with Δε/ε150 °C ≤ ±15 % (−19.5 °C–233.4 °C). During the charging and discharging process, these ceramics demonstrated a high energy density (Wd) of 1.2 J/cm3, a power density (PD) of 61.7 MW/cm3, and an extremely short discharge time (t0.9) of approximately ∼0.11 μs＀ This study has improved the dielectric energy storage performance of BNT-based lead-free piezoelectric ceramics, making them suitable for use in pulse power devices.

Enhanced energy storage and temperature-stable dielectric properties in (1-x)[(Na0.4K0.1Bi0.5)0.94Ba0.06TiO3]-xLa0.2Sr0.7TiO3 lead-free relaxor ceramics

With the continuous growth in sustainable and renewable technologies, ceramic capacitors are emerging as a promising energy storage device. Lead-free (1-x)[(Na0.4K0.1Bi0.5)0.94Ba0.06TiO3]-xLa0.2Sr0.7TiO3 (0 ≤ x ≤ 0.40) ceramics were prepared using the solid-state reaction technique for obtaining relaxor characteristics with improved energy storage density, efficiency, and temperature stability of dielectric permittivity. A high recoverable energy density (Wr) ∼ 2.39 J/cm3 with a good efficiency (η) of ∼ 75.21% was obtained for x = 0.30 composition under 220 kV/cm applied field. The specimen x = 0.30 exhibited excellent fatigue resistance during 105 cycles and good temperature stability of energy storage characteristics (Wr > 0.87 J/cm3, η > 74%) in the temperature range of 25–180 °C under 100 kV/cm. In addition, the temperature range in which the dielectric permittivity variation was less than ±15% was very wide (204 °C (63–267 °C) and 275 °C (39–314 °C) for x = 0.30 and 0.20 specimens, respectively). Significant improvements in material performance were attributed to A-site engineering, which resulted in a mixture of P4bm and R3c polar nano regions (PNRs), leading to reduced hysteresis loss and temperature-stable dielectric permittivity. Additionally, the size of PNRs ranged between 3 and 6 nm, with the P4bm phase dominating in the x = 0.30 specimen, leading to a large maximum polarization under an applied electric field. Therefore, (1-x)[(Na0.4K0.1Bi0.5)0.94Ba0.06TiO3]-xLa0.2Sr0.7TiO3 relaxor ceramics are promising for high energy density materials and electronic applications requiring high permittivity stability over a wide temperature range.

Harnessing Bangladesh's Undeveloped Geothermal Potential: A Case Study of the Barapukuria Coal Basin

Despite its vast potential, geothermal energy still needs to be tapped in Bangladesh. This study addresses this gap by employing a data-driven, systematic approach to evaluate the Barapukuria Coal Basin as a candidate reservoir for the nation's first geothermal power plant. While existing research mainly focuses on resource identification, this work utilizes geotechnical data from the well-studied Barapukuria region to conduct a comprehensive and thorough analysis. The aim is to quantify the available geothermal power and assess the project's lifetime, energy output, and capacity. The methodology leverages the high geothermal gradient (&gt;48°C/km) observed in the area and existing information on reservoir and fluid properties. This enables the estimation of the recoverable thermal energy and subsequent validation of geothermal system models with empirical data. With no operational or planned geothermal plants in Bangladesh, this study represents a crucial step toward unlocking the resource's potential. The initial results are promising, suggesting the Barapukuria basin is a viable location for transitioning toward cleaner baseload power generation.