Polarization Energy Research Articles

Study of the magnetism of C-doped MgO based on first-principles calculations and the Ising model.

The electronic and magnetic properties of d0 dilute magnetic semiconductors formed by rock-salt structured magnesium oxide (MgO) doped with C are systematically studied based on first-principles calculations and the Ising model. It is shown that the electronic holes of p states are generated due to the impurity carbon replacing oxygen in MgO, and the magnetic moment of 2μB is introduced by each C impurity. The polarization energy and formation energy of C-doped MgO are calculated, and the magnetization energy of C-doped MgO is also calculated which is used to obtain the exchange constant between C impurities. By means of the Ising model, we simulated the magnetization and the susceptibility of the doped system with increasing temperature and obtained the Curie temperature of C-doped MgO.

First-principles prediction of ferroelectric Janus Si2XY (X/Y = S/Se/Te, X ≠ Y) monolayers with negative Poisson's ratios.

Nowadays, two-dimensional (2D) materials with Janus structures evoke much attention due to their unique mechanical and electronic properties. In this work, Janus Pma2-Si2XY (X/Y = S/Se/Te, X ≠ Y) ferroelectric monolayers are firstly proposed and systematically investigated by first-principles calculations. These monolayers exhibit remarkable mechanical properties, including small Young's modulus values, negative Poisson's ratios (NPRs) and large critical strains, reflecting their exceptional flexibility and stretchability. More strikingly, the novel structures of Si2STe and Si2SeTe also endow them with in-plane spontaneous polarization (Ps) and low energy barrier for phase transition, with Ps and energy barrier values being 1.632 × 10-10 C m-1 and 159 meV for Si2STe and 1.149 × 10-10 C m-1 and 196.6 meV for Si2SeTe. The ab initio molecular dynamics (AIMD) simulations reveal high Curie temperatures (Tc) for Si2STe and Si2SeTe, ranging between 1300 K and 1400 K. Additionally, Si2XY monolayers exhibit high anisotropic carrier mobility (∼103 cm2 V-1 s-1) and an extraordinary light absorption coefficient (∼105 cm-1). Our research not only broadens the family of 2D Janus ferroelectric materials, but also demonstrates their potential applications in nanomechanical, nanoelectronic and optoelectronic devices.

Achieving high energy storage density at low operating fields in lead hafnate-based novel perovskite solid solutions

Schematic diagram illustrating the concept, approaches and goal in the design and preparation of a new solid solution system (1 − x)PbHfO3–xAgNbO3, with enhanced maximum polarization and recoverable energy storage density at low operating fields.

Synergistically enhanced discharged energy density and efficiency achieved in designed polyetherimide-based composites via asymmetrical interlayer structure induced optimized interface effectiveness.

The continuous advancement in energy storage technologies necessitates the iteration of energy storage dielectrics urgently. However, the current state-of-the-art composite films fail to meet the application requirements of energy storage devices, which demand a combination of high discharged energy density (Ue), high energy storage efficiency (η), and excellent high-temperature performance. To address this challenge, we present an innovative interlayer composed of pure BN nanosheets in polyetherimide (PEI)-based asymmetrical multilayered composites doped with Na0.5Bi0.5TiO3 ceramic fibers. This innovative structure confers the PEI-based composites upon synergistic optimization of polarization intensity, breakdown strength and energy loss by designed interface effectiveness adopting tailored filler and interface configuration as modulation means, which can be further confirmed by finite element simulations and comparative experiments. The resultant composite film achieves an excellent Ue of 22.95 J cm-3 and an ultra-high η of 96.81% at ambient temperature, along with high-temperature performances of 12.88 J cm-3 and 79.26% at 150 °C, surpassing all previously reported polymer films in terms of both metrics. This study provides new insights for developing high-performance energy storage dielectrics suitable for practical applications.

A many-body energy decomposition analysis (MB-EDA) scheme based on a target state optimization self-consistent field (TSO-SCF) method.

In this paper, we combine an energy decomposition analysis (EDA) scheme with many-body expansion (MBE) to develop a MB-EDA method to study the cooperative and anti-cooperative effects in molecular cluster systems. Based on the target state optimization self-consistent field (TSO-SCF) method, the intermolecular interaction energy can be decomposed into five chemically meaningful terms, i.e., electrostatic, exchange, polarization, charge transfer and dispersion interaction energies. MB-EDA can decompose each of these terms in MBE. This MB-EDA has been applied to 3 different cluster systems: water clusters, ionic liquid clusters, and acetonitrile-methane clusters. This reveals that electrostatic, exchange, and dispersion interactions are highly pairwise additive in all systems. In water and ionic liquid clusters, the many-body effects are significant in both polarization and charge transfer interactions, but are cooperative and anti-cooperative, respectively. For acetonitrile-methane clusters, which do not involve hydrogen bonds or charge-charge Coulombic interactions, the many-body effects are quite small. The chemical origins of different many-body effects are deeply analyzed. The MB-EDA method has been implemented in Qbics (https://qbics.info) and can be a useful tool for understanding the many-body behavior in molecular aggregates at the quantum chemical level of theory.

Polarization effect induced by strain in hexagonal boron nitride nanoribbons

As a member of the hexagonal boron nitride (h-BN) system, boron nitride nanoribbons (BNNRs) have a BN polar covalent bonding infrastructure, and there are small-scale effects with strong correlation with piezoelectric effects as well as edge-strengthening quantum effects. However, realizing the polarization effect on BNNRs through experiments remains challenging. Here, we verify the strain-induced polarization effect on BNNRs through computational simulations and experiments. Using the ten-point iterative method, a computational model that can be used for the discrete difference of the polarization charge density and energy density of BNNRs is developed, and the correctness of the model for the polarization effect of Gaussian strain-induced BNNRs is verified by the computational programming in Python language. The polarization effects of strain-induced zigzag-edge BNNRs (ZBNNRs) for sawtooth strain, parabolic strain and oblique sawtooth strain are also investigated separately. In addition, the results of the computational simulations are experimentally verified to be consistent with the theoretical calculations. And the piezoelectric constant of − 276.88 pm∙V−1 for strained ZBNNRs is found to be four times higher than that of unstrained ZBNNRs. This study provides a relevant reference for the study of realizing the high integration of nano-scale h-BN based piezoelectricity for piezoelectricity.

An effective descriptor for the screening of electrolyte additives toward the stabilization of Zn metal anodes

In this work, the authors proposed desolvation activation energy as a critical descriptor for the screening of electrolyte additives, establishing a correlation between polarization and desolvation activation energy.

A Variational Approach to Excited Fermions on Kinks

We study the back-reaction of fermion fields on the kink solution in one space and one time dimension. We employ a variational procedure to determine an upper limit for the minimum of the total energy. This energy has three contributions: the classical kink energy, the energy of valence fermions and the fermion vacuum polarization energy. The latter arises from the interaction of the kink with the Dirac sea and is required for consistency of the semi-classical expansion for the fermions. Earlier studies only considered the valence part and observed a substantial back-reaction. This was reflected by a sizable distortion of the kink profile. We find that this distortion is strongly mitigated when the Dirac sea is properly accounted for. As a result, the back-reaction merely produces a slight squeeze or stretch of the kink profile.

Characteristics of flow field and various resistances of sandglass-type FPSO with special shape during towing process

For the new concept of floating production, storage and offloading unit (FPSO), the unique sandglass-type shape of its floating body can effectively reduce heave motion responses. However, this design feature may also generate distinct flow characteristics during towing. In this paper, the numerical method was established and validated to successfully predict the towing performance of the sandglass-type model by comparing it with the model experiment of a polar ocean nuclear energy platform with the sandglass-type shape. On this basis, the analysis incorporates both a local model of the underwater body without a free surface and a global model of the floating body with a free surface to analyze towing resistances. Specifically, the paper focuses on the frictional resistance and pressure resistance of sandglass-type models versus various draughts. Furthermore, the influence of free surface on various kinds of resistances and the towing resistances of sandglass-type FPSO with different speeds were studied. Finally, concluding remarks and future perspectives are presented.

Outstanding Energy-Storage Density Together with Efficiency of above 90% via Local Structure Design.

Dielectric ceramic capacitors with high recoverable energy density (Wrec) and efficiency (η) are of great significance in advanced electronic devices. However, it remains a challenge to achieve high Wrec and η parameters simultaneously. Herein, based on density functional theory calculations and local structure analysis, the feasibility of developing the aforementioned capacitors is demonstrated by considering Bi0.25Na0.25Ba0.5TiO3 (BNT-50BT) as a matrix material with large local polarization and structural distortion. Remarkable Wrec and η of 16.21 J/cm3 and 90.5% have been achieved in Bi0.25Na0.25Ba0.5Ti0.92Hf0.08O3 via simple chemical modification, which is the highest Wrec value among reported bulk ceramics with η greater than 90%. The examination results of local structures at lattice and atomic scales indicate that the disorderly polarization distribution and small nanoregion (∼3 nm) lead to low hysteresis and high efficiency. In turn, the drastic increase in local polarization activated via the ultrahigh electric field (80 kV/mm) leads to large polarization and superior energy storage density. Therefore, this study emphasizes that chemical design should be established on a clear understanding of the performance-related local structure to enable a targeted regulation of high-performance systems.

Review of Systematic Tendencies in (001), (011) and (111) Surfaces Using B3PW as Well as B3LYP Computations of BaTiO3, CaTiO3, PbTiO3, SrTiO3, BaZrO3, CaZrO3, PbZrO3 and SrZrO3 Perovskites.

We performed B3PW and B3LYP computations for BaTiO3 (BTO), CaTiO3 (CTO), PbTiO3 (PTO), SrTiO3 (STO), BaZrO3 (BZO), CaZrO3 (CZO), PbZrO3 (PZO) and SrZrO3 (SZO) perovskite neutral (001) along with polar (011) as well as (111) surfaces. For the neutral AO- as well as BO2-terminated (001) surfaces, in most cases, all upper-layer atoms relax inwards, although the second-layer atoms shift outwards. On the (001) BO2-terminated surface, the second-layer metal atoms, as a rule, exhibit larger atomic relaxations than the second-layer O atoms. For most ABO3 perovskites, the (001) surface rumpling s is bigger for the AO- than BO2-terminated surfaces. In contrast, the surface energies, for both (001) terminations, are practically identical. Conversely, different (011) surface terminations exhibit quite different surface energies for the O-terminated, A-terminated and BO-terminated surfaces. Our computed ABO3 perovskite (111) surface energies are always significantly larger than the neutral (001) as well as polar (011) surface energies. Our computed ABO3 perovskite bulk B-O chemical bond covalency increases near their neutral (001) and especially polar (011) surfaces.

Energetic binder - P(AMMO-ab-EG) alternate block copolyethers with strict controlled segment length

The flexibility of high energy polymers is hindered by bulky and polar high energy groups, resulting in reduced mechanical properties. In this paper, poly(3-azidomethyl-3-methyloxetane-glycol) (P(AMMO-ab-EG)) with an alternating block structure was synthesized and characterized. Diethylene glycol and triethylene glycol are used to improve flexibility, which length in this polymer structure is tightly controlled. (P(AMMO-ab-EG)) exhibits good flexibility, suitable viscosity and good thermal stability. It was found that P(AMMO-ab-DEG) exhibited a lower glass transition temperature but higher viscosity and better temperature viscosity sensitivity than P(AMMO-ab-TEG). These results demonstrate that fine tuning of the block length has a greater effect on Tg than on viscosity. This finding is of great significance to prepare energetic polymers with good processing properties and lower Tg value. Al, the prepared (P(AMMO-ab-EG) has excellent compatibility with NG (nitroglycerine) and NP (bis(2,2-dinitropropyl)acetal and bis(2,2- dinitropropyl)formal).

Stereo‐Active Lone Pairs Induced Giant Polarization in a 2D Ge‐Based Halide Perovskite Antiferroelectric

AbstractAntiferroelectrics, characterized by electrically controlled antipolar‐polar phase transformation, have attracted tremendous attention as a class of promising electroactive materials for assembling electronic devices. The emerging two‐dimensional (2D) halide perovskites with superior compositional diversity offer an ideal platform for exploring electroactive materials, whereas lead‐free antiferroelectric counterparts are still scarcely reported. Herein, for the first time, a new lead‐free 2D germanium iodide perovskite antiferroelectric (i‐BA)2CsGe2I7 (1, i‐BA is iso‐butylammonium) has been presented, which exhibits a high Curie temperature (Tc) up to 403 K. Remarkably, benefiting from the lone pair stereochemical activity in Ge2+ induced large structural distortion and Cs+ ion off‐center displacement, 1 shows well‐defined double P–E hysteresis loops in a wide temperature range with a giant maximum polarization up to 18.8 µC cm−2, which achieves a new high record among molecular antiferroelectrics. Moreover, under a low external electric field of 22.5 kV cm−1, the antipolar‐polar phase transformation in 1 affords a recoverable energy storage density Wrec of 0.27 J cm−3 and high storage efficiency up to 79.76%. Such lead‐free halide perovskite antiferroelectric with intriguing antiferroelectric behaviors, including high Tc, large polarization and remarkable energy storage properties, is exciting, which provides an alternative candidate for high‐performance antiferroelectrics for environmentally friendly electronic devices.

Structure-based identification of novel inhibitors targeting the enoyl-ACP reductase enzyme of Acinetobacter baumannii

Acinetobacter baumannii is a Gram-negative multidrug-resistant bacterial pathogen primarily associated with nosocomial infections resulting in increased morbidity and mortality in adults and infants, especially in sub-Saharan Africa where the clinical burden is high. New therapeutics are needed to treat multidrug-resistant Acinetobacter baumannii infections and reduce transmission. The study used computer-integrated drug discovery approaches including pharmacophore modelling, molecular docking, and molecular dynamics simulation to screen potential inhibitors against the enoyl-acyl carrier protein reductase—FabI protein of Acinetobacter baumannii. The top three potential inhibitors: 21272541 > 89795992 > 89792657 showed favourable binding free energies including coulombic energy, van der Waals energy, and polar and non-polar energies. Furthermore, all three complexes were extremely stable and compact with reduced fluctuations during the simulations period. Inhibitor 21272541 exhibited the highest binding affinity against the Acinetobacter baumannii FabI protein. This is similar to our recent report, which also identified 21272541 as the lead inhibitor against Klebsiella pneumoniae infections. Future clinical studies evaluating drug effectiveness should prioritise inhibitor 21272541 which could be effective in treating infections caused by Gram-negative organisms.

Computational explorations of the interaction between laccase and bisphenol A: influence of surfactant and different organic solvents

ABSTRACT Bisphenol A (BPA), as an environmental endocrine disruptor can cause damage to the reproductive, nervous and immune systems. Laccase can be used to degrade BPA. However, laccase is easily deactivated, especially in organic solvents, but the specific details are not clear. Molecular dynamics simulations were used to investigate the reasons for changes in laccase activity in acetonitrile (ACN) and dimethyl formamide (DMF) solutions. In addition, the effects of ACN and DMF on the activity of laccase and surfactant rhamnolipid (RL) on the degradation of BPA by laccase were investigated. Results showed that addition of ACN changed the structure of the laccase, not only decreasing the van der Waals interaction that promoted the binding of laccase with BPA, but also increasing the polar solvation free energy that hindered the binding of laccase with BPA, so it weakened the laccase activity. DMF greatly enhanced the van der Waals interaction between laccase and BPA, and played a positive role in their binding. The addition of surfactant RL alleviated the effect of organic solvent on the activity of laccase by changing the polar solvation energy. The mechanism of surfactant RL affecting laccase activity in ACN and DMF is described, providing support for understanding the effect of organic solvents on laccase.

Ba2+/Sr2+ regulation in A‐site vacancy‐engineered B0.015+1.5xS0.245‐1.5x□0.03BNT relaxor ceramics for energy storage

AbstractA‐site vacancy‐engineered Ba0.015+1.5xSr0.245‐1.5x□0.03Bi0.385Na0.325TiO3 (B0.015+1.5xS0.245‐1.5x□0.03BNT, x = 0, 0.012, 0.024, 0.036, 0.048, 0.06) ceramics were fabricated by a solid‐state reaction method. The effect of Ba/Sr regulation on the structure, polarization, and dielectric energy storage properties of the B0.015+1.5xS0.245‐1.5x□0.03BNT ceramics were investigated. With the increase of the x value, the lamellar microdomains transform into the coexistence of banded domains and nanodomains. A double‐like P‐E hysteresis loop with a high polarization value (Pmax > 35 μC/cm2) can be obtained at a very low electric field of 60 kV/cm. Consequently, a large recoverable energy storage density (Wrec = 2.33 J/cm3) can be achieved at a relatively low applied electric field of 130 kV/cm. The designed B0.087S0.173□0.03BNT also exhibits high dielectric constant (εr = 3510 @150°C&1 kHz) with suitable temperature capacitance coefficient (TCC150°C = ±15%) over the temperature range of 17°C∼382°C. These findings provide a novel vacancy‐engineered avenue towards the design of BSBNT relaxor ceramics with high Wrec and good stability for low‐voltage driven high‐temperature pulsed power capacitor.

Magnetoelectric Energy in Electrodynamics: Magnetoelectricity, Bi(an)isotropy, and Magnetoelectric Meta‐Atoms

AbstractMagnetoelectricity denotes the relationship between electric polarization and magnetization. In materials with an intrinsic magnetoelectric (ME) effect, the energy density comprises the polarization, magnetization, and ME energy densities. These three components of energy define local (subwavelength) characteristics of electromagnetic (EM) responses in multiferroic materials. In a subwavelength domain, coupling between the electric and magnetic dipole oscillations forms the ME field structures that are characterized by the violation of both spatial and temporal symmetry. Unlike multiferroics, bi(an)isotropic metamaterials are associated with an EM response characterized only by spatial symmetry breaking. This also applies to chiral materials. Since no “intrinsic magnetoelectricity” is assumed in such structures, any concepts about the stored ME energy are not applicable. This clearly points to the effect of nonlocality. That is why the basic concepts of bi(an)isotropy can only be analyzed by the EM far‐field characteristics. In this paper, it is argued that in the implementation of local (subwavelength) ME meta‐atoms and systems for near‐field probing of chirality, the concept on ME energy is crucial. Real ME energy can occur when ME fields in a singular subwavelength domain are characterized by a violation of both the symmetry of time reversal and spatial reflection.

In Vitro and In Silico Studies of Functionalized Polyurethane Surfaces toward Understanding Biologically Relevant Interactions.

The solid-aqueous boundary formed upon biomaterial implantation provides a playground for most biochemical reactions and physiological processes involved in implant-host interactions. Therefore, for biomaterial development, optimization, and application, it is essential to understand the biomaterial-water interface in depth. In this study, oxygen plasma-functionalized polyurethane surfaces that can be successfully utilized in contact with the tissue of the respiratory system were prepared and investigated. Through experiments, the influence of plasma treatment on the physicochemical properties of polyurethane was investigated by atomic force microscopy, attenuated total reflection infrared spectroscopy, differential thermal analysis, X-ray photoelectron spectroscopy, secondary ion mass spectrometry, and contact angle measurements, supplemented with biological tests using the A549 cell line and two bacteria strains (Staphylococcus aureus and Pseudomonas aeruginosa). The molecular interpretation of the experimental findings was achieved by molecular dynamics simulations employing newly developed, fully atomistic models of unmodified and plasma-functionalized polyurethane materials to characterize the polyurethane-water interfaces at the nanoscale in detail. The experimentally obtained polar and dispersive surface free energies were consistent with the calculated free energies, verifying the adequacy of the developed models. A 20% substitution of the polymeric chain termini by their oxidized variants was observed in the experimentally obtained plasma-modified polyurethane surface, indicating the surface saturation with oxygen-containing functional groups.

Enhanced high-temperature energy storage properties in BNT-based ceramics with well-controlled low dielectric loss

High-temperature resistance is one of the hot topics in the development of high-power density dielectric materials. It is still a great challenge for dielectric materials to meet the requirements of high energy density and low energy loss at high temperature. Based on the philosophy of increasing the Curie temperature and decreasing the dielectric loss at high temperature, a ceramic system of (1-x)Bi0.5Na0.5TiO3-xBi(Mg0.3Zr0.6)O3 ((1-x)BNT-xBMZ) is designed to improve the high-temperature energy storage properties. The Curie temperature was significantly increased from 320 °C to nearly 400 °C, and the dielectric loss was controlled below 5% up to 400 °C in the 0.92BNT-0.08BMZ ceramic. Due to the high Curie temperature and low dielectric loss, the maximum polarization and discharge energy density at 200 °C under 200 kV/cm of the 0.92BNT-0.08BMZ ceramic sample are as high as 48.79 μC/cm2 and 3.73 J/cm3, respectively. With the BMZ content increases, the changing rate of Pmax in the temperature range of 30∼200 °C decreases from 18.76% for the x = 0.06 ceramic to 10.27% for the x = 0.10 ceramic under 120 kV/cm, and the remanent polarization decreases from 5.23 μC/cm2 to 2.55 μC/cm2 at 200 °C, correspondingly. All these characteristics show that (1-x)BNT-xBMZ ceramics have broad application prospects in the field of high-temperature energy storage systems.

Study of self-assembling properties of HBc-VLP derivatives aided by molecular dynamic simulations from a thermodynamic perspective

Self-assembling protein nanoparticles showed promise for vaccine design due to efficient antigen presentations and safety. However, the unpredictable formations of epitopes-fused protein assemblies remain challenging in the upstream design. This study suggests employing molecular dynamic (MD) simulations to investigate the assembly properties of Hepatitis B core protein (HBc) from thermodynamic perspectives. Eight HBc derivatives were expressed in E. coli, with their self-assembly properties characterised by high-performance liquid chromatography and transmission electron microscopy. MD simulations on the dimers, based on AlphaFold-predicted 3D structures, analysed the derivative at the atomic level. Results revealed that HBc derivatives can form dissociative polymers or large multi-subunit structures due to assembly failures. The instability of the dimer in aqueous solvents or inappropriate intradimer distances could cause major assembly failures. Polar solvation energies played a vital role too in forming assemble-incompetent dimers. Importantly, our study demonstrated that MD simulations on dimers can provide preliminary predictions on the assembly properties of HBc derivatives, thus aiding vaccine design by lowering the risk of self-assembling failures in engineered proteins. Communicated by Ramaswamy H. Sarma