Pulsed Power Devices Research Articles

A pulse power supply module for launching fire extinguishing bombs

Abstract Electromagnetic launching technology has a wide range of applications and can replace conventional launching technology in many fields. In order to expand the application of this technology, the design of an induction coil type launcher that can launch fire extinguishing bombs, large-scale simulated bird bodies and other thrown bodies was completed, consisting of a four-stage coil capable of launching 10kg thrown body at an initial velocity of more than 100m/s. In order to meet the integration requirements of the launcher body, the design of a compacted pulsed power module matched to the launcher was carried out. According to the characteristics of multi-stage coil launching, the pulse discharge circuit is designed by adopting the continuity-front type topology to avoid the possible problem of induced voltage damage to the device; based on the technical specifications of the launcher, the types and parameters of the pulse power devices in the module are determined and the launch simulation is carried out for verification; measures such as high specific energy devices, shared electrodes structure, and built-in discharge devices are adopted to make the module meet the compactness requirements. The module has a rated energy storage capacity of 100kJ, a maximum operating voltage of 10kV, and a specific energy of 1.2MJ/m3. The short circuit discharge experiment and the coil discharge experiment shows that the module’s discharge capacity and structural strength satisfy the design requirements; and the actual launching experiment shows that four modules of the same type are used as the excitation source of the coil-type launcher, which can project a 10kg thrown body with an initial velocity of 103m/s at an operating voltage of 8kV.

Enhanced energy storage performance of NaNbO3-based ceramics by modifying phase structures and electrical insulation

The remarkable polarization and stability of ceramic capacitors make them promising candidates for pulse-power devices in energy-storage systems. However, the energy-storage density of ceramic capacitors is severely limited by the negative correlation between the maximum polarization (Pm) and the breakdown strength (BDS), leading to the impediment of broader applications. Herein, we reconcile the contradiction by synthesizing high-performance NaNbO3-based ceramics via chemical doping with Bi(Ni0.5Ti0.25Zr0.25)O3 (BNTZ). An antiferroelectric-paraelectric phase transition with a decline in polarization hysteresis is induced by the dopant. Further studies have shown that the existence of a tiny quantity of the polar phase in the nonpolar matrix contributes to a higher Pm, and the enhancement of both electrical resistivity and activation energy of the conductance also improved their BDS. The thinning process is also identified to be important in the improvement of its BDS and Wrec, resulting in the maximum energy-storage density of 3.53 J/cm3 with an energy efficiency of 74.2 % in thinned 10 mol% BNTZ-doped NaNbO3 samples. Our findings provide a feasible approach to simultaneously improving energy-storage density and efficiency in NaNbO3-based ceramic capacitors.

Impact of overvoltage on the mode transition of the spark gap switch: from edge breakdown to stochastic breakdown

Abstract Spark gap switch (SGS) is a fundamental but critical component for large-scale pulsed power devices, whose reliable operation is significantly affected by the breakdown characteristics of SGS. It is observed experimentally that, with the increase of overvoltage, the bridging position of the spark channel transits from edge to stochastic center. In this work, the influence of overvoltage on the breakdown process of a parallel-plate SGS with low geometric distortion of static electric field (<13%) between an atmospheric-pressure air gap of 5 mm is investigated by particle-in-cell/Monte Carlo collision simulation. It is found that, under a low overvoltage (ratio of applied voltage U a to static breakdown voltage U 0, U a/U 0 = 1.5), the streamers at the edge first bridge the gap before that in the central region, due to the field enhancement induced by the electrode curvature. Under higher overvoltage (U a/U 0 = 3), the synchronicity between streamers initiating from the center and those from the edge is greatly improved during the inception stage. After the streamers pass the middle of the gap, the field enhancement at the streamer front is more intensified and promotes the generation of fast electrons. These fast electrons rapidly magnify the difference among the propagating streamers by providing abundant seed electrons ahead of the discharge channel, which leads to the randomness of the bridging position. The results in this work demonstrate the relationship between overvoltage and streamer dynamics, which is beneficial for the performance improvement of SGS.

Superior energy storage performance in Bi0.5Na0.5TiO3 based ceramics via synergistic design of multi-size domain construction and multiple phase structures

Lead-free dielectric ceramics, as the crucial materials for the development of eco-friendly high pulse power devices, have faced limitations in achieving energy storage performance comparable to lead-based counterparts. A novel strategy was adopted to enhance the energy storage capability of Bi0.5Na0.5TiO3 based ceramics by constructing multiple phase structures and multi-size domain. An ultrahigh energy storage density of 8.0 J·cm−3 and a large efficiency of 88.9 % were achieved. The superior energy storage properties can be attributed to the synergistic effects of multiple phase structures and multi-size domain construction resulted from a significant polarization intensity difference upon Sr(Zr0.2Ti0.8)O3 doping. Even more surprising, the 0.6Bi0.5Na0.5TiO3-0.4Sr(Zr0.2Ti0.8)O3 ceramic exhibited excellent aging resistance, with variation in discharge energy density (Wd) < ±7% over a temperature range from 20 to 150°C, variations in recoverable energy density (Wrec) < ±8.3 %, and efficiency (η) < ±5.6 % over a frequency range from 1 to 50 Hz and across 105 cycles. The finding in this work not only provides an effective candidate for high power pulse capacitors, but also provides ideas for the study of high energy storage performance of BNT and the related lead-free ceramics.

Theory and simulation of the electrothermal instability in pulsed power electrode plasmas

Linear theory of the electrothermal instability is rederived and applied to conditions expected in pulsed power electrode surface plasmas comprised of either hydrogen or carbon. The analysis includes losses due to Coulomb collisions, inelastic processes derived from a collisional radiative model, and thermal conduction. The predicted growth rates are relevant for pulse durations typical of pulsed power devices. Linear theory reveals that the growth rate peaks at a characteristic wavenumber kmax, which is dependent on electron current density Je, number density ne, and temperature Te. Analysis of nonlinear simulations finds that saturation occurs as a result of Coulomb collisions, which limit the electron temperature to go no lower than the ion temperature such that Te≳Ti. When the instability is driven by a perturbation with broadband sinusoidal content, the peak in the energy spectrum nonlinearly shifts away from kmax toward smaller wavenumbers (or longer wavelengths) during saturation. The ETI is shown to be capable of driving plasma filaments with perturbed current densities and electron temperatures that exceed the initial, steady-state values.

Simultaneous Improvement of Energy Storage Characteristics and Temperature Stability in K0.5Na0.5NbO3-Based Ceramics via LiF Modification.

The splendid energy storage performances with eminent stability of dielectric ceramics utilized in pulsed power devices have been paid more attention by researchers. This scheme can be basically realized through introducing Li+, Bi(Mg2/3Ta1/3)O3, NaNbO3, and LiF into KNN-based ceramics. Under the breakdown strength (BDS) of 460 kV/cm, an outstanding energy storage density (W) of 6.05 J/cm3 with a high energy efficiency (η) of 85.9% is implemented. Within the broad temperature range from 20 to 140 °C, the numerical fluctuations of energy storage characteristics can be maintained at a relatively stable level (ΔWrec ≈ 3.5%, Δη ≈ 2.8%). As for the charging-discharging performances, this component possesses a fast discharging speed (t0.90 ≈ 51 ns) and remarkable temperature stability (the variations are smaller than 3.5%). Additionally, the internal mechanisms of outstanding energy storage properties can be confirmed via crystal structures and domain structures, the content of oxygen vacancies, dielectric and impedance spectra, and phase simulation. Hence, the combination of outstanding energy storage with remarkable thermal stability can be fulfilled in one ceramic system according to this discovery, providing a research thought of developing the materials for dielectric capacitors.

High‐Entropy Design Toward Ultrahigh Energy Storage Density Under Moderate Electric Field in Bulk Lead‐Free Ceramics

AbstractElectrostatic capacitors with ultrahigh energy‐storage density are crucial for the miniaturization of pulsed power devices. A long‐standing challenge is developing dielectric materials that achieve ultrahigh recoverable energy density Wrec ≥ 10 J cm−3 under moderate electric fields (30 ≤ E ≤ 50 kV mm−1). Herein, a specific high‐entropy strategy is proposed to modulate the phase structure and interfacial polarization of medium‐entropy base materials using linear dielectrics. This strategy ensures a sufficient polar phase and a high enough electric field for complete polarization, thereby achieving ultrahigh Wrec by enhancing polarization strength. The validity of this strategy is demonstrated in the (Na0.282Bi0.282Ba0.036Sr0.28Nd0.08)TiO3‐xCa0.7Bi0.2TiO3 (NBBSNT‐xCBT) (x = 0–0.15) system. The CBT‐modulated samples exhibit a polyphase structure of R3c, P4bm, and Pm‐3m with reduced remnant polarization (Pr). Additionally, the addition of CBT effectively suppresses interfacial polarization, enhancing the maximum polarization (Pmax). These factors significantly improve the value of ∆P = Pmax − Pr. As a result, an ultrahigh Wrec of 10.5 J cm−3 with a high‐efficiency η of 80.3% is obtained in the x = 0.1 sample under a moderate electric field of 45 kV mm−1 for the first time. This work paves the way for achieving superior energy‐storage performance under moderate electric fields.

Ultra-high energy storage density in PBSLZS antiferroelectric thick film ceramics

Superior recoverable energy density (Wrec) and efficiency (η) are crucial parameters for capacitors used in pulse-power devices. Here, we achieved an ultrahigh Wrec and high η in (Pb0.95-xBa0.02SrxLa0.02)(Zr0.65Sn0.35)O3 (PBSLZS) antiferroelectric thick film ceramics. All ceramics exhibit an orthorhombic structure, and the forward switching field increases with the increase of Sr2+ ionic content. The PBSLZS (x = 0.03) ceramics exhibit maximum value of total energy density (Wtot) and Wrec of 14.9 J/cm3 and 12.9 J/cm3, respectively, along with a high η of 86.6% at 570 kV/cm. Furthermore, we investigated the impact of multi-field coupling, i.e., the electric field and temperature, on the energy storage performance. An electric field (E) versus temperature (T) phase diagram was also obtained. The outstanding energy storage performance observed in PBSLZS ceramics demonstrates the potential for energy storage capacitors.

Ultrahigh energy storage performance in BNT-based binary ceramic via relaxor design and grain engineering

Dielectric capacitors attract much attention for advanced electronic systems owing to their ultra-fast discharge rate and high power density. However, the low energy storage density (Wrec) and efficiency (η) severely limit their applications. Herein, Bi0.5Na0.5TiO3-K0.5Na0.5NbO3 binary ceramic is developed to obtain excellent energy storage performance with strong relaxor behavior, together with large polarization and distorted lattice calculated by first-principles calculations. The atomic-scale local structure analysis of 0.75Bi0.5Na0.5TiO3–0.25K0.5Na0.5NbO3 ceramic reveals distorted polarization distribution and small polar nanoregion related with the enhanced relaxation and low hysteresis. Finite element analysis demonstrates ultrafine grain and increased grain boundary density following hot-pressing sintering are crucial factors in significantly enhancing the breakdown strength (Eb). As a result, ultrahigh Wrec of 12.39 J/cm3 and η of 87.1 % are achieved at a superhigh Eb of 713 kV/cm. Encouragingly, excellent performance of temperature, frequency and fatigue stability at 400 kV/cm are obtained, and high power density of ∼ 306 MW/cm3 as well as fast discharge speed of ∼ 23.3 ns are also realized. This work proposes a simple binary design with strong relaxor behavior, and highlights the potential of grain engineering to achieve outstanding energy storage performance with great stability and excellent charge-discharge property for pulse power devices.

High energy storage performance under low electric fields and remarkable dielectric temperature stability in (Na0.5Bi0.5)TiO3-based lead-free ceramics

Lead-free ceramic capacitors with superior energy storage properties and dielectric temperature stability are urgent needs for pulsed power devices. However, the risk of high voltage suppresses the improvement of comprehensive performance. Thus, a novel (1-x)(0.55Na0.5Bi0.5TiO3-0.45Ba0.85Ca0.15Zr0.1Ti0.9O3)-xBi(Mg2/3Ta1/3)O3 (NBBCZT-xBMT) ceramics were successfully synthesized to address the above concerns. The addition of BMT is beneficial to maintaining high polarization strength, improving the breakdown strength and optimizing relaxor behavior. As a result, the optimum component exhibits excellent energy storage capability (Wrec = 3.05 J/cm3, η = 94.3 %) at 190 kV/cm and dielectric temperature stability (TCC ≤ ±10 % from 33 to 348 °C, tanδ ≤ 0.01 from 50 to 389 °C). Moreover, the corresponding sample maintains a variation of Wrec less than 6.7 % and η less than 1.6 % at 20–140 °C and 1–100 Hz. These results provide a novel candidate for high-performance ceramic capacitors under low electric fields.

Regulating the switching electric field and energy-storage performance in antiferroelectric ceramics via heterogeneous laminated engineering

Antiferroelectric (AFE) ceramics with near-zero remanent polarization originating from unique electric field-induced antiferroelectric-ferroelectric phase transition are of great importance for the application in the energy-storage devices. However, achieving the most widely optimized switching electric field and energy-storage performance of antiferroelectric ceramics has predominantly relied on A/B-site ion doping strategies, often accomplished through a series of experimental and analytical works. In this context, we propose a novel strategy of heterogeneous laminated engineering as a substitute for A/B-site ion doping. This approach allows for a more intuitive regulation of the switching electric field and energy-storage performance in antiferroelectric ceramics without the need for complicated workload. Namely, the ferroelectric Pb0.99(Nb0.9Ta0.1)0.2(Zr0.9Sn0.1)0.8O3 (PNTZS) and antiferroelectric (Pb0.875La0.05Sr0.05) (Zr0.7Sn0.3)O3 (PLSZS) were layer-by-layer laminated using a tape-casting technique. All heterogeneous laminated ceramics exhibit antiferroelectric characteristics, and the magnitude of the switching electric field can be controlled by regulating the ratio between PNTZS and PLSZS. Furthermore, the finite element simulation revealed differences in the local electric fields between PNTZS and PLSZS in heterogeneous laminated ceramics, resulting in a win-win situation for both polarization and the breakdown strength. A large recoverable energy density of 11.2 J cm−3 with ultrahigh energy efficiency of 94.2 % can be obtained under 56 kV mm−1. Moreover, the energy storage performance shows no obvious deterioration in a broad frequency range (1–100 Hz) and temperature range (25–120 °C). Particularly, the outstanding discharge properties with a large discharge energy density of 7.1 J cm−3 and a high power density of 263.7 MW cm−3 show great potential for energy-storage applications. To conclude, a new strategy is opened up herein for designing antiferroelectric energy storage materials, showing the great application potential in the pulse power devices.

Local Isomeric Polar Nanoclusters Enabled Superior Capacitive Energy Storage Under Moderate Fields in NaNbO3-Based Lead-Free Ceramics.

The high-field energy-storage performance of dielectric capacitors has been significantly improved in recent years, yet the high voltage risks of device failure and large cost of insulation technology increase the demand for high-performance dielectric capacitors at finite electric fields. Herein, a unique superparaelectric state filled with polar nanoclusters with various local symmetries for lead-free relaxor ferroelectric capacitors is subtly designed through a simple chemical modification method, successfully realizing a collaborative improvement of polarization hysteresis, maximum polarization, and polarization saturation at moderate electric fields of 20-30kVmm-1. Therefore, a giant recoverable energy density of ≈5.0Jcm-3 and a high efficiency of ≈82.1% are simultaneously achieved at 30kVmm-1 in (0.9-x)NaNbO3-0.1BaTiO3-xBiFeO3 lead-free ceramics, showing a breakthrough progress in moderate-field comprehensive energy-storage performances. Moreover, superior charge-discharge performances of high-power density ≈182MWcm-3, high discharge energy density ≈4.3Jcm-3 and ultra-short discharge time <70ns as well as excellent temperature stability demonstrate great application potentials for dielectric energy-storage capacitors in pulsed power devices. This work provides an effective and paradigmatic strategy for developing novel lead-free dielectrics with high energy-storage performance under finite electric fields.

Achieving ultrahigh energy storage performance of PBLZST-based antiferroelectric composite ceramics via interfacial polarization engineering

Antiferroelectric (AFE) ceramics can be used in pulse power devices for high power density and fast discharge. Composites are recognized as an effective strategy to combine the benefits of different materials but suffer from interfacial mismatch and interfacial polarization. In this work, a combination of high-breakdown Pb0.94La0.04(Zr0.99-xSnxTi0.01)O3 (PLZST) with high-efficiency Pb0.8925Ba0.04La0.045(Zr0.65Sn0.3Ti0.05)O3 (PBLZST) is explored to enhance energy storage performance. Via adjusting Sn content in PLZST, the difference in lattice and dielectric properties between two phases are reduced, decreasing interfacial polarization. The breakdown strength of PBLZST-PLZST is boosted from 285 kV cm−1 to 345 kV cm−1, with maximum polarization strength decreasing from 44 μC cm−2 to 36 μC cm−2. An recoverable energy density (Wre ∼ 7.152 J cm−3) and discharged efficiency (η ∼ 90.5%) has been achieved in Pb0.8925Ba0.04La0.045(Zr0.65Sn0.3Ti0.05)O3-Pb0.94La0.04(Zr0.69Sn0.3Ti0.01)O3 (x = 0.3) composite ceramics. These findings highlight the potential of interfacial polarization engineering for developing composite ceramics with high-energy storage performance.

Ceramic-Based Dielectric Materials for Energy Storage Capacitor Applications.

Materials offering high energy density are currently desired to meet the increasing demand for energy storage applications, such as pulsed power devices, electric vehicles, high-frequency inverters, and so on. Particularly, ceramic-based dielectric materials have received significant attention for energy storage capacitor applications due to their outstanding properties of high power density, fast charge-discharge capabilities, and excellent temperature stability relative to batteries, electrochemical capacitors, and dielectric polymers. In this paper, we present fundamental concepts for energy storage in dielectrics, key parameters, and influence factors to enhance the energy storage performance, and we also summarize the recent progress of dielectrics, such as bulk ceramics (linear dielectrics, ferroelectrics, relaxor ferroelectrics, and anti-ferroelectrics), ceramic films, and multilayer ceramic capacitors. In addition, various strategies, such as chemical modification, grain refinement/microstructure, defect engineering, phase, local structure, domain evolution, layer thickness, stability, and electrical homogeneity, are focused on the structure-property relationship on the multiscale, which has been thoroughly addressed. Moreover, this review addresses the challenges and opportunities for future dielectric materials in energy storage capacitor applications. Overall, this review provides readers with a deeper understanding of the chemical composition, physical properties, and energy storage performance in this field of energy storage ceramic materials.

Greatly improved energy storage density of SrO2–BaO2–Nb2O5–SiO2–Al2O3–B2O3 glass ceramics by various amount CeO2 doping

Glass ceramic dielectric materials with high power density and high energy density have important application value in the miniaturization and integration of lightweight pulse power devices. In this work, SrO2–BaO2–Nb2O5–SiO2–Al2O3–B2O3 glass ceramics doped with various contents of CeO2 were prepared via high-temperature melting combined with temperature-controlled crystallization process. Results showed that CeO2 doping increased the content of Ba0.27Sr0.75Nb2O5.78 tungsten bronze phase precipitate from the glass matrix in glass ceramics (from 55.7% to 82.2%), thereby increasing dielectric constant of SrO2–BaO2–Nb2O5–SiO2–Al2O3–B2O3 glass ceramics (from 66.5 to 101.9). Besides that, CeO2-doped ceramics exhibited excellent temperature stability and low loss (below 0.015). The highest breakdown strength (1590 kV/cm) and energy density (12.88 J/cm3) were achieved in the ceramic with a CeO2 doping concentration of 3.0 mol.%, being 3.03 times higher than those in undoped glass ceramic. The increase in energy density of the ceramics was attributed to moderate CeO2 doping concentration that improved the crystallinity (from 83.8% to 89.8%) and reduced the interfacial activation energy of the glass ceramics.

Bio-inspired pulsed power switch under shock wave

The spark gap switch is a crucial component in the primary energy drive system for large pulse power devices. The switch electrodes are composed of high-density artificial graphite, possessing excellent erosion resistance. However, insufficient mechanical strength in the graphite electrodes makes them especially susceptible to mechanical damage under the enormous impact force caused by the increasing arc current, which seriously affects the reliability and service life of the switch. The distribution of the shock wave overpressure on the graphite electrode surface is deduced and calculated, and the refraction and reflection process of the shock wave from the air to the graphite interface is analyzed based on the Huygens–Fresnel principle. Furthermore, the doubling of refracted shock wave intensity into the graphite electrode is a preliminary characterization. The propagation process of stress wave after the shock wave enters the electrode is investigated by establishing two conventional graphite electrode structure models, namely T-shape and reverse T-shape, which reveal that severe stress concentration occurs in both structures. Drawing inspiration from the physiological structure of the woodpecker’s head, renowned for its exceptional impact resistance, the macroscopic geometry of the graphite electrode and the assembly structure of the switch have been bionically designed. The simulation results demonstrate that, in comparison to the conventional electrode structure, the bionic electrode structure eliminates stress concentration at the bolt end and electrode corner, while significantly reducing maximum equivalent stress and the degree of the stress concentration on the bottom surface of the electrode. These features contribute to the enhancement of the current capacity and reliability of the spark gap switch.

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.

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.

Reliability of Bioreactance and Pulse-Power Analysis in Measuring Cardiac Index During Open Abdominal Aortic Surgery

To investigate the accuracy, precision, and trending ability of noninvasive bioreactance-based Starling SV and the mini invasive pulse-power device LiDCOrapid as compared to thermodilution cardiac output (TDCO) as measured by pulmonary artery catheter when assessing cardiac index (CIx) in the setting of elective open abdominal aortic (AA) surgery. A prospective method-comparison study. Oulu University Hospital, Finland. Forty patients undergoing elective open abdominal aortic surgery. Intraoperative CI measurements were obtained simultaneously with TDCO and the study monitors, resulting in 627 measurement pairs with Starling SV and 497 with LiDCOrapid. The Bland-Altman method was used to investigate the agreement among the devices, and four-quadrant plots with error grids were used to assess trending ability. The agreement between TDCO and Starling SV was associated with a bias of 0.18 L/min/m2 (95% confidence interval [CI] = 0.13 to 0.23), wide limits of agreement (LOA = -1.12 to 1.47 L/min/m2), and a percentage error (PE) of 63.7 (95% CI = 52.4-71.0). The agreement between TDCO and LiDCOrapid was associated with a bias of -0.15 L/min/m2 (95% CI = -0.21 to -0.09), wide LOA (-1.56 to 1.37), and a PE of 68.7 (95% CI = 54.9-79.6). The trending ability of neither device was sufficient. The CI measurements achieved with Starling SV and LiDCOrapid were not interchangeable with TDCO, and the ability to track changes in CI was poor. These results do not support the use of either study device in monitoring CI during open AA surgery.

Enhanced energy storage performance with improved phase transition field in PBLZST AFE ceramics by the SPS method

PLZST-based antiferroelectric dielectric capacitors are the most advantageous materials in pulse power devices. However, the PbO volatilization, low recoverable energy density and efficiency (Wrec and η) hinder the large-scale development and application. An effective strategy was proposed by modifying the antiferroelectric with a linear dielectric material Ca(Zr,Ti)O3 via spark-plasma-sintering (SPS). This research achieved a remarkable Wrec of 5.54 J/cm3, exceptionally high recoverable energy storage intensity (ρ) of 20.52 × 10−3 J/kV∙cm−2 and η of 83%. The enhancement in Wrec and ρ resulted from the enhanced phase-transition-field by the decreased tolerance factor and increased electronegativity difference, the grains refinement and stoichiometric ratio accuracy by SPS. The increase of η was due to the non-ferroelectrically Ca2+ on the A-site and the improved insulation by SPS. Moreover, the rapid and low temperature sintering helped inhibit lead volatilization and increased mechanical hardness (HV > 7 GPa). Our work demonstrates that PBLZST-based ceramics prepared by SPS can be exploited for enhanced energy-storage performance under a low voltage in an environmentally-friendly way.