Nucleation Radius Research Articles

The Effect of Process Parameters on the Pore Structure of Lotus-Type Porous Copper Fabricated via Continuous Casting

The pores in lotus-type porous copper are formed due to the difference in hydrogen solubility between the liquid and solid phases of copper. In a pressurized hydrogen atmosphere, hydrogen gas is released at the gas release and crystallization temperature, which is the melting point of copper. This study systematically analyzes the effects of process parameters, including hydrogen ratio, total pressure, and continuous casting speed, on the pore structure of lotus-type porous copper, with the aim of identifying the most critical process parameters for controlling pore diameter and density. Within the hydrogen ratio up to 50%, it was observed that as the hydrogen ratio increases, the pores tend to increase in porosity, and the pore diameter increases. As the hydrogen ratio increased from 25% to 50%, the pore diameter increased from 300 μm to 400 μm, while the pore density decreased from 3.3 N·mm−2 to 2.8 N·mm−2. As the total pressure increased, the pore diameter tended to decrease, and the pore density increased. Specifically, when the total pressure increased from 0.2 MPa to 0.4 MPa, the pore diameter decreased from 1100 μm to 400 μm, while the pore density increased significantly from 0.5 N·mm−2 to 2.8 N·mm−2. In addition, as the continuous casting speed increased, 30 to 90 mm·min−1, the pore diameter decreased from 850 μm to 400 μm, and the pore density increased from 0.7 N·mm−2 to 2.8. N·mm−2. Specifically, the increase in total pressure led to a decrease in Gibbs free energy and a reduction in the critical pore nucleation radius, which promoted pore formation and resulted in the creation of more, smaller pores. These results suggest that total pressure is the primary factor influencing both pore diameter and density in lotus-type porous copper.

A data-driven strategy for phase field nucleation modeling

We propose a data-driven strategy for parameter selection in phase field nucleation models using machine learning and apply it to oxide nucleation in Fe-Cr alloys. A grand potential-based phase field model, incorporating Langevin noise, is employed to simulate oxide nucleation and benchmarked against the Johnson-Mehl-Avrami-Kolmogorov model. Three independent parameters in the phase field simulations (Langevin noise strength, numerical grid discretization and critical nucleation radius) are identified as essential for accurately modeling the nucleation behavior. These parameters serve as input features for machine learning classification and regression models. The classification model categorizes nucleation behavior into three nucleation density regimes, preventing invalid nucleation attempts in simulations, while the regression model estimates the appropriate Langevin noise strength, significantly reducing the need for time-consuming trial-and-error simulations. This data-driven approach improves the efficiency of parameter selection in phase field models and provides a generalizable method for simulating nucleation-driven microstructural evolution processes in various materials.

Deposition and etching of (101)Zn facet exposed zinc electrode induced by trace COS achieving ultra-long cycle stability in zinc batteries

Rechargeable aqueous zinc-based batteries (RZBs) often suffer from poor cycling stability due to the instability of zinc deposition and etching processes. This work achieves dendrite-free zinc deposition with a smaller nucleation radius and rapid completion of the nucleation stage by a “triple regulation strategy” with trace chitosan oligosaccharide (COS) in ZnSO4 electrolyte (2 g L−1 COS). Theoretical and experimental results indicate that COS, with hydroxyl and amino functional groups, exhibits a high affinity for the (002)Zn and (100)Zn facets. Under the influence of a small amount of COS, the selective exposure of the (101)Zn facet is facilitated. The extensively exposed (101)Zn facet is protected by COS, which inhibits the occurrence of side reactions. Moreover, the presence of trace COS-02 changes the etching mode from three-dimensional (3D) to two-dimensional (2D), ensuring a uniform distribution of Zn2+ in the electric field during the deposition process. The unique 3D deposition and 2D etching mechanism induced by the COS additive result in exceptional cycling stability, exceeding 3800 h (1 mA cm−2) and 430 h (5 mA cm−2) in zinc symmetrical cells. Additionally, COS acts as a “molecular pillar” to stabilize VS2, enabling the Zn||VS2 full cell to achieve 1000 stable cycles with 89.6% capacity retention and an average coulombic efficiency of 99.95%. This work reveals a novel multiple regulation mechanism by using trace COS in RZBs, and provides a new approach for the development of long-term stable RZBs with preferential exposure facets.

Uncovering the combining V with Ni micro-addition alloying on the mechanical properties and multiphase transformation during solidification and homogenization of Al–Zn–Mg–Cu–Sc alloy

The ultimate tensile strength of the T6-aged Al–Zn–Mg–Cu–Sc alloy is improved by 24 MPa reached 667 MPa with the addition of 0.10 % V, 0.20 %Ni and decrease 0.1 %Sc. The thermodynamic and microalloying mechanisms of phase transformation during solidification and homogenization of Al–Zn–Mg–Cu–Sc–V–Ni alloy were clarified. The phase transformation model of Al3Sc (V, Ni) structure induced by V and Ni addition during homogenization was established. The calculation radius showed that coherent L12-ordered Al3Sc(V, Ni) nanoparticles were formed in the Al–Zn–Mg–Cu–Sc–V–Ni alloy, which had a small critical nucleation radius (22.0 nm). The large thermodynamic driving force and the high kinetic energy migration energy barrier of γ-Al7Cu4Ni and Al3Sc (V, Ni) phases led to the finer microstructure of grain. V element not only promoted the formation of Al21V2 phase containing Sc but also hindered the mutual diffusion of Al and (Sc, Ni) elements in the eutectic system via segregation at the α-Al/Al3Sc (V, Ni) interface, which improved the stability of the whole alloy. The edge nucleation of γ-Al7Cu4Ni phase upon its diffusion into a Sc-containing Al21V2 phase induced the formation of Al3Sc (V, Ni) structure, whereas the segregation of V and Ni further strengthened the alloy matrix.

Interfacial Zn2+-solvation regulator towards reversible and stable Zn anode

Aqueous zinc-ion batteries (AZIBs) are fundamentally challenged by the instability of the electrode/electrolyte interface, predominantly due to irreversible zinc (Zn) deposition and hydrogen evolution. Particularly, the intricate mechanisms behind the electrochemical discrepancies induced by interfacial Zn2+-solvation and deposition behavior demand comprehensive investigation. Organic molecules endowed with special functional groups (such as hydroxyl, carboxyl, etc.) have the potential to significantly optimize the solvation structure of Zn2+ and regulate the interfacial electric double layer (EDL). By increasing nucleation overpotential and decreasing interfacial free energy, these functional groups facilitate a lower critical nucleation radius, thereby forming an asymptotic nucleation model to promote uniform Zn deposition. Herein, this study presents a pioneering approach by introducing trace amounts of n-butanol as solvation regulators to engineer the homogenized Zn (H-Zn) anode with a uniform and dense structure. The interfacial reaction and structure evolution are explored by in/ex-situ experimental techniques, indicating that the H-Zn anode exhibits dendrite-free growth, no by-products, and weak hydrogen evolution, in sharp contrast to the bare Zn. Consequently, the H-Zn anode achieves a remarkable Zn utilization rate of approximately 20% and simultaneously sustains a prolonged cycle life exceeding 500 h. Moreover, the H-Zn//NH4V4O10 (NVO) full battery showcases exceptional cycle stability, retaining 95.04% capacity retention after 400 cycles at a large current density of 5 A g−1. This study enlightens solvation-regulated additives to develop Zn anode with superior utilization efficiency and extended operational lifespan.

Theoretical analysis of the initial nucleation characteristics of trace water vapor frosting on a cryogenic surface

In certain extreme conditions characterized by ultra-low water vapor content and ultra-low temperatures (e.g. cryogenic wind tunnel), trace water vapor frosting can also pose significant hazards. Considering the crucial role of initial nucleation on subsequent frosting processes, this study firstly investigated and compared the nucleation characteristics of frosting at different water vapor contents (0.1−1000 ppmv) from humid air to trace water vapor based on classical nucleation theory. The preferred nucleation phase diagrams and critical nucleation conditions were analyzed. Sensitivity of the nucleation mass transfer rate, as well as the frosting pathways were further identified. Results show that the nucleation characteristics of trace water vapor frosting (<100 ppmv) is significantly different from that of humid air frosting (>1000 ppmv). Trace water vapor frosting is more inclined towards desublimation nucleation due to its lower nucleation temperature and larger critical contact angle. The critical contact angles for 1000 ppmv, 100 ppmv and 0.1 ppmv are 49°, 75° and 120°, respectively. Furthermore, trace water vapor nucleation requires a greater subcooling degree, has a smaller critical nucleation radius, and is highly sensitive to surface contact angle and further-subcooling degree. At a surface contact angle of 120°, the nucleation subcooling degree of 0.1 ppmv is 2.9 K greater than that of 1000 ppmv. This study helps understanding the nucleation characteristics under different water vapor content conditions, which indicates that reducing subcooling degree and increasing contact angle are more effective anti-frosting methods than reducing water vapor content for trace water vapor frosting.

Research on the effect of different gas release conditions on the explosive boiling of overheated water containing NaCl

High-pressure storage tanks are widely used for transportation due to their convenience. However, sometimes the tanks themselves or the stored medium may become contaminated with impurities. NaCl is one of the most commonly encountered impurities. The pressure response curves of 1.0 mol/L NaCl solution and pure water within a 17L square stainless steel vertical storage tank are being investigated. The experimental results indicate that the pressure rebound is most pronounced when the medium inside the tank releases gas phase. Unlike pure water, NaCl solution still exhibits pressure rebound during pure liquid phase release. High-speed imaging reveals that the addition of NaCl impurities reduces the nucleation radius of bubbles, sharply increases their quantity, and exacerbates boiling phenomena. As the rupture area increases, the remaining liquid level of 1.0 mol/L NaCl is much lower compared to pure water. At the 70 % leakage position, the pressure recovery ratio of both liquids is the highest. After adding NaCl impurities, under all operating conditions, the pressure recovery ratio and pressure rise ratio exceed those observed under pure water conditions. This indicates that the presence of NaCl exacerbates the boiling of superheated liquids and increases the possibility of tank rupture.

Unveiling the nucleation and growth of Zr oxide precipitates in internally oxidized Nb3Sn superconductors

We report on atomic-scale analyses of nucleation and growth of Zr oxide precipitates and the microstructural evolution of internally oxidized Nb3Sn wires for high-field superconducting magnet applications, utilizing atom probe tomography (APT), transmission electron microscopy (TEM), and first-principles calculations. APT analyses reveal that oxygen and zirconium are already segregated at grain boundaries (GBs) in the unreacted Nb-1Zr-4Ta (at%) alloy prior to forming Nb3Sn through reacting the Nb alloy with Sn and SnO2. After forming Nb3Sn, Zr oxide precipitates nucleate both at the Nb3Sn/Nb heterophase interfaces and in the Nb3Sn grains, driven by the small solubilities of Zr and O in Nb3Sn compared to their value in Nb. A high number density (Nv) of Zr oxide nanoprecipitates is observed in the Nb3Sn layers, ∼1023 m−3, with a mean diameter <10 nm for a heat treatment at 625 °C. Quantitative APT and TEM analyses of the Zr oxide precipitates in the reacted Nb3Sn layers elucidate details of the nucleation, growth, and coarsening processes of the Zr oxide precipitates in Nb3Sn. First-principles calculations and classical nucleation theory are employed to study the nucleation of Zr oxide precipitates in Nb3Sn and to estimate the maximum energy barrier and critical radius for nucleation. Our research unveils the kinetic pathways for nucleation and growth of Zr oxide precipitates and the microstructural evolution of Nb3Sn layers, which helps to understand and improve the superconducting properties of internally oxidized Nb3Sn wires for use in high-field superconducting magnets.

Exploiting Non-Classical Nucleation for Improved Gas Bubble Mitigation on Nickel Electrocatalysts for the Oxygen Evolution Reaction

The efficient transport of gas poses a significant challenge in the design of high-performance gas evolving electrocatalysts. Inefficiencies due to mass transport limitations become more pronounced at the high current densities required in industrial electrolyzers, largely as a result of gas bubbles that obstruct a portion of the electrochemically active surface area of the anode and/or cathode, while also hindering electrolyte transport to the electrode surfaces. One promising approach to mitigate these sources of inefficiency is to engineer micro-to-nanoscale surface textures that promote the favorable growth and release of these bubbles. A range of structures have been shown to improve electrocatalyst performance under both stagnant and induced convection conditions, particularly in applications for hydrogen production via electrocatalytic water splitting in alkaline water electrolyzers.1 Trends between surface texture and electrocatalyst performance have been observed for a range of features, such as pillars,2,3 ridges,4 dimples,5 “cracked” structures,6 and electrodeposited crystalline structures,7 however substantial work is still needed to optimize the designs of these materials. These textured surfaces can influence bubble evolution in various ways, such as by altering the wetting properties of a surface, or by providing preferential nucleation sites. Previous studies have noted that surface structures that provide good control over bubble nucleation can often be adversely affected by increased bubble retention.3–5 The present study investigates a method of fabricating patterned electrocatalysts that provides a fine, tunable control over the distribution of bubble nucleation sites on the surfaces of planar Ni electrocatalysts for the oxygen evolution reaction (OER). These textured surfaces are designed to take advantage of so-called “non-classical nucleation” or “type IV nucleation”, a scenario in which gas is trapped at specific surface sites with an effective radius larger than the critical radius for classical nucleation, thereby allowing spontaneous bubble growth without being required to overcome an activation energy barrier.8 The separation between these sites on the surface of the OER active material (i.e., Ni) is then varied to obtain the most favorable distribution of these non-classical nucleation sites. Chronoamperometry is used to compare the current densities achieved by these patterned Ni electrodes to that of a planar Ni electrode. High speed videography is used to directly measure how these textures influence processes such as bubble growth and detachment, and to determine how these processes influence performance. A better understanding of these gas evolution processes can help lower the energy requirements for electrolyzers and may have more general implications for the design of energy efficient gas evolving electrocatalysts relevant to a variety of industrially important reactions.

Systematic First-Principles Investigations of the Nucleation, Growth, and Surface Properties of Al11RE3 Second-Phase Particles in Al-Based Alloys

At room temperature, Al alloys have excellent mechanical properties and are widely used in automotive, electronics, aerospace and other fields, but it is difficult to maintain this advantage in the middle and high temperature ranges. To address this issue, second-phase Al11RE3 (RE represents rare earth element) was introduced into a Al-Mg-RE alloy as its primary constituent. By incorporating RE elements as additives, this material exhibits exceptional mechanical and thermal properties at elevated temperatures. Based on first principles and quasi-harmonic approximation (QHA), the nucleation growth mechanism and surface properties of second-phase Al11RE3 were studied in this paper. The interfacial energy γα/β, strain energy ΔECS and chemical driving force ΔGV of Al11RE3 were obtained. Models1, 4, and 6 have better properties of para-site connections than inter-site connections. It is found that the resistances of particle nucleation, interface energy γα/β and strain energy ΔECS, first increase and then decrease with increased atomic number REs, but they are much smaller than the chemical driving force ΔGV. A reduced chemical driving force and a diminished nucleation radius R* are more favorable for the process of nucleation. The addition of Sc is the most unfavorable for nucleation, and La has the strongest nucleating ability, which gradually decreases as the atomic number of the lanthanide element increases. The nucleation ability of the Al11RE3 phase decreases with increasing temperature, which is consistent with the experiments. The nucleation radius R* also increases with increasing temperature, indicating that the nucleation ability decreases as the atomic number of the lanthanide elements increases. Since the smaller the nucleation radius R* the easier the nucleation, compared with model4 and 6, model1 has a smaller nucleation radius R* and the smallest increment. Thus, model1 is more prominent in the nucleation mechanism. In the particle growth study, the smaller the diffusion activation energy Q, the faster the diffusion rate in the Al matrix, and hence the higher the coiling rate, which promotes the growth of second-phase particles. The diffusion activation energy Q decreases sequentially from La to Ce and then increases with atomic number. The coarsening rate KLSW of the Al11RE3 phase in models1, 4, and 6 increased with increasing temperature, which promoted the growth of particles. This paper is intended to provide a solid theoretical basis for the production and application of aluminum alloy at high temperatures.

A single-bubble source for gravitational waves in a cosmological phase transition

Abstract We show that quantum fluctuations of an expanding phase transition bubble give rise to gravitational wave (GW) emission, even when considering a single bubble, without bubble collisions or plasma effects. The ratio of GW energy to the total bubble energy reservoir increases with time as ∝ t. If the bubble expands for long enough before percolation destroys it, back-reaction due to the GW emission becomes important after t br ~ (16π5)m pl 2 R 0 3, where R 0 is the bubble nucleation radius and m pl is the reduced Planck mass. As seen by experiments today, the GW energy spectrum would appear blue. However, simple estimates suggest that the signal falls short of detection by even ambitious future experiments.

Effect of cooling rate on solidification microstructure, microsegregation, and nanoprecipitates in medium carbon CrMo cast steel

Precipitation strengthening is a crucial method for enhancing the mechanical properties of steel. The bridgman directional solidification furnace, optical microscope (OM), scanning electron microscope (SEM), electron probe analyzer (EPMA) and transmission electron microscope (TEM) were used to investigate the effect of solidification cooling rate on the solidification microstructure, microsegregation, and nanoprecipitates in medium carbon CrMo cast steel. The results indicate that as the cooling rate increases, the solidification microstructure is significantly refined. The relationship between the cooling rate (CA) and primary dendrite arm spacing (PDAS, λ1) and secondary dendrite arm spacing (SDAS, λ2) are given by λ1 = 123.74 × C-0.4088A, λ2 = 66.63 × C-0.6532A. Solute elements like Cr, Mo, and V exhibit noticeable positive segregation in the inter-dendritic. When the cooling rate does not exceed 0.47 °C/s, the solute concentrations in the inter-dendritic increase with higher cooling rate, leading to a decrease in the effective solute partition coefficient. This phenomenon is primarily attributed to the back diffusion of solute elements during solidification. Following heat treatment, precipitation of M6C, V(C,N), and M23C6 occurs within the inter-dendritic regions. If the solidification cooling rate does not exceed 0.47 °C/s, the density and volume fraction of nanoprecipitates increase with higher cooling rate. This trend primarily results from the reduction in critical nucleation radius and critical nucleation energy, facilitating easier nucleation of nanoprecipitates.

Ultrasound induced grain refinement of crystallization in evaporative saline droplets

We investigate the effect of ultrasound on the evaporation and crystallization of sessile NaCl solution droplets which were positioned in traveling or standing wave ultrasound field. The experimental results indicated that the ultrasound field can significantly accelerate the evaporation rate of the sessile droplets and refine the crystal grains. By adjusting the distance between the sessile droplets and the ultrasound emitter, it is found that, in traveling wave ultrasound field, the sessile droplet evaporation time and the time for the appearance of NaCl grains exhibited a fluctuating increase as the droplet-emitter distance increased. While in the standing wave ultrasound, the sessile droplet evaporation rate increases with the increasing droplet-emitter distance. Overall, the traveling wave ultrasound field has a stronger effect on grain refinement of the sessile droplets than the standing wave ultrasound field. The grain refinement is attributed to the decrease of critical nucleation radius caused by ultrasound energy and the increase of the nucleation rate caused by the accelerated evaporation rate. In addition, the breakage of grains caused by ultrasonic cavitation would also lead to grain refinement.

Nucleation behaviors of p-coumaric acid in four solvents from induction time and metastable zone width: experiments and simulations

The study of nucleation behaviors during crystallization is important for understanding the drug crystallization process. The induction time of p-coumaric acid (p-CA) was measured in four solvents at various levels of supersaturation. The kinetic parameters of nucleation (interfacial energy, critical nucleation radius, and critical Gibbs free energy) were estimated using the classical nucleation theory (CNT). The results showed that the nucleation difficulty of p-CA in the four solvents was in the order of ethyl acetate > acetone > ethanol > methanol. In addition, the metastable zone width (MSZW) of p-CA was determined in four solvents. The nucleation behaviors of p-CA were further expounded using self-consistent Nývlt-like model and modified Sangwal’s model. The results were consistent with those of CNT. To further reveal the impact of interactions between solvent and solute molecules on the nucleation behaviors of p-CA, molecular electrostatic potential surfaces (MEPs), Hirshfeld Surfaces (HS), and the radial distribution function (RDF) were performed. The investigation revealed that the intensity of solvent–solute interactions depended primarily on the strength of hydrogen bonding interactions. The RDF results showed that the magnitude of hydrogen bonding interactions of p-CA in the four solvents was in the following order: ethyl acetate > acetone > ethanol > methanol. As the hydrogen bonding interactions between p-CA and solvent molecules became stronger, the dissociation of solute molecules from solvent molecules became more difficult, leading to a wider MSZW and a lower nucleation rate.

Ultrauniform Plating of Lithium on 10-nm-Scale Ordered Carbon Grids for Long Lifespan Lithium Metal Batteries.

Tailorable lithium (Li) nucleation and uniform early-stage plating is essential for long-lifespan Li metal batteries. Among factors influencing the early plating of Li anode, the substrate is critical, but a fine control of the substrate structure on a scale of ≈10nm has been rarely achieved. Herein, a carbon consisting of ordered grids is prepared, as a model to investigate the effect of substrate structure on the Li nucleation. In contrast to the individual spherical Li nuclei formed on the flat graphene, an ultrauniform and nuclei-free Li plating is obtained on the ordered carbon with a grid size smaller than the thermodynamical critical radius of Li nucleation (≈26nm). Simultaneously, an inorganic-rich solid-electrolyte-interphase is promoted by the cross-sectional carbon layers of such ordered grids which are exposed to the electrolyte. Consequently, the carbon grids with a grid size of ≈10nm show a favorable cycling stability for more than 1100 cycles measured at 2mA cm-2 in a half cell. With LiNi0.8Co0.1Mn0.1O2 as cathode, the assembled full cell with a cathode capacity of 3 mAh cm-2 and a negative/positive ratio of 1.67 demonstrates a stable cycling for over 130 cycles with a capacity retention of 88%.

Mathematical and computational models for simulating transient nuclear criticality excursions within plutonium nitrate systems

This paper presents a novel methodology for the analysis of transient nuclear criticality in aqueous solutions of plutonium nitrate. The transient methodology includes one-dimensional thermal hydraulics and a detailed description of radiolytic gas formation (including aqueous concentrations of radiolysis species and bubble population, nucleation radius and advection velocity). The positive temperature feedback effect in dilute plutonium solutions, due to a low lying resonance (at ≈ 0.3 eV) in the microscopic fission cross section, is investigated. The solutions’ nuclear properties, such as intrinsic neutron source and mean neutron generation time; thermophysical properties and heat transfer coefficients; linear energy transfer and dynamics of radiolytic gas nucleation; and subcritical power, are also investigated. The effect of step and ramp reactivity insertions on transient nuclear criticality behaviour is examined, alongside the effect of fuel solution ingress and egress from the system. For a solution containing 16.0 g L−1 plutonium with an acidity of 0.2 mol L−1, increasing the width of the prescribed step reactivity insertion from 2.25 to 2.50 s increased the magnitude of the initial power peak, and decreased the time to boil, by an order of magnitude. It was observed that the characteristics of the radiolytic gas were dependent on the magnitude of the initial power peak. For example, the transients with the highest initial power peak produced an initially large quantity of radiolytic gas, with defined oscillations in their quantity (and other properties) as the transient progressed. For transients with lower power peaks, the oscillations became less defined, with a reduced period and magnitude, due to the lower quantity of radiolytic gas produced due to the initial power peak. Many of the presented simulations of nuclear criticality transients were terminated when the solution started to boil, a phenomenon which is not included in the presented methodology. Boiling occurred when the initial reactivity input induced a power spike that raised the solution temperature enough for the positive reactivity feedback effect to sustain the transient even when the reactivity input was removed.

Efficient trapping of lithium-ions by branched amine for stable lithium metal anodes

Lithium metal batteries (LMBs) have attracted wide attention as high-energy–density energy storage devices, but their practical applications are hindered due to capacity degradation and safety concerns arising from the growth of lithium (Li) dendrites. The interaction between the electrode and Li, encompassing both Li-ions and Li metal, display significant potential for solving Li-dendrite issues in LMBs. Here, a novel strategy is reported to thin hybrid coating (∼1.3 μm) comprising highly polar poly(vinylidene fluoride) (PVDF) and branched poly(ethyleneimine) (PEI) onto Cu foil, employed as a current collector for the Li metal anode. The branched PEI contains amine group side chains that effectively capture Li ions, thereby facilitating rapid Li-ion transfer kinetics. Moreover, the inclusion of PEI enhances the surface energy of the polymer coating, leading to a reduction in the nucleation radius of Li and the promotion of uniform Li deposition. When coupled with a LiFePO4 (LFP) cathode, the Li-E40V@Cu||LFP full cell demonstrates an impressive initial capacity of 141.8 mA h g−1, which remains at 118.1 mA h g−1 after 518 cycles at 1C (1C = 170 mA h g−1). This investigation presents a novel approach to alleviate the formation of dendrites on Li metal anodes.

Heterogeneous nucleation of CO2 hydrate: A thermodynamics analysis considering effects of wall characteristics and solution activity

The massive emission of greenhouse gas CO2 has significant effects on global climate and environment, causing worldwide concern. It has been proposed to store CO2 in clathrate hydrates as a possible strategy for reducing atmospheric CO2 emission. Nevertheless, the CO2 hydrate formation rate is slow and its associated heterogeneous nucleation mechanisms are not well understood, which limit commercial applications of this technology. This study developed a thermodynamic model based on the change in availability function approach, considering effects of surface characteristics (including surface topography, roughness, curvature radius, and wettability), and CO2 dissolution on the solution's activity. The critical nucleation radius and energy barrier of CO2 hydrate nucleation are determined. Effects of pressure, temperature, wall characteristics and solution activity on the nucleation radius of CO2 hydrate are discussed. The results of this paper contribute to advancing carbon capture and storage technology based on hydrate methods.

Partial Ruptures Cannot Explain the Long Recurrence Intervals of Repeating Earthquakes

AbstractRepeating earthquakes repeatedly rupture the same fault asperities, which are likely loaded to failure by surrounding aseismic slip. However, repeaters occur less often than would be expected if these earthquakes accommodate all of the long‐term slip on the asperities. Here, we assess a possible explanation for this slip discrepancy: partial ruptures. On asperities that are much larger than the nucleation radius, a fraction of the slip could be accommodated by smaller ruptures on the same asperities. We search for partial ruptures of repeating earthquakes in Parkfield using the Northern California earthquakes catalog. We find 3991 individual repeaters which have 4468 partial ruptures. The presence of partial ruptures suggests that the asperities of repeating earthquakes are much larger than the nucleation radius. However, we find that partial ruptures could accommodate only around 25% of the slip on repeating earthquake patches. A 25% increase in the slip budget can explain only a small portion of the long recurrence intervals of repeating earthquakes.

Size-Independent Nucleation and Growth Model of Potassium Sulfate from Supersaturated Solution Produced by Stirred Crystallization.

This paper explores the kinetics of the crystallization of potassium sulfate in a stirred bed crystallizer through experimental investigation. Employing classical nucleation theory, the homogeneous and heterogeneous nucleation mechanisms of potassium sulfate were investigated. The induction time and critical nucleation parameters, including the surface tension (γ), critical nucleation radius (r*), critical nucleation free energy (ΔG*), and critical nucleation molecule number (i*), were meticulously determined under varying temperatures and supersaturation ratios. The experimental findings revealed that as the temperature and supersaturation ratio increased, the induction time, critical nucleation free energy, critical nucleation radius, and critical molecule number decreased whereas the nucleation rate increased. The crystalline shape remains relatively unaltered with respect to temperature and supersaturation ratio, yet the particle size (D10, D50, D90) increases as the supersaturation and temperature increase. The variations in the measured nucleation parameters align well with the predictions of classical nucleation theory. Furthermore, the kinetic equations of crystal nucleation and the growth rate in a stirred crystallization system were fitted using population balance equations. The results demonstrate that the growth rate increases with increasing supersaturation and stirring rates. Additionally, the effects of the parameters in the nucleation rate equation suggested that the suspension density exerted the greatest influence, followed by the supersaturation ratio and stirring rate. This extensive research provides invaluable theoretical guidance for optimizing the crystallization process and designing industrial crystallizers.