Variation Of Energy Density Research Articles

Multiphase Engineered BNT-Based Ceramics with Simultaneous High Polarization and Superior Breakdown Strength for Energy Storage Applications.

Dielectric ceramics are crucial for high-temperature, pulse-power energy storage applications. However, the mutual restriction between the polarization and breakdown strength has been a significant challenge. Here, multiphase engineering controlled by the two-step sintering heating rate is adopted to simultaneously obtain a high polarization and breakdown strength in 0.8(0.95Bi0.5Na0.5TiO3-0.05SrZrO3)-0.2NaNbO3 (BNTSZNN) ceramic systems. The coexistence of tetragonal (T) and rhombohedral (R) phases benefits the temperature stability of BNTSZNN ceramics. Increasing the heating rate during sintering reduces the diffusion of SrZrO3 and NaNbO3 into Bi0.5Na0.5TiO3, which results in a high proportion of the R phase and a finer grain size. The overall polarization is enhanced by increasing the proportion of the high-polarization R phase, which is demonstrated using a first-principles method. Meanwhile, the finer grain size enhances the breakdown strength. Following this design philosophy, an ultrahigh Wdis of 5.55 J/cm3 and η above 85% is achieved in BNTSZNN ceramics as prepared with a fast heating rate of 60 °C/min given a simultaneously high polarization of 43 μC/cm2 and high breakdown strength of 350 kV/cm. Variations in the discharge energy density from room temperature to 160 °C are less than 10%. Additionally, such BNTSZNN ceramics exhibit an ultrafast discharge speed with τ0.9 at approximately 60 ns, which shows great potential in pulse-power system applications.

Langmuir-Blodgett deposited Na3V2(PO4)3-MnO2 nanocomposite thin film electrodes for hybrid energy storage application

This article deals with the Langmuir-Blodgett deposition of NASICON type Na3V2(PO4)3 (NVP) -MnO2 nanocomposite thin-film for the hybrid energy storage application. The nanocomposite electrode with various NVP: MnO2 ratio was developed and their physiochemical properties were examined with advanced characterisation techniques. The aqueous half-cell was made using the developed nanocomposite electrodes, to study their energy storing behaviour by CV and GCD analysis. In comparison, the 3:1 ratio of NVP-MnO2 (NM3) exhibits a higher specific capacity with good cyclic stability and rate capability. The higher MnO2 concentration leads to the dominance of pseudo capacitance behaviour over the battery like reaction, resulted in the variation of energy density and power density between 39 and 18 Wh/Kg and 3479–4450 W/Kg.

Load adaptation through bone remodeling: a mechanobiological model coupled with the finite element method.

This work proposes a novel tissue-scale mechanobiological model of bone remodeling to study bone's adaptation to distinct loading conditions. The devised algorithm describes the mechanosensitivity of bone and its impact on bone cells' functioning through distinct signaling factors. In this study, remodeling is mechanically ruled by variations of the strain energy density (SED) of bone, which is determined by performing a linear elastostatic analysis combined with the finite element method. Depending on the SED levels and on a set of biological signaling factors ([Formula: see text] parameters), osteoclasts and osteoblasts can be mechanically triggered. To reproduce this phenomenon, this work proposes a new set of [Formula: see text] parameters. The combined response of osteoclasts and osteoblasts will then affect bone's apparent density, which is correlated with other mechanical properties of bone, through a phenomenological law. Thus, this novel model proposes a constant interplay between the mechanical and biological components of the process. The spatiotemporal simulation used to validate this new approach is a benchmark example composed by two distinct phases: (1) pre-orientation and (2) load adaptation. On both of them, bone is able to adapt its morphology according to the loading condition, achieving the required trabecular distribution to withstand the applied loads. Moreover, the equilibrium morphology reflects the orientation of the load. These preliminary results support the new approach proposed in this study.

Associations between dietary patterns and the incidence of total and fatal cardiovascular disease and all-cause mortality in 116,806 individuals from the UK Biobank: a prospective cohort study

BackgroundTraditionally, studies investigating diet and health associations have focused on single nutrients. However, key nutrients co-exist in many common foods, and studies focusing solely on individual nutrients may obscure their combined effects on cardiovascular disease (CVD) and all-cause mortality. We aimed to identify food-based dietary patterns which operate through excess energy intake and explain high variability in energy density, free sugars, saturated fat, and fiber intakes and to investigate their association with total and fatal CVD and all-cause mortality.MethodsDetailed dietary data was collected using a 24-h online dietary assessment on two or more occasions (n = 116,806). We used reduced rank regression to derive dietary patterns explaining the maximum variance. Multivariable Cox-proportional hazards models were used to investigate prospective associations with all-cause mortality and fatal and non-fatal CVD.ResultsOver an average of 4.9 years of follow-up, 4245 cases of total CVD, 838 cases of fatal CVD, and 3629 cases of all-cause mortality occurred. Two dietary patterns were retained that jointly explained 63% of variation in energy density, free sugars, saturated fat, and fiber intakes in total. The main dietary pattern was characterized by high intakes of chocolate and confectionery, butter and low-fiber bread, and low intakes of fresh fruit and vegetables. There was a positive linear association between the dietary pattern and total CVD [hazard ratio (HR) per z-score 1.07, 95% confidence interval (CI) 1.04–1.09; HRtotal CVD 1.40, 95% CI 1.31–1.50, and HRall-cause mortality 1.37, 95% CI 1.27–1.47 in highest quintile]. A second dietary pattern was characterized by a higher intakes of sugar-sweetened beverages, fruit juice, and table sugar/preserves. There was a non-linear association with total CVD risk and all-cause mortality, with increased risk in the highest quintile [HRtotal CVD 1.14, 95% CI 1.07–1.22; HRall-cause mortality 1.11, 95% CI 1.03–1.19].ConclusionsWe identified dietary patterns which are associated with increased risk of CVD and all-cause mortality. These results help identify specific foods and beverages which are major contributors to unhealthy dietary patterns and provide evidence to underpin food-based dietary advice to reduce health risks.

Smart power system of biocompatible and flexible micro-supercapacitor

Flexible micro-supercapacitor (MSC) is an ideal energy storage device for flexible and small-scale electronics, specifically some human health sensors, because of its flexibility, long working life, high power density, and high charge and discharge rate. In this work, a smart power system of MSC is developed. First, utilizing ink-jet printing and electrochemical deposition, flexible MSC is fabricated on the biocompatible substrate of a modified silk protein film, making the power system suitable for implantable devices. Second, aiming at the common drawbacks of small energy density and large voltage variation of MSC, a wireless charging component and a wireless inductor–capacitor (LC) voltage sensor are integrated with the MSC unit. Using pulse charging mode, charging and voltage detection can be performed at the same time. The LC voltage sensor, using varactor diodes to realize voltage capacitance mapping, does not need extra ICs or consume any energy. Such a system has great application potential as the energy supply part of small devices implanted in the human body.

Effects of spatial energy distribution-induced porosity on mechanical properties of laser powder bed fusion 316L stainless steel

Laser powder bed fusion (LPBF) additive manufacturing (AM) offers a variety of advantages over traditional manufacturing, however its usefulness for manufacturing of high-performance components is currently hampered by internal defects (porosity) created during the LPBF process that have an unknown impact on global mechanical performance. By inducing porosity distributions through variations in print energy density and inspecting the resulting tensile samples using computed tomography, nearly 50,000 pores across 75 samples were identified. Porosity characteristics were quantitatively extracted from inspection data and compared with mechanical properties to understand the strength of relationships between porosity and global tensile performance. Useful porosity characteristics were identified for prediction of part performance. Results indicate that ductility and strain at ultimate tensile strength are the global tensile properties most significantly impacted by porosity and can be predicted with reasonable accuracy using simple porosity shape descriptors such as volume, diameter, and surface area. Moreover, it was found that the largest pores influenced behavior most significantly. Specifically, pores in excess of 125 µm in diameter were found to be a sufficient threshold for property estimation. These results establish an initial understanding of the complex defect-performance relationship in AM 316L stainless steel and can be leveraged to develop certification standards and improve confidence in part quality and reliability for the broader set of engineering alloys.

Neutralization of radionuclides

Three cases are reviewed of radioactive material with anomalous decay after ultrasound irradiation. In the pure element thorium-228 in distilled water, the radioactivity decreased faster after cavitation than the natural decay. The more complex molecule of Nickel Nitrate, made of radioactive nickel-63, in solution of nitric acid and distilled water was investigated before and after ultrasound irradiation. The X-rays produced by Bremsstrahlung of the electrons from the beta decay of Ni-63 were recorded and a 13% decrease of intensity was measured after 100 s of sonication. A decrease of nickel and an increase of other elements was detected by mass spectrometry in the sonicated sample. The Cobalt-57 decay was investigated by detecting the gamma and X-ray intensity from the Iron-57 resulting after its beta emission. In this third case too, an anomalous decay was observed after sonication. These three cases of anomalous behavior can be explained at the light of the Deformed Space–Time theory. It assumes that a suitable sudden variation of energy density can induce a local deformation of space–time, thus violating the Local Lorentz Invariance. This variation can be created by the ultrasounds in the matter, thus, allowing reactions that cannot occur in a flat (Minkowskian) space–time. The “neutralization” of a radionuclide occurs when it undergoes a DST transformation changing the radionuclide into non-radioactive nuclides.

Magnetic Energy Balance in the Quiet Sun on Supergranular Spatial and Temporal Scales

Abstract Small-scale magnetic fields are ubiquitous in the quiet solar photosphere and may store and transfer huge amounts of energy to the upper atmospheric layers. For this reason, it is fundamental to constrain the energetics of the quiet Sun. By taking advantage of a 24 hr long magnetogram time series acquired by the Hinode mission without interruption, we computed, for the first time, the average rate of change of magnetic energy density on supergranular spatial and temporal scales. We found that the regions where this quantity is positive correspond with the longest magnetic field decorrelation times, with the latter being consistent with the timescales of magnetic energy density variation. This suggests that, on average, the energy provided by photospheric electric and magnetic fields and current density is effective in sustaining the magnetic fields in the network.

Giant energy density and high efficiency achieved in silver niobate-based lead-free antiferroelectric ceramic capacitors via domain engineering

Dielectric materials have drawn increasing attention due to their high power density and fast charge-discharge speed. Although satisfactory energy storage performance has been achieved in lead-based ceramics, the exploration of suitable lead-free substitutions is highly desired since the rising environmental concerns caused by lead-based compounds. Herein, we demonstrate that a giant recoverable energy density of 7.01 J cm−3 together with high energy efficiency under 476 kV cm−1, as well as impressive frequency stability (maximum variation of recoverable energy density < ±3% at 1 − 100 Hz) and thermal stability (maximum variation < ±10% over 25−120 °C) under 320 kV cm−1, can be obtained in Lanthanum (La)-modified AgNbO3 ceramics. It is revealed that the long-range antiferroelectric order in AgNbO3 is interrupted by the incorporation of La, resulting in the transformation of micron-scale antiferroelectric domains into antiferroelectric nanodomains with concurrently improved energy density and efficiency. Additionally, the introduction of La content greatly suppresses the ferrielectricity of AgNbO3 and enhances the dielectric breakdown strength up to 494 kV cm−1 versus 178 kV cm−1 for the pure AgNbO3 ceramics. These results not only reveal the high potential of La-modified AgNbO3 ceramics for energy storage applications but also open up a feasible approach of domain engineering to develop new lead-free energy-storage dielectric materials.

Atmospheric Precipitation and Anomalous Upper Mantle in Relation to Intraplate Seismicity in Norway

AbstractTwo enigmatic regions of high intraplate seismicity in Norway (Western Norway and the Nordland area) show a temporal correlation between the number of earthquakes within the upper crystalline crust and intensity of rain and snowmelt at the Earth's surface. This correlation is obvious in the Nordland area where detailed and reliable data on seismicity are available, whereas the correlation is weaker in Western Norway where detailed data on seismicity are missing. Moreover, these discrete zones of high seismic activity coincide spatially with prominent, low‐velocity, and, most likely, thermally anomalous zones in the upper mantle. We propose that in addition to other causes, the high seismicity may be controlled by the anomalous upper mantle, along with topographically induced gravitational potential energy and crustal density variations. Precipitation‐induced, seasonal increases in pore‐fluid pressure within the fractured crystalline bedrock and changes in water loads may modulate the tectonically controlled seismicity.

First Lidar Observations of Quasi‐Biennial Oscillation‐Induced Interannual Variations of Gravity Wave Potential Energy Density at McMurdo via a Modulation of the Antarctic Polar Vortex

AbstractThis work presents the first lidar observations of a Quasi‐Biennial Oscillation (QBO) in the interannual variations of stratospheric gravity wave potential energy density (Epm in 30–50 km) at McMurdo (77.84°S, 166.67°E), Antarctica. This paper also reports the first identification of QBO signals in the distance between McMurdo and the polar vortex edge. Midwinter stratospheric gravity wave activity is stronger during the QBO easterly phase when the June polar vortex expands and the polar night jet shifts equatorward. During the QBO westerly phase, gravity wave activity is weaker when the polar vortex contracts and the polar night jet moves poleward. Nine years of lidar data (2011–2019) exhibit the mean Epm winter maxima being ~43% higher during QBO easterly than westerly. The June polar vortex edge at 45 km altitude moves equatorward/poleward during QBO easterly/westerly phases with ~8° latitude differences (39.7°S vs. 47.7°S) as revealed in 21 years of MERRA‐2 data (1999–2019). We hypothesize that an equatorward shifted polar vortex corresponds to less critical level filtering of gravity waves and thus higher Epm at McMurdo. The critical level filtering is characterized by wind rotation angle (WRA), and we find a linear correlation between the WRA and Epm interannual variations. The results suggest that the QBO is likely controlling the interannual variations of the Epm winter maxima over McMurdo via the critical level filtering. This observationally based study lays the groundwork for a rigorous numerical study that will provide robust statistics to better understand the mechanisms that link the tropical QBO to extratropical waves.

Wake transition for surface mounted rectangular cylinder due to incoming shear flow

ABSTRACT Three-dimensional unsteady wake characteristics have been investigated numerically in flow past surface mounted finite-height rectangular cylinder using Open Source Field Operation and Manipulation. Effect of impinging shear (shear intensity, K) on transitional characteristics of wake flow has been studied using iso-Q surfaces for Reynolds number (Re) in the range from 150 to 250. Various flow regimes, such as steady flow, symmetric and asymmetric modes of vortex shedding have been identified based on the values of Re and K for different side ratios (SR) of the cylinder. Unsteady wake oscillations have been analyzed using time signal of transverse velocity component in the wake. These signals have been decomposed into different component signals using Hilbert-Huang transformation (HHT). Variation of frequency and energy density with time of the decomposed signals has been presented in the form of Hilbert spectra. Effects of Re, SR and K on wake oscillation frequency have been illustrated in the form of marginal spectra. Time-delay reconstructions and Poincare sections have been examined to study periodic and aperiodic nature of the wake flow. Non-stationarity associated with the wake fluctuation is quantified in terms of degree of stationarity. Symmetric and asymmetric modes have been confirmed using singular value decomposition of the vorticity field and presented using dynamic modes. Growth rate and frequency of the modes corresponding to symmetric shedding are found to be lower than those for asymmetric shedding. In addition, variation in mean drag coefficient has been reported with change in Re and K for each value of SR.

Oxyntomodulin and Glicentin May Predict the Effect of Bariatric Surgery on Food Preferences and Weight Loss

Alterations in several gastrointestinal hormones are implicated in the postoperative suppression of food intake leading to weight loss after Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG). The aim was to evaluate changes in responses of gastrointestinal hormones after RYGB and SG and the associations of these changes with weight loss, energy intake, and food preferences. Forty-two subjects with severe obesity were included (32 RYGB; 10 SG). Postprandial responses of glicentin, oxyntomodulin, glucagon-like peptide-1 (GLP-1), peptide YY (PYY), and ghrelin were measured before and 6 months after surgery. Energy intake and energy density were assessed before and 6 months after surgery using a buffet meal test and weight loss was assessed 18 months after surgery. Postprandial concentrations of glicentin, oxyntomodulin, GLP-1, and ghrelin differed between RYGB and SG (all P ≤ .02). Enhanced responses of glicentin and oxyntomodulin predicted a greater weight loss (both P < .01) and were associated with a larger decrease in energy density (P ≤ .04). No associations were found for GLP-1, PYY, and ghrelin, and changes were not associated with changes in energy intake. When combing all hormones, 60%, 19%, and 33% of the variations in weight loss, energy intake, and energy density, respectively, could be explained. Postprandial responses of gastrointestinal hormones differed between RYGB and SG. Enhanced responses of glicentin and oxyntomodulin predicted a better weight loss and were associated with a decreased preference for energy-dense foods. Replication of these results could imply an opportunity to identify patients in need of additional support after surgical treatments of obesity.

Effects of dielectric thickness on energy storage properties of 0.87BaTiO3-0.13Bi(Zn2/3(Nb0.85Ta0.15)1/3)O3 multilayer ceramic capacitors

Multilayer Ceramic Capacitors (MLCCs) for energy storage applications require a large discharge energy density and high discharge/charge efficiency. Here, 0.87BaTiO3-0.13Bi(Zn2/3(Nb0.85Ta0.15)1/3)O3 (BTBZNT) powders were synthesized via solid-state reactions, and MLCCs with sub-micron grains were fabricated using a two-step sintering method. The BTBZNT MLCCs, which are well-defined relaxor ferroelectrics, possessed relatively high permittivity, dielectric sublinearity, and negligible hysteresis. An AC breakdown strength (BDS) enhancement from 511 to 1047 kV/cm was obtained as the dielectric thickness (D) decreased from 26 to 5 μm. The strong correlation between BDS and D, described asBDS∝D−0.368, agreed well with the general macroscopic theory of thermal breakdown in insulators. The enhanced BDS afforded the BTBZNT MLCCs (D∼9 μm) with excellent energy storage properties with a maximum discharge energy density of 10.5 J/cm3 and discharge/charge efficiency of 93.7% under a maximum electric field of 1000 kV/cm. The MLCCs also exhibited excellent thermal stability with discharge energy density variation <±5% over a wide temperature range of −50 to 175 °C under an electric field of 400 kV/cm. These remarkable performances make BTBZNT MLCCs promising for energy storage applications.

Breakdown Field Strength Variations and Energy Density Limits of Nanoparticle Composite Materials

In response to the growing demand for renewable energy storage technologies, current research into nanoparticle (NP) composite materials seeks to push the boundaries of energy density for solid-state capacitive energy storage. To understand the limits of these composites, it is important to understand the electric field patterns and breakdown events that prevent such devices from storing more energy per unit volume. To this end, a novel breakdown path detection algorithm is designed to mimic breakdown events by using the internal electric fields to determine the breakdown voltage of simulated composite materials. This breakdown path detection model is used to calculate the energy density for over 1200 different geometries for BaTiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> NPs embedded in a P(VDFHFP) host matrix. These simulations reveal a large normalized variation in the volumetric energy density of up to 54%. Furthermore, these P(VDF-HFP)/BaTiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> composites are found to have only a modest improvement in energy density of 1.08× compared to the pure P(VDF-HFP) host; however, alternative hypothetical NP compositions composed of SrTiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> , SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , and HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> NP inclusions showed increases in energy density of up to 5.64× for SrTiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> (volume fraction of 0.48), 8.87× for SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> (volume fraction of 0.34), and 2.89× for HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> (volume fraction of 0.38).

Dielectric, ferroelectric and high energy storage behavior of (1–&lt;i&gt;x&lt;/i&gt;)K&lt;sub&gt;0.5&lt;/sub&gt;Na&lt;sub&gt;0.5&lt;/sub&gt;NbO&lt;sub&gt;3&lt;/sub&gt;–&lt;i&gt;x&lt;/i&gt;Bi(Mg&lt;sub&gt;0.5&lt;/sub&gt;Ti&lt;sub&gt;0.5&lt;/sub&gt;)O&lt;sub&gt;3&lt;/sub&gt; lead free relaxor ferroelectric ceramics

Lead-free dielectric ceramics with high energy-storage density and efficiency are ideal energy materials for sustainable development of the enery resource. In this paper, (1–&lt;i&gt;x&lt;/i&gt;)K&lt;sub&gt;0.5&lt;/sub&gt;Na&lt;sub&gt;0.5&lt;/sub&gt;NbO&lt;sub&gt;3&lt;/sub&gt;–&lt;i&gt;x&lt;/i&gt;Bi(Mg&lt;sub&gt;0.5&lt;/sub&gt;Ti&lt;sub&gt;0.5&lt;/sub&gt;)O&lt;sub&gt;3&lt;/sub&gt; ((1–&lt;i&gt;x&lt;/i&gt;)KNN-&lt;i&gt;x&lt;/i&gt;BMT, &lt;i&gt;x&lt;/i&gt; = 0.05, 0.10, 0.15, 0.20) lead-free relaxor ferroelectric ceramics are prepared by the traditional solid-state method. The effects of BMT on the phase structure, microstructure, dielectric properties and energy storage behavior of KNN based ceramics are studied. With the increase of BMT content, the crystal structures of (1–&lt;i&gt;x&lt;/i&gt;)KNN-&lt;i&gt;x&lt;/i&gt;BMT ceramics gradually change from orthorhombic to pseudo-cubic phase, and transform into cubic phase finally. The addition of BMT can suppress grain growth of the ceramics, resulting in the average grain size decreasing from 850 to 195 nm when &lt;i&gt;x&lt;/i&gt; increases from 0.05 to 0.20. Dielectric properties exhibit that the Curie temperature decreases with BMT content increasing, and dielectric peak at Curie temperature is broadened due to the addition of BMT. In addition, ferroelectric properties demonstrate that the addition of BMT reduces the remnant polarization (&lt;i&gt;P&lt;/i&gt;&lt;sub&gt;r&lt;/sub&gt;) and coercive field (&lt;i&gt;E&lt;/i&gt;&lt;sub&gt;c&lt;/sub&gt;) of the ceramics. The results indicate that (1–&lt;i&gt;x&lt;/i&gt;)KNN-&lt;i&gt;x&lt;/i&gt;BMT ceramics transform from ferroelectric to relaxor ferroelectric phase. Based on the calculation of hysteresis loop, the best energy storage performance is obtained at &lt;i&gt;x&lt;/i&gt; = 0.15, of which the recoverable energy storage density (&lt;i&gt;W&lt;/i&gt;&lt;sub&gt;rec&lt;/sub&gt;) and the energy storage efficiency (&lt;i&gt;η&lt;/i&gt;) are 2.25 J·cm&lt;sup&gt;–3&lt;/sup&gt; and 84% at its dielectric breakdown strength of 275 kV·cm&lt;sup&gt;–1&lt;/sup&gt;. Meanwhile, the ceramic with &lt;i&gt;x&lt;/i&gt; = 0.15 exhibits good stability in a frequency range of 1–50 Hz, with an energy density variation of less than 5%, and temperature stability in a range of 25–125 ℃ with change of less than 8%. Moreover, based on direct measurement, the energy storage density (&lt;i&gt;W&lt;/i&gt;&lt;sub&gt;dis&lt;/sub&gt;) of the ceramic with &lt;i&gt;x&lt;/i&gt; = 0.15 is 1.54 J·cm&lt;sup&gt;–3&lt;/sup&gt;, and the discharge time is only 88 ns. The research shows that (1–&lt;i&gt;x&lt;/i&gt;)KNN-&lt;i&gt;x&lt;/i&gt;BMT ceramics have a wide application prospect in the field of environmentally friendly capacitors with high energy storage density.

High energy density, high efficiency and excellent temperature stability of lead free Mn–doped BaTiO3–Bi(Mg1/2Zr1/2)O3 ceramics sintered in a reducing atmosphere

Dielectric ceramics capacitors are of great interest duo to the improved energy-storage performance and temperature stability. However, to lower the cost and achieve mass production, the co-sintering of dielectric ceramics with base metals (such as Ni, Cu) is a huge challenge, since the co-sintering requires a reducing atmosphere to prevent the oxidization of base metals. Here in this work, the multivalence element Mn is doped into a relaxor ferroelectric ceramic system, i.e. 0.85BaTiO3-0.15Bi(Mg1/2Zr1/2)O3 (BT-BMZ) ceramics through a conventional solid-state reaction method to realize the reducing atmosphere sintering. Effects of MnCO3 contents (0.05–0.25 wt%) on the energy-storage properties, temperature stabilities and electrical structures of the relaxor-ferroelectric BT-BMZ ceramics are investigated. The optimal energy-storage performance is found in 0.10 wt% MnCO3 doped BT-BMZ ceramics, with a high discharge energy density of 1.61 J/cm3 and an ultrahigh energy efficiency of 94.3% under the applied electric field of 230 kV/cm. Further, the variation in energy density is less than 15% over the temperature range from 25 to 140 °C under 120 kV/cm. Additionally, the impedance spectroscopy is used to analyze the insulation mechanism of these reducing-atmosphere-sintered Mn-doped BT-BMZ ceramics.

Mixed messages: Assessing interactions between portion-size and energy-density perceptions in different weight and sex groups

IntroductionFood portion size (PS) and energy density (ED) are the two primary determinants of total energy intake. While emerging neuroscientific data indicate judgments of PS and ED involve distinct brain regions, it is not understood how these judgements interact with each other to influence an individual's energy consumption. The present study investigated these cognitive interactions against body-mass-index (BMI) and sex. MethodsWe tested 70 participants (including 34 overweight individuals) for cognitive biases when judging PS and ED, using the Garner task paradigm. Participants were asked to discriminate PS and ED, following pre-determined cognitive rules. Reaction time and correctness of their responses were recorded and analysed against the testing conditions across sexes and BMI groups. ResultsWe detected a significant 3-way interaction between BMI, Task, and Condition (F(3, 67) = 4.1, p = 0.047, ƞ2 = 0.06). Post-hoc tests suggested that, in the PS task, both weight groups experienced the Garner Interference effect introduced by variations of ED. That is, when making judgments concerning PS, participants were unable to ignore information relating to ED. Results from the ED task differed across weight groups, with only the overweight group being susceptible to the Garner Interference introduced by variations of PS. Additionally, both Sex and BMI were significant factors moderating reaction time when judging PS. Significantly longer reaction time was observed in female versus male comparisons, and for overweight versus healthy-weight participants (p < 0.05). ConclusionOverall, the results confirmed cognitive interactions involving PS and ED, although these interactions were asymmetric across BMI groups. These findings provide new insights into the cognitive processes underpinning individual dietary decision-making, and are potentially important for developing targeted intervention strategies for effective management of unhealthy eating behaviour.

High energy storage properties of lead-free Mn-doped (1-x)AgNbO3-xBi0.5Na0.5TiO3 antiferroelectric ceramics

In this work, 0.2 wt.% Mn-doped (1-x)AgNbO3-xBi0.5Na0.5TiO3 (x = 0.00–0.04) ceramics were synthesized via solid state reaction method in flowing oxygen. The evolution of microstructure, phase transition and energy storage properties were investigated to evaluate the potential as high energy storage capacitors. Relaxor ferroelectric Bi0.5Na0.5TiO3 was introduced to stabilize the antiferroelectric state through modulating the M1-M2 phase transition. Enhanced energy storage performance was achieved for the 3 mol% Bi0.5Na0.5TiO3 doped AgNbO3 ceramic with high recoverable energy density of 3.4 J/cm3 and energy efficiency of 62% under an applied field of 220 kV/cm. The improved energy storage performance can be attributed to the stabilized antiferroelectricity and decreased electrical hysteresis ΔE. In addition, the ceramics also displayed excellent thermal stability with low energy density variation (<6%) over a wide temperature range of 20−80 °C. These results indicate that Mn-doped (1-x)AgNbO3-xBi0.5Na0.5TiO3 ceramics are highly efficient lead-free antiferroelectric materials for potential application in high energy storage capacitors.

Tailoring properties of (Bi0.51Na0.47)TiO3 based dielectrics for energy storage applications

Lead free dielectric ceramics of 0.65Bi0.51Na0.47Ti1-5x/4NbxO3- 0.35Ba(Ti0.7Zr0.3)O3 (BB35-100xNb, x = 0.00, 0.01, 0.02, 0.04 and 0.08) are fabricated by conventional solid-state sintering method for potential energy storage applications. Benefited from the coexistence of relaxor and antiferroelectric features, a high recoverable energy storage density of 3.2 J/cm3, together with high energy efficiency of 93%, is simultaneously achieved in bulk BB35-1Nb ceramic at the critical electric field of 280 kV/cm. The studied BB35-1Nb ceramic exhibits a wide temperature usage range of 20–160 °C with energy density variation below 3%, and excellent cycling reliability with both energy density and efficiency variations less than 4% over 106 cycles, together with its fast discharge time of ˜1.2 μs, making BB35-1Nb ceramic promising candidate for high-temperature, high power energy storage applications.