Enhancement Of Polarization Research Articles

Spin polarization and transport of hybrid interface states in π-stacked magnetic molecular junctions

Based on the first-principles method, the spin polarization and transport properties of the hybrid interface states (HIS) in π-stacked three-layer triphenylene molecular junction are studied theoretically. By rotating the torsion angle between two neighbor layers, the π-π interaction strength is adjusted. The results demonstrate that the HIS, generated by strong pz-d hybridization between molecules and ferromagnetic electrodes, can easily transfer to the central layer via a strong π-π interaction with similar spin polarization. A weak π-π interaction will block the transfer of the HIS, where the discrete molecular orbital states dominate the central molecule. However, an enhancement of the spin polarization for the molecular frontier orbital states is observed. The transport calculation shows that efficient transport of the HIS is realized in the π-stacked system, where the largest current appears at a strong π-π interaction but a significant current spin polarization appears at a weak π-π interaction. This work deepens our understanding of the role of the HIS in π-stacked organic systems.

Ultrahigh Capacitive Energy Storage in a Heterogeneous Nanolayered Composite

AbstractFerroelectric polymers with robust electrical polarization have been extensively investigated for capacitive energy storage. However, their inherent ferroelectric hysteresis loss limits the discharged energy density and compromises energy efficiency. Here, a heterogeneous nanolayered composite of ferroelectric polymer poly(vinylidene fluoride‐trifluoroethylene) (P(VDF‐TrFE)) and Al2O3 is presented, which effectively mitigates ferroelectric hysteresis loss while maintaining high polarization and enhanced breakdown strength. Phase‐field simulations indicate that the polarization behaviors of the heterogeneous layered structure are jointly influenced by the thickness and dielectric constant of each component, which balances the electrical energy and Landau energy within the heterogeneous system. Guided by the theoretical simulations, optimized polarization behaviors are achieved with a significant reduction in remnant polarization and ferroelectric loss in the P(VDF‐TrFE)/Al2O3 composites through careful control of P(VDF‐TrFE) thickness at nanometer scale. Moreover, the presence of multiple interfaces in the layered composites leads to a remarkable enhancement in polarization and breakdown strength. Consequently, an ultrahigh energy density of about 108 J cm−3 is achieved with a high charge–discharge efficiency of exceeding 80%. This work not only presents a straightforward approach to modify the polarization behaviors of ferroelectric polymers but also demonstrates a promising strategy for developing high‐energy‐density polymer nanocomposites.

Enhanced high-temperature energy storage performances in polymer dielectrics by synergistically optimizing band-gap and polarization of dipolar glass

Polymer dielectrics play an irreplaceable role in electrostatic capacitors in modern electrical systems, and have been intensively studied with their polarization and breakdown strength (Eb) optimized for high discharged energy density (Ud) at elevated temperatures. Small molecules have been explored as fillers, yet they deteriorate thermal stability of matrix which limits their optimal loading to ~1 wt%. Herein, we develop a polymer blend dielectric consisting of common polyimide and a bifunctional dipolar glass polymer which are synthesized from two small molecule components with wide band-gap and large dipole moment. The bifunctional dipolar glass with large molecular weight not only maintains thermal stability of polymer blends even at a high loading of 10 wt%, but also induces substantial enhancement in polarization and Eb than any of individual components does, achieving an ultrahigh Ud of 8.34 J cm−3 (150 °C) and 6.21 J cm−3 (200 °C) with a charge-discharge efficiency of 90%.

Oriented Crystal Polarization Tuning Bulk Charge and Single-Site Chemical State for Exceptional Hydrogen Photo-Production.

Rapid bulk charge recombination and mediocre surface catalytic sites harshly restrict the photocatalytic activities. Herein, the aforementioned concerns are well addressed by coupling macroscopic spontaneous polarization and atomic-site engineering of CdS single-crystal nanorods for superb H2 photo-production. The oriented growth of CdS nanorods along the polar axis, vectorially superimposing substantial polar units with orderly arrangement, renders a strong polarization electric field (20.1 times enhancement), which boosts bulk charge separation with an efficiency up to 72.4% (80.4-fold). Remarkably, polarization electric field alters the chemical state of Pt single sites by orderly reducing the binding energy of Pt atom with stepwise polarization enhancement of CdS substrate, which increases the onsite electron density of Pt from 10.232 to 10.261e- and *H key intermediates, providing preponderant Volmer-Tafel/Volmer-Heyrovsky reaction pathways with significantly decreased energy barriers for H2 production. Thus, highly polarized CdS nanorods with atomically dispersed Pt sites perform an outstanding H2 space-time yield of 118.5mmol g-1 h-1 and apparent quantum efficiency of 57.7% at λ = 420nm, and a record-high H2 turnover frequency of 57798.4 h-1, being one of the best catalysts for photocatalytic H2 evolution. This work highlights the function of polarization in manipulating charge separation and catalytic reaction.

Dielectric and photocatalytic characteristics of novel CaCu3Ti4O12 modified Ba0.5Sr0.5TiO3-based heterojunction synthesized by wet-chemistry method

The study presents a comprehensive investigation into the synthesis, characterization, and application of barium strontium titanate-calcium copper titanate (BST-CCTO) heterojunction, offering insights into their potential for high-energy-density capacitors and photocatalytic applications. It discusses the synthesis methods for BST, CCTO nanoparticles and their heterojunction. It delves into the structural analysis of prepared heterojunctions using techniques like X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The photocatalytic performance of heterojunctions, particularly in the degradation of organic dyes and pharmaceutical waste under visible light, is explored. Results demonstrate the superior photocatalytic efficiency of BST-CCTO heterojunction, i.e., B2 (99.5 % for RhB) compared to individual BST (78.4 %), suggesting potential applications in environmental remediation. This study also explores the development and properties of dielectric materials, particularly focusing on polyvinylidene fluoride (PVDF) and its composites with high-dielectric ceramics such as BST and CCTO. Various aspects of dielectric behavior, including polarization mechanisms and frequency dependence, are also discussed. Dielectric studies reveal the enhanced dielectric constant (50.93 at 1 kHz for 3 wt% loading of B3) of PBCT-3 composite as compared to pure PVDF composite (10 at 1 kHz), attributed to factors such as interface engineering, complementary electrical properties, and grain boundary effects. The mechanisms underlying the interaction between fillers and PVDF matrix are elucidated, highlighting the role of interface engineering and polarization enhancement in optimizing dielectric performance.

Local edge positioning effect modified carbon nitride for enhancing photocatalytic oxidation of trivalent arsenic

The highly symmetrical structure of heptazine in C3N4 often results in charge localization effects, which hinder the migration of carriers and the formation of active sites. In this study, well-designed C3N4 materials were prepared with carboxylic acid edge sites (ECCN) through a simple polycondensation method. DFT calculations and experimental results demonstrate that the presence of edge COOH units significantly disrupts carrier delocalization on the C3N4 framework, leading to an enhancement of material polarization and inherent electric field. This enhancement facilitates charge transfer and exciton dissociation. Moreover, it exerts a substantial impact on the surface characteristics of ECCN, promoting electron exchange and molecular polarization for As(III). Consequently, it improves capabilities for oxidizing trivalent arsenic by 4 times compared to pure C3N4. Our research represents significant progress in photocatalytic degradation of harmful compounds and provides enhanced understanding regarding control over carrier dynamics and surface reactivity.

Investigation of circularly polarized MIMO antenna with enhanced isolation for sub-6 GHz application

This article demonstrates the design process for a unique, two-port, circularly polarized (CP) multiple input multiple outputs (MIMO) antenna for fifth-generation (5G) applications operating at sub-6 GHz. The proposed 2-port CP MIMO antenna comprises a patch antenna with a distinctive slot and a circular split ring resonator (SRR) at the ground plane. The circular patch antenna’s resonant frequency is moved to a lower frequency by the addition of a circular SRR at the ground plane. Investigating a special slot at the patch antenna can help in the enhancement of circular polarization and bandwidth. A sequence of parasitic elements in the shape of ‘h’ is placed in the space between the two antenna elements for decoupling. The minimum 20 dB inter isolation among the antenna elements in the proposed 2-port CP MIMO antenna’s operating band is made possible by these h-shaped parasitic elements. In addition, to ensure the proposed antenna is more reliable for 5G applications at sub-6 GHz, other diversity parameters including Envelop Correlation Co-efficient (ECC), Mean Effective Gain (MEG), Diversity Gain (DG), TARC (Total Active Reflection Co-efficient) and CCL (channel capacity loss) are also calculated . In comparison to existing MIMO systems of the same order, the proposed 2-port CP MIMO antenna appears to have the minimum channel capacity loss and excellent diversity performance. The proposed 2-port CP MIMO antenna achieves an impedance bandwidth of 3.3 to 3.6 GHz with impedance matching better than 10 dB and has an axial ratio bandwidth of 3.35 to 3.51 GHz with a steady radiation pattern in both planes over the operating frequency bands.

Origin of ultrahigh-performance barium titanate-based piezoelectrics: Stannum-induced intrinsic and extrinsic contributions

Despite the pivotal role of stannum doping in achieving ultrahigh piezoelectric performance in barium titanate-based ceramics, the fundamental mechanisms underlying this enhancement remain elusive. Here, we introduce a single variable nonstoichiometric stannum strategy in lead-free barium titanate-based ceramics with giant piezoelectricity, revealing that stannum doping contributes intrinsically and extrinsically to enhance piezoelectricity. Density functional theory calculations elucidate the intrinsic enhancement of polarization arising from lattice distortion and increased space for titanium-oxygen bonds induced by optimal stannum doping, which is corroborated by Rayleigh analysis. A phase transition from ferroelectric multiphase coexistence to paraelectric phase is observed, alongside a rapid miniaturized and eventually disappeared domains with increasing stannum doping. This evolution in phase structure and domain configuration induces a nearly vanishing polarization anisotropy and low domain wall energy, facilitating easy polarization rotation and domain wall motion, thereby significantly contributing to the extrinsic piezoelectric response. Consequently, the origins of ultrahigh performance can be attributed to the synergistic effect of stannum-induced intrinsic and extrinsic contributions in barium titanate-based ceramics. This study provides fundamental insights into the role of doping elements and offers guidance for the design of high-performance piezoelectrics.

HCC-1 Accelerates Atherosclerosis by Inducing Endothelial Cell and Macrophage Pyroptosis and Serves as an Early Diagnostic Biomarker.

HCC-1 (hemofiltrate CC chemokine-1), a CC-type chemokine, exerts function to change intracellular calcium concentration, induce leukocyte, and manipulate enzyme release especially in monocytes. It has been reported that HCC-1 can predict the persistent acute kidney injury or suppress hepatocellular carcinoma by modulating cell cycle and promoting apoptosis; however, the effect of HCC-1 on atherosclerosis is poorly understood. Here, we aimed to clarify the function and mechanism of HCC-1 in atherosclerosis and whether it could serve as a novel biomarker for the diagnosis of atherosclerosis. HCC-1 expression in serum, atherosclerotic plaques, and normal arterial tissue from patients with atherosclerosis and control group was assessed by ELISA, immunohistochemistry and confocal microscope, and bioinformatic analysis. The atherosclerotic model of HCC-1 overexpressing and control mice was generated by tail vein injection of adeno-associated virus serotype 9-HCC-1 on an ApoE-/- background. Cell adhesion, polarization, and pyroptosis were evaluated in vitro. The relationship between HCC-1 concentration in serum and atherosclerosis was analyzed in patients with atherosclerosis. HCC-1 expression was positively correlated with the occurrence and stable-unstable switch of atherosclerosis under bioinformatic analysis, which is further supported by the results of increased HCC-1 expression in atherosclerosis patients both in serum and atherosclerotic plaque. adeno-associated virus serotype 9-HCC-1 mice had higher levels of inflammatory factors, increased macrophage accumulation and pyroptotic rate in plaque, and decreased atherosclerotic plaque stability. In vitro, HCC-1 promoted monocyte adhesion and M1 polarization and induced inflammation and pyroptosis both in endothelial cells and macrophages. HCC-1 expression was increased in patients with atherosclerosis, and HCC-1 overexpression accelerated atherosclerotic burden via an enhancement in monocyte recruitment, M1 polarization, and pyroptosis both in endothelial cells and macrophages. Our findings suggested that HCC-1 may serve as an early biomarker for the diagnosis of atherosclerosis, with the capacity to reflect the degree of stenosis.

Spatially Resolved Light-Induced Ferroelectric Polarization in α-In2Se3/Te Heterojunctions.

Light-induced ferroelectric polarization in 2D layered ferroelectric materials holds promise in photodetectors with multilevel current and reconfigurable capabilities. However, translating this potential into practical applications for high-density optoelectronic information storage remains challenging. In this work, an α-In2Se3/Te heterojunction design that demonstrates spatially resolved, multilevel, nonvolatile photoresponsivity is presented. Using photocurrent mapping, the spatially localized light-induced poling state (LIPS) is visualized in the junction region. This localized ferroelectric polarization induced by illumination enables the heterojunction to exhibit enhanced photoresponsivity. Unlike previous reports that observe multilevel polarization enhancement in electrical resistance, the device shows nonvolatile photoresponsivity enhancement under illumination. After polarization saturation, the photocurrent increases up to 1000 times, from 10-12 to 10-9 A under the irradiation of a 520nm laser with a power of 1.69 nW, compared to the initial state in a self-driven mode. The photodetector exhibits high detectivity of 4.6×1010 Jones, with a rise time of 27 µs and a fall time of 28 µs. Furthermore, the device's localized poling characteristics and multilevel photoresponse enable spatially multiplexed optical information storage. These results advance the understanding of LIPS in 2D ferroelectric materials, paving the way for optoelectronic information storage technologies.

Dope dyeing of tannic acid modified ultra‐high molecular weight polyethylene fabric

AbstractIn this study, we examined dyeing behavior of tannic acid modified ultra high molecular weight polyethylene fabric. Whole study was conducted to see the effect of tannic acid on dope dyeing performance of the fabric. Tannic acid and its complex with sodium salt TA‐Na+ complex were used for pretreatment. After dope dyeing, the color strength of fabrics, color fastness, surface morphology, and fiber structure were characterized by k/s value, color difference, scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS), and Fourier transform infrared spectroscopy (FTIR), respectively. The effect of treatment conditions was also discussed. The results had shown better color strength and washing fastness were obtained after tannic acid treatment, especially after TA‐Na+ complex treatment. SEM observation indicated the tannic acid adhesion on fabric surface. Both EDS and FTIR results showed the enhancement of surface polarity. And the UHMWPE fabric treated with 1% (w/v) TA‐Na+ with pH ranging 4–5 for 6 h showed better color durability over time. Approach was suitable because of sustainable, green behavior of tannic acid and entire process had a low cost.

Research on Underwater Imaging Technology Based on Polarization Enhancement

Research on Underwater Imaging Technology Based on Polarization Enhancement

Multidimensional Engineering Induced Interfacial Polarization by in-Situ Confined Growth of MoS2 Nanosheets for Enhanced Microwave Absorption.

Interface design has enormous potential for the enhancement of interfacial polarization and microwave absorption properties. However, the construction of interfaces is always limited in components of a single dimension. Developing systematic strategies to customize multidimensional interfaces and fully utilize advantages of low-dimensional materials remains challenging. Two-dimensional transition metal dichalcogenides (TMDCs) have garnered significant attention owing to their distinctive electrical conductivity and exceptional interfacial effects. In this study, a series of hollow TMDCs@C fibers are synthesized via sacrificial template of CdS and confined growth of TMDCs embedded in the fibers. The complex permittivity of the hollow TMDCs@C fibers can be adjusted by tuning the content of CdS templates. Importantly, the multidimensional interfaces of the fibers contribute to elevating the microwave absorption performance. Among the hollow TMDCs@C fibers, the minimum reflection loss (RLmin) of the hollow MoS2@C fibers can reach -52.0dB at the thickness of 2.5mm, with a broad effective absorption bandwidth of 4.56GHz at 2.0mm. This work establishes an alternative approach for constructing multidimensional coupling interfaces and optimizing TMDCs as microwave absorption materials.

Ferroelectric polarization and magnetic structure at domain walls in a multiferroic film

Domain walls affect significantly ferroelectric and magnetic properties of magnetoelectric multiferroics. The stereotype is that the ferroelectric polarization will reduce at the domain walls due to the incomplete shielding of depolarization field or the effects of gradient energy. By combining transmission electron microscopy and first-principles calculations, we demonstrate that the ferroelectric polarization of tail-to-tail 180° domain walls in ε-Fe2O3 is regulated by the bound charge density. A huge enhancement (43%) of ferroelectric polarization is observed in the type I domain wall with a low bound charge density, while the ferroelectric polarization is reduced to almost zero at the type II domain wall with a high bound charge density. The magnetic coupling across the type I and type II ferroelectric domain walls are antiferromagnetic and ferromagnetic, respectively. Revealing mechanisms for enhancing ferroelectric polarization and magnetic behaviors at ferroelectric domain walls may promote the fundamental research and potential applications of magnetoelectric multiferroics.

Carrier gradient core-double shell structure with heterojunction transition layer for significantly enhancing dielectric properties

In this work, to prohibit the undesirable large dielectric loss and electric-field distortion of the conductive fillers/polymer with a high dielectric constant, TiO2 (TO) and Al2O3 (AO) shells were successively coated on the surface of amorphous carbon (C) to prepare the C@TO@AO core-double shell nanoparticles. This novel design of gradually varying the multilayer hierarchical interface achieved the gradient reduction of carrier concentration from the C core to the TO and AO layers. And the introduction of the multilayer hierarchical interface was advantageous to the enhancement of interface polarization. Moreover, the excellent integrated dielectric properties could be effectively achieved by adjusting the layer thickness and crystal structure of the TO layer. It was worth noting that the TO transition layer with anatase and rutile heterojunctions (HTO) had a significant enhancement in the dielectric constant of the composites induced by the strength of interfacial polarization and built-in electric field inside the HTO layer. Furthermore, the simulated electric field distribution inside the composites was further investigated to reveal the mechanism of enhanced dielectric properties. This work exerts important guiding significance for the reasonable structure design and the elaborate regulation of the shell micro-structures to improve the dielectric properties of composites.

Partitioning polar-slush strategy in relaxors leads to large energy-storage capability.

Relaxor ferroelectric (RFE) films are promising energy-storage candidates for miniaturizing high-power electronic systems, which is credited to their high energy density (Ue) and efficiency. However, advancing their Ue beyond 200 joules per cubic centimeter is challenging, limiting their potential for next-generation energy-storage devices. We implemented a partitioning polar-slush strategy in RFEs to push the boundary of Ue. Guided by phase-field simulations, we designed and fabricated high-performance Bi(Mg0.5Ti0.5)O3-SrTiO3-based RFE films with isolated slush-like polar clusters, which were realized through suppression of the nonpolar cubic matrix and introduction of highly insulating networks. The simultaneous enhancement of the reversible polarization and breakdown strength leads to a Ue of 202 joules per cubic centimeter with a high efficiency of ~79%. The proposed strategy provides a design freedom for next-generation high-performance dielectrics.

Tailoring ferroelectricity in P(VDF/TrFE) thin films: Unveiling the hidden role of cooling rate

P(VDF/TrFE), a versatile ferroelectric polymer, holds immense promise for diverse applications, but optimizing its ferroelectric properties has been a major bottleneck. We present a groundbreaking approach, demonstrating a remarkable 48 % enhancement in polarization through a precise control of the cooling rate after annealing. Slow cooling at 0.5 °C/min significantly enhances the β-phase crystallinity, the ferroelectrically active phase, as evidenced by X-ray diffraction. This improved crystallinity directly contributes to the observed polarization enhancement. Dielectric analysis reveals a strong link between cooling rate and molecular alignment, with slower cooling leading to a higher dielectric constant, indicative of superior chain order. This improved order facilitates more efficient polarization switching, further contributing to the enhanced ferroelectricity. Our study unveils the often-overlooked impact of cooling rate on the ferroelectric properties of P(VDF/TrFE) thin films. By manipulating the cooling speed after annealing, we can effectively tailor the material's ferroelectricity, opening new avenues for optimizing device performance and expanding its application potential.

Microstructure‐Tuned Amorphous Co2FeGe Nanoflakes for Enhanced Microwave Absorption Via Mechanical Alloying

Herein, a simple strategy for fabricating amorphous Co2FeGe nanoflakes by tuning the milling time with mechanical alloying method to enhance the microwave absorption capabilities is presented. These alloys exhibit soft magnetic properties characterized by high saturation magnetization and low coercivity. The enhancement of polarization and resonance effects, leading to improved magnetic and dielectric loss, is attributed to the refinement of crystalline size and the substantial aspect ratio of flaky particles. The minimum reflection loss reaches −48.6 dB at 4.92 GHz with an effective absorption bandwidth of 2.88 GHz in the C‐band. Due to its high Curie temperature, Co2FeGe exhibits considerable potential for maintaining highly efficient microwave absorption capabilities under high‐temperature conditions, thereby providing a novel perspective and technical means for the development of new high‐temperature‐resistant, high‐performance microwave‐absorbing materials. This is expected to play a significant role in future high‐temperature electronic countermeasure systems.

Highly luminescent, fast switching electro-optical device based on core-shell bimetallic nanoparticles/ ferroelectric liquid crystal composites.

Owing to the passive nature of liquid crystal (LC) materials, achieving luminous displays using pure LC materials is challenging. In addition, it is difficult to achieve a fast switching time using pristine ferroelectric LC devices without compromising their cell thickness. Herein, we have developed a fast switching and highly luminescent electro-optical device by dispersing a minute concentration of bimetallic nanoparticles (Au@Ag NPs) having a spherical gold core and a silver shell within a ferroelectric liquid crystal (FLC) host matrix, ZLI3654. Au@Ag core-shell NPs having synergic attributes of both counterparts were successfully synthesized by a facile seed-mediated route. The Au core helps to tune the shape of the Ag shell and provides enhanced electron density as well as improved stability against oxidation. Introducing nanoparticles induces little structural modifications to the host FLC, resulting in an improvement in the mesogenic alignment. Interestingly, ∼29-fold enhancement in the photoluminescence (PL) intensity is observed on dispersing 0.25 wt% of Au@Ag NPs into the FLC host matrix. The enhanced electromagnetic field in the FLC-nanocomposite is attributed to the Localized Surface Plasmon Resonance of Au@Ag NPs, which strengthens the photon absorption rates by the FLC molecules, culminating in the massive enrichment of the PL intensity. In addition, the improved localized electric field inside the FLC device led to a noticeable enhancement in the spontaneous polarization, dielectric permittivity, and, most interestingly, ∼53% fastening in the switching time at an optimum concentration (0.25 wt%) of Au@Ag NPs. The improved electro-optical parameters of the Au@Ag NPs/FLC composite have been compared with the performance of both pristine Au NPs/FLC and Ag NPs/FLC composites, respectively, for the comprehensiveness of the study. The present study paves a systematic way to develop FLC-based advanced electro-optical devices with faster switching and higher luminescence properties.

Nonvolatile Control of Valley Polarized Emission in 2D WSe2-AlScN Heterostructures.

Achieving robust and electrically controlled valley polarization in monolayer transition metal dichalcogenides (ML-TMDs) is a frontier challenge for realistic valleytronic applications. Theoretical investigations show that the integration of 2D materials with ferroelectrics is a promising strategy; however, an experimental demonstration has remained elusive. Here, we fabricate ferroelectric field-effect transistors using a ML-WSe2 channel and an Al0.68Sc0.32N (AlScN) ferroelectric dielectric and experimentally demonstrate efficient tuning as well as non-volatile control of valley polarization. We measure a large array of transistors and obtain a maximum valley polarization of ∼27% at 80 K with stable retention up to 5400 s. The enhancement in the valley polarization is ascribed to the efficient exciton-to-trion (X-T) conversion and its coupling with an out-of-plane electric field, viz., the quantum-confined Stark effect. This changes the valley depolarization pathway from strong exchange interactions to slow spin-flip intervalley scattering. Our research demonstrates a promising approach for achieving non-volatile control over valley polarization for practical valleytronic device applications.