Large Radius Research Articles

BaPb2(CO3)2F2: Enhancing Birefringence by a Multiunit Synergy Effect.

Carbonates are ideal birefringent materials because their π-conjugated [CO3] groups are beneficial for large anisotropy. How to maximize the birefringence and maintain a wide transmittance simultaneously in carbonates is a great challenge. Adopting a multiple-functional group synergy strategy by combining alkaline-earth metal Ba2+ with large ion radius, PbO6F distorted hexagonal pyramid, and paralleled π-conjugated CO3 triangles together, we synthesized a new metal carbonate crystal, BaPb2(CO3)2F2. BaPb2(CO3)2F2 features a typical two-dimensional layered structure, which consists of a PbCO3F monolayer parallel to the ab plane and Ba2+ cations filled between the monolayers. BaPb2(CO3)2F2 exhibits a large experimental birefringence of approximately 0.245@546 nm and a short ultraviolet absorption edge down to 264 nm (Eg = 4.70 eV), indicating that it is a promising ultraviolet birefringent material. The reported highest experimental birefringence index among carbonate crystals is surpassed by BaPb2(CO3)2F2. The theoretical calculation shows that the contribution percentages for total birefringence are 57 and 43% for the CO3 group and PbO3F group, respectively. Our work offers a new route for designing new birefringent materials with excellent comprehensive performance.

Vibrational Spectroscopy of Perovskite Ferroelectrics

Ferroelectric and antiferroelectric materials are technologically important by the richness of applications such as piezoelectric, pyroelectric, electro-optic, elasto-optic, and nonlinear optic effects. Especially, oxides with a perovskite structure are very important. Its chemical formula is ABO3, where A is a cation with a larger ionic radius, and B is a cation with a smaller ionic radius. Various elements are available in A- and B-sites. For example, the large piezoelectricity of well-known Pb(ZrxTi1−x)O3 (PZT) solid solutions was found in a morphotropic phase boundary (MPB). The very high dielectric constant, colossal piezoelectric effect, and large electro-optic effect are induced by ferroelectric phase transitions. Such excellent functionalities are closely related to lattice dynamical instability. The vibrational spectroscopy, i.e., Raman scattering, Brillouin scattering, far-infrared, and terahertz time-domain spectroscopy, is a powerful tool for lattice dynamical anomalies. This paper intended a brief review of vibrational spectroscopy on ferroelectric phase transitions of advanced perovskite oxides.

Ab-initio atomistic insights into lead-free perovskites for Photovoltaics Technology

The primary objective of this manuscript is to enhance knowledge and comprehension of hexagonal perovskites KNiX3 (X=I, Br). The world is fascinated by halide perovskites because of their advancements in opto-electronic applications, particularly in the photovoltaic field. KNiI3 and KNiBr3 halide perovskites correspond to the two anion I and Br. Here we aim to investigate how opto-electronic applications are affected by the substitution of cations and anion. Within the framework of density functional theory (DFT), the structural, electronic, and optical properties have been computed using the PBE GGA approximation. Br-based perovskites have a shorter bond length than I-based compounds because iodine ions have a larger ionic radius than bromine ions. Thus, the lattice constant increases from I-based potassium halide perovskites to Br-based potassium halide perovskites. The values of the lattice constant match the results of experimental computations. The Density of States (DOS) curves and band structure are used to examine the contribution of the bands. From Br to I, there is a reduction in the band gap, indicating an improvement in photovoltaic applications. Various energy ranges are used to calculate the optical spectra, dielectric function, absorption coefficient, optical reflectivity, and refractive index. KNiX3 (X=I, Br) compound reveals low reflection value which is typically an excellent choice for photovoltaic and opto-electronic applications.

Symmetric comet-type periodic orbits in the elliptic three-dimensional restricted (N+1)-body problem

For N≥3, we show the existence of symmetric periodic orbits of very large radii in the elliptic three-dimensional restricted (N+1)-body problem when the N primaries have equal masses and are arranged in a N-gon central configuration. These periodic orbits are close to very large circular Keplerian orbits lying nearly a plane perpendicular to that of the primaries. They exist for a discrete sequence of values of the mean motion, no matter the value of the eccentricity of the primaries.

Flower-like graphitic carbon derived from biomass for anode of potassium ion battery

The conventional graphite anode for potassium ion batteries (PIBs) can be structurally disrupted by intercalation of potassium ion with a large radius, resulting in the poor cycling stability and rate capability. Here an architecture of flower-like graphitic carbon (FLGC) derived from biomass is designed. As the anode for PIBs, FLGC achieves the stable performance and high-rate capability because of numerous mesopores, intrinsic defects, and a large interlayer spacing. FLGC presents a stable cycling performance (171mAh g−1 after 1700 cycles at 500 mA g−1 with a capacity retention of 79.2 %) and a high potassium storage capacity (301mAh g−1 at 100 mA g−1), in addition to low charge/discharge plateaus (0.35 V for charge and 0.12 V for discharge). More importantly, the mechanism for potassium storage and influence of intrinsic defects on the electrochemical performance are investigated. This study offers a novel design for graphitic structures, which is important for PIBs.

Cloud Droplet Size Distributions Governed by Condensation, Collision–Coalescence, and Sedimentation. Part II: Analytical Expressions for Size Distribution Shape and Asymptotic Behavior for Large-Droplet Tails

Abstract Droplet growth via condensation and collision–coalescence has been investigated in the limit of very weak coalescence growth: a collector-mode approximation emerges for coalescence growth that consists solely of droplets in the tail collecting droplets near the main mode of the cloud droplet size distribution and that does not deplete the mode. In this second part, the approximation is formalized, leading to a simplified form of the collision–coalescence term in the equation governing the evolution of the droplet size distribution. This form allows for analytical solutions for transient growth and for steady-state distributions representing a balance between condensation, collision–coalescence growth, and removal by sedimentation. The solutions lead to an expression for the drizzle growth time, formally, the finite time in which a droplet approaches infinite size. The drizzle growth time is related to a transition radius at which droplet growth switches from condensation-dominated to coalescence-dominated. The solutions also provide a dimensionless group that governs the steady-state distribution shape, which is referred to as the drizzle number. The solutions are checked by comparing to a Monte Carlo model developed in part 1, and it is found that the analytical solution is excellent when the drizzle number is much greater than unity, which is the typical situation for the microphysical conditions achievable in a convection–cloud chamber. The steady-state size distribution has the form of a modified gamma distribution, with a transition to a power-law tail at a sufficiently large radius. The solutions are not only formally valid for a convection–cloud chamber but can also be extended to shallow, mixed-layer clouds such as mixing fogs.

Experimental measurement of electric field near the insulator string

This paper explores the electric field distribution near a string of six NJ120 high voltage insulators through experimental measurements under various conditions. Using a distributed capacitance method with custom probes connected to an Arduino-based system, tests were conducted on clean and polluted insulators. Pollution was simulated using a tuf-based solution with conductivities ranging from 0.5 to 1.97 mS/cm. Measurements were taken at 13 heights and four distances (1 to1.75 m) under applied AC voltages of 15 to 80 kV. The study also investigates the effects of damaged insulators, placed at different positions (near the high voltage terminal, in the middle, and near the ground), as well as the role of guard rings in improving field uniformity. Results indicate that pollution and damaged insulators significantly increased field intensity, particularly near the high voltage terminal. Guard rings effectively reduced field peaks, with larger radii and optimal placement providing the best performance. These findings contribute to optimizing high voltage insulator design for enhanced reliability.

Co-insertion chemistry boosting site activity and structural stability of nickel hexacyanoferrate for superior aqueous ammonium ion storage

Aqueous ammonium ion batteries (AAIBs) are promising candidates for large-scale energy storage because of their low cost, exceptional safety, and rapid ion diffusion. However, the large ionic radius of NH4+ (1.43 Å) leads to structural damage and limited transport dynamics of cathode materials. In this study, a K+ pre-intercalated Prussian blue analogue (KNiHCF) cathode is designed, which co-inserts NH4+/K+ during cycling process. Density functional theory calculations demonstrate that NH4+/K+ co-insertion, as compared with pure NH4+ insertion, enhances the binding interaction of guest ions to the host materials, improves structural stability and promotes ion diffusion. Moreover, dual-ion co-insertion can effectively improve the electrochemical kinetics and site activity of [Fe(CN)6]3−/[Fe(CN)6]4−, revealing the two-phase transition mechanism during cycling. Therefore, KNiHCF exhibits a superior ammonium ion storage performance (63.9 mA h g−1 at 60 mA g−1). KNiHCF cathodes, as compared with other similar cathodes, exhibit excellent cycling stability (77.3 % after 3000 cycles at 3000 mA g−1). Additionally, assembled KNiHCF//activated carbon (AC) hybrid capacitors exhibit an extraordinary capacity retention of 94.9 % after 4000 cycles at 1000 mA g−1. Thus, this study provides new insights into the storage mechanisms of AAIBs.

Multiple Redox‐Active Centers in An Azatriangulenetrione‐Based Covalent Organic Framework for High‐Capacity, High‐Rate and Ultra‐Stable Sodium‐Ion Batteries

Sodium‐ion batteries (SIBs) suffer from sluggish kinetics, large volume change, and limited specific capacity due to the large radius of Na+. These issues can be solved through using covalent organic frameworks (COFs) as electrodes. Herein, an azatriangulenetrione‐containing COF (denoted as CityU‐33) was designed and synthesized as an electrode material for SIBs. Due to its inherent abundance of multiple redox‐active sites and fast intercalation kinetics, CityU‐33 delivered a high discharge capacity of 410.4 mAh g‐1 at 0.1 A g‐1 and showed remarkable long‐term cycling stability, where a discharge capacity of 313 mAh g‐1 at 0.2 A g‐1 with approximately 100% retention over 1700 cycles was achieved, making it the top COF electrode material for SIBs.

Multiple Redox-Active Centers in An Azatriangulenetrione-Based Covalent Organic Framework for High-Capacity, High-Rate and Ultra-Stable Sodium-Ion Batteries.

Sodium-ion batteries (SIBs) suffer from sluggish kinetics, large volume change, and limited specific capacity due to the large radius of Na+. These issues can be solved through using covalent organic frameworks (COFs) as electrodes. Herein, an azatriangulenetrione-containing COF (denoted as CityU-33) was designed and synthesized as an electrode material for SIBs. Due to its inherent abundance of multiple redox-active sites and fast intercalation kinetics, CityU-33 delivered a high discharge capacity of 410.4 mAh g-1 at 0.1 A g-1 and showed remarkable long-term cycling stability, where a discharge capacity of 313 mAh g-1 at 0.2 A g-1 with approximately 100% retention over 1700 cycles was achieved, making it the top COF electrode material for SIBs.

Gas thermodynamics meets galaxy kinematics: Joint mass measurements for eROSITA galaxy clusters

The mass of galaxy clusters is a critical quantity for probing cluster cosmology and testing theories of gravity, but its measurement could be biased, given that assumptions are inevitable in order to make use of any approach. In this paper, we employ and compare two mass proxies for galaxy clusters: thermodynamics of the intracluster medium and kinematics of member galaxies. We selected 22 galaxy clusters from the cluster catalog in the first SRG/eROSITA All-Sky Survey (eRASS1) that have sufficient optical and near-infrared observations. We generated multiband images in the energy range of (0.3, 7) keV for each cluster, and derived their temperature profiles, gas mass profiles, and hydrostatic mass profiles using a parametric approach that does not assume dark matter halo models. With spectroscopically confirmed member galaxies collected from multiple surveys, we numerically solved the spherical Jeans equation for their dynamical mass profiles. Our results quantify the correlation between dynamical mass and the line-of-sight velocity dispersion, $ dyn los ^2r_ proj /G) - (3.87 with a root mean square (rms) scatter of 0.14 dex. We find that the two mass proxies lead to roughly the same total mass, with no observed systematic bias. As such, the $ tension is not specific to hydrostatic mass or weak lensing shears, but also appears with galaxy kinematics. Interestingly, the hydrostatic-to-dynamical mass ratios decrease slightly toward large radii, which could possibly be evidence for accreting galaxies in the outskirts. We also compared our hydrostatic masses with the latest weak lensing masses inferred with scaling relations. The comparison shows that the weak lensing mass is significantly higher than our hydrostatic mass by sim 110<!PCT!>. This might explain the significantly larger value of $ from the latest measurement using eRASS1 clusters than almost all previous estimates in the literature. Finally, we tested the radial acceleration relation established in disk galaxies. We confirm the missing baryon problem in the inner region of galaxy clusters using three independent mass proxies for the first time. As ongoing and planned surveys are providing deeper X-ray observations and more galaxy spectra for cluster members, we expect to extend the study to cluster outskirts in the near future.

Euclid: Early Release Observations -- The intracluster light and intracluster globular clusters of the Perseus cluster

We study the intracluster light (ICL) and intracluster globular clusters (ICGCs) in the nearby Perseus cluster of galaxies using Early Release Observations. By modelling the isophotal and iso-density contours, we mapped the distributions and properties of the ICL and ICGCs out to radii of $200$--$600$\,kpc (up to $ $ of the virial radius, depending on the parameter) from the brightest cluster galaxy (BCG). We find that the central 500\,kpc of the Perseus cluster hosts $70\,000 globular clusters, and $1.7 odot $ of diffuse light from the BCG+ICL in the near-infrared This accounts for $38 of the cluster's total stellar luminosity within this radius. The ICL and ICGCs share a coherent spatial distribution which suggests that they have a common origin or that a common potential governs their distribution. Their contours on the largest scales ($>200$\,kpc) are not centred on the BCG's core, but are instead offset westwards by 60\,kpc towards several luminous cluster galaxies. This offset is opposite to the displacement observed in the gaseous intracluster medium. The radial surface brightness profile of the BCG+ICL is best described by a double S\'ersic model, with $68 of the light contained in the extended, outer component. The transition between these components occurs at approx 60\,kpc, beyond which the isophotes become increasingly elliptical and off-centred. Furthermore, the radial ICGC number density profile closely follows the profile of the BCG+ICL only beyond this 60\,kpc radius, where we find an average of 60--80 globular clusters per $10^9$\,M$_ of diffuse stellar mass. The BCG+ICL colour becomes increasingly blue with radius, consistent with the stellar populations in the ICL having subsolar metallicities Fe/H to $-1.0$. The colour of the ICL, and the specific frequency and luminosity function of the ICGCs suggest that the ICL+ICGCs were tidally stripped from the outskirts of massive satellites with masses of a few $ $\,M$_ with an increasing contribution from dwarf galaxies at large radii.

Preparation and Characterization of Temperature-Sensitive Gel Plugging Agent.

In order to use intelligent gel systems to realize deep source water control in medium and high water cut reservoirs, and also to solve the shortcomings of conventional gels, such as the high chemical dose required, large profile control radius, poor temperature resistance, shear resistance, and plugging performance, a temperature-sensitive gel based on natural cellulose was developed, and the temperature resistance, rheological performance, and plugging performance of the temperature-sensitive gel were tested and evaluated. The results show that the system can maintain a viscosity retention rate of up to 95% after high-temperature aging at 90-120 °C for 50 days. When using medium- to low-salinity calcium chloride formation water for preparation, the gelation effect is good. The rheometer oscillation frequency scanning test shows that the system gel is a strong elastic body dominated by elasticity. The core displacement experiment shows that the highest sealing rate of the system is 97%, and the breakthrough pressure can reach 2.5 MPa at this time. The microstructure of the gel system was tested by infrared, and it was found that the gel system had strong hydrogen bonding and the gel had good stability. The research results contribute to improving the recovery rate of high water cut oil reservoirs.

On the two-dimensional harmonic oscillator with an electric field confined to a circular box

Abstract We revisit the quantum-mechanical two-dimensional harmonic oscillator with an electric field confined to a circular box of impenetrable walls. In order to obtain the energy spectrum we resort to the Rayleigh-Ritz method with polynomial and Gaussian basis sets. We compare present results with those derived recently by other authors. We discuss the limits of large and small box radius and also do some calculations with perturbation theory.

A Novel Anion Receptor Additive for −40 °C Sodium Metal Batteries by Anion/Cation Solvation Engineering

AbstractSodium metal batteries, known for their high theoretical specific capacity, abundant reserves, and promising low‐temperature performance, have garnered significant attention. However, the large ionic radius of Na+ and sluggish transport kinetics across the interfacial structure hinder their practical application. Previous reviews have rarely regulated electrolyte performance from the perspective of anions, as important components of the electrolyte, the regulation mechanism is not well understood. Herein, a novel anion receptor additive, 4‐aminophenylboronic acid pinacol ester (ABAPE), is proposed to weaken the coupling between anions and cations and accelerate Na+ transport kinetics. The results of theoretical calculations and X‐ray photoelectron spectroscopy with deep Ar‐ion etching demonstrate that the introduction of this additive alters the solvation structure of Na+, reduces the desolvation barrier and forms a stable and dense electrode‐electrolyte interface. Moreover, ABAPE forms hydrogen bonds (−NH ⋅ ⋅ ⋅ O/F) with H2O/HF, effectively preventing the hydrolysis of NaPF6 and stabilizing acidic species. Consequently, the Na||Na symmetric cell exhibits excellent long‐cycle performance of 500 h at 1 mA cm−2 and 0.5 mAh cm−2. The Na||Na3V2(PO4)3 (NVP) cell with the addition of ABAPE maintains a capacity retention of 84.29 % at 1 C after 1200 cycles and presents no capacity decay over 150 cycles at −40 °C.

A Novel Anion Receptor Additive for -40ºCSodium MetalBatteriesby Anion/Cation Solvation Engineering.

Sodium metal batteries, known for their high theoretical specific capacity, abundant reserves,and promisinglow-temperature performance, have garnered significant attention. However, the large ionic radius of Na+and sluggish transport kinetics across the interfacial structure hinder their practical application.Previous reviews have rarely regulated electrolyte performance from the perspective of anions; as important components of the electrolyte, the regulation mechanism is not well understood. Herein, a novel anion receptor additive, 4-aminophenylboronic acid pinalol ester (ABAPE), is proposed to weaken the coupling between anions and cations and accelerateNa+transport kinetics.The results of theoretical calculations and X-ray photoelectron spectroscopy with deep Ar-ion etching demonstrate thatthe introduction of this additive alters the solvation structure of Na+, reducesthe desolvation barrier and formsa stable and dense electrode-electrolyte interface. Moreover, ABAPE forms hydrogen bonds (-NH···O/F) with H2O/HF, effectively preventing the hydrolysis of NaPF6and stabilizing acidic species. Consequently, the Na||Na symmetric cell exhibits excellent long-cycle performance of 500 h at 1 mA cm-2 and 0.5 mAh cm-2. The Na||Na3V2(PO4)3(NVP) full cell with the addition of ABAPE maintains a capacity retention of 84.29% at 1 C after1200 cycles and presents no capacity decayover 150 cycles at -40°C.

Unravelling the Electrical Field Induced Ion Migration in Flexible OLEDs with PEDOT:PSS Electrodes.

The development of flexible organic light-emitting didoes (FOLEDs) has spurred the research on flexible transparent electrodes (FTEs). Poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) is one of the most attractive FTEs due to its adjustable conductivity and compatibility with low-cost and large-scale solution processing techniques. Significantly, highly efficient FOLEDs have been achieved with modified PEDOT:PSS FTEs. However, the intrinsic mechanisms that contribute to device degradation of FOLEDs utilizing PEDOT:PSS FTEs have not yet been fully elucidated. In this work, three ionic liquids (ILs) are used to enhance the electrical conductivity and mechanical flexibility of PEDOT:PSS FTEs. Simultaneously, the influence of the electric field induced ion migration from PEDOT:PSS FTEs on the operational stability of FOLEDs is unraveled. We find that the ILs with larger ionic radii and higher steric hindrance are beneficial to suppressing the electrical field induced ion migration and improving the operational stability of FOLEDs. Finally, large-area and high-performance FOLEDs are achieved based on the IL of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide modified PEDOT:PSS FTEs, which demonstrate a high current efficiency of 98.1 cd/A and a longer lifetime of 66.7 min. This finding may promote the practical application of PEDOT:PSS FTEs in flexible optoelectronics.

The inflated, eccentric warm Jupiter TOI-4914 b orbiting a metal-poor star, and the hot Jupiters TOI-2714 b and TOI-2981 b

Recent observations of giant planets have revealed unexpected bulk densities. Hot Jupiters, in particular, appear larger than expected for their masses compared to planetary evolution models, while warm Jupiters seem denser than expected. These differences are often attributed to the influence of the stellar incident flux, but it has been unclear if they also result from different planet formation processes, and if there is a trend linking the planetary density to the chemical composition of the host star. In this work, we present the confirmation of three giant planets in orbit around solar analogue stars. TOI-2714 b (P ≃ 2.5 d, Rp ≃ 1.22 RJ, Mp = 0.72 MJ) and TOI-2981 b (P ≃ 3.6 d, RP ≃ 1.2 RJ, MP = 2 MJ) are hot Jupiters on nearly circular orbits, while TOI-4914 b (P ≃ 10.6 d, RP ≃ 1.15 RJ, Mp = 0.72 MJ) is a warm Jupiter with a significant eccentricity (e = 0.41 ± 0.02) that orbits a star more metal-poor ([Fe/H] = −0.13) than most of the stars known to host giant planets. Similarly, TOI-2981 b orbits a metal-poor star ([Fe/H] = −0.11), while TOI-2714 b orbits a metal-rich star ([Fe/H] = 0.30). Our radial velocity follow-up with the HARPS spectrograph allows us to detect their Keplerian signals at high significance (7, 30, and 23σ, respectively) and to place a strong constraint on the eccentricity of TOI-4914 b (18σ). TOI-4914 b, with its large radius (Rp ≃ 1.15 RJ) and low insolation flux (F⋆ < 2 × 108 erg s−1 cm−2), appears to be more inflated than what is supported by current theoretical models for giant planets. Moreover, it does not conform to the previously noted trend that warm giant planets orbiting metal-poor stars have low eccentricities. This study thus provides insights into the diverse orbital characteristics and formation processes of giant exoplanets, in particular the role of stellar metallicity in the evolution of planetary systems.

Photometric properties of classical bulge and pseudo-bulge galaxies at 0.5 ≤ z < 1.0

Context. We compare the photometric properties and specific star formation rate (sSFR) of classical- and pseudo-bulge galaxies with M∗ ≥ 109.5 M⊙ at 0.5 ≤ z < 1.0, selected from all five CANDELS fields. We also compare these properties of bulge galaxies at lower redshift selected from MaNGA survey in previous work. Aims. This paper aims to study the properties of galaxies with classical and pseudo-bulges at intermediate redshift, to compare the differences between different bulge types, and to understand the evolution of bulges with redshift. Methods. Galaxies are classified into classical bulge and pseudo-bulge samples according to the Sérsic index n of the bulge component based on results of two-component decomposition of galaxies, as well as the position of bulges on the Kormendy diagram. For the 105 classical bulge and 86 pseudo-bulge galaxies selected, we compare their size, luminosity, and sSFR of various components. Results. At a given stellar mass, most classical bulge galaxies have smaller effective radii, larger B/T, brighter and relatively larger bulges, and less active star formation than pseudo-bulge galaxies. In addition, the two types of galaxies have larger differences in sSFR at large radii than at the central region at both low- and mid-redshifts. Conclusions. The differences between the properties of the two types of bulge galaxies are generally smaller at mid-redshift than at low-redshift, indicating that they are evolving to more distinct populations towards the local universe. Bulge type is correlated with the properties of their outer disks, and the correlation is already present at redshifts as high as 0.5 < z < 1.

Cu@Cu31S16 cathode for high-performance aqueous zinc-ion battery

Abstract Among various battery systems, aqueous zinc-ion batteries demonstrate significant potential for large-scale energy storage applications. However, the relatively large radius of zinc ions makes it challenging for them to intercalate into cathode materials, resulting in a limited variety of host materials suitable for Zn2+ storage. Therefore, researching appropriate cathode materials is a crucial component of the practical application of aqueous zinc-ion batteries. In this study, we prepare two binderless, conductor-less, current collector materials Cu@Cu31S16 cathodes, by in-situ etching of copper foil with a polysulfide precursor solution. The results indicate that Cu31S16 not only exhibits excellent stability and conductivity but also features rapid ion migration kinetics and low Zn2+ diffusion barriers.