Search Results (832)

Molecular dynamics (MD) simulations have been performed on the energetics, mechanical properties, and irradiation response of seventy-three 3C-SiC symmetric tilt grain boundaries (STGBs) with three tilt axes (<100>, <110> and <111>). The effect of GB characteristics on the STGB properties has been investigated. The GB energy is positively and linearly correlated with the excess volume, but the linearity in SiC is not as good as in metals, which stems from the inhomogeneous structural relaxation near GBs induced by orientation-sensitive covalent bonding. For <110>STGBs, the shear strength exhibits symmetry with respect to the misorientation angle of 90°, which is consistent with ab initio calculations for Al in similar shear orientations. Cascades are performed with 8 keV silicon as the primary knock-on atom (PKA). No direct correlation is found between the sink efficiency of GBs for defects and GB characteristics, which comes from the complexity of the diatomic system during the recovery phase. For GBs with smaller values of Σ, the GBs exhibit a weaker blocking effect on the penetration of irradiated defects, resulting in a lower number of defects in GBs and a higher number of total surviving defects. In particular, it is seen that the percentage decrease in tensile strength after irradiation is positively correlated with the Σ value. Taken together, these results help to elucidate the impact of GB behavior on the mechanical properties of as well as the primary irradiation damage in SiC and provide a reference for creating improved materials through GB engineering. Full article

Classical thermodynamics omits rigidity, which property distinguishes solids from gases and liquids. By accounting for rigidity (i.e., Young’s elastic modulus, ϒ), we recently amended historical formulae and moreover linked heat capacity, thermal expansivity, and ϒ. Further exploration is motivation by the importance of classical thermodynamics to various applied sciences. Based on heat performing work, we show here, theoretically, that density times sublimation enthalpy divided by the molar mass (ρΔH_sub/M, energy per volume), depends linearly on ϒ (1 GPa = 10⁹ J m⁻³). Data on diverse metals, non-metallic elements, chalcogenides, simple oxides, alkali halides, and fluorides with cubic structures validate this relationship at ambient conditions. Furthermore, data on hcp metals and molecular solids show that ρΔH_sub/M is proportional to ϒ for anisotropic materials. Proportionality constants vary only from 0.1 to 0.7 among these different material types (>100 substances), which shows that the elastic energy reservoir of solids is large. Proportionality constants depend on whether molecules or atoms are sublimated and are somewhat affected by structure. We show that ductility of refractory, high-ϒ metals affect high-temperature determinations of their ΔH_sub. Our results provide information on sublimation processes and subsequent gas phase reactions, while showing that elasticity of solids is the key parameter needed to assessing their energetics. Implications are highlighted. Full article

With the rapid growth of energy demand, the development of efficient energy-conversion technologies (e.g., water splitting, fuel cells, metal-air batteries, etc.) becomes an important way to circumvent the problems of fossil fuel depletion and environmental pollution, which motivates the pursuit of high-performance electrocatalysts with controllable compositions and morphologies. Among them, two-dimensional (2D) Pt-group metallic electrocatalysts show a series of distinctive architectural merits, including a high surface-to-volume ratio, numerous unsaturated metal atoms, an ameliorative electronic structure, and abundant electron/ion transfers channels, thus holding great potential in realizing good selectivity, rapid kinetics, and high efficiency for various energy-conversion devices. Considering that great progress on this topic has been made in recent years, here we present a panoramic review of recent advancements in 2D Pt-group metallic nanocrystals, which covers diverse synthetic methods, structural analysis, and their applications as electrode catalysts for various energy-conversion technologies. At the end, the paper also outlines the research challenges and future opportunities in this emerging area. Full article

In order to design new materials at atomic-length scales, there is a need to connect the fractal nature of fracture surfaces at the atomic scale using quantum mechanics modeling with that of the experimental data of fracture surfaces at macroscopic-length scales. We use a semi-empirical quantum mechanics simulation of fracture in amorphous silica to calculate a parameter identified as a critical characteristic length, $a_0$, which has been experimentally derived from the fractal nature of fracture for many materials that fail in a brittle matter. To our knowledge, there are no known simulation models other than our related research that use the fractal parameter $a_0$ to describe the fractal fracture of the fracture surface using quantum mechanical simulations. We provide evidence that $a_0$ can be calculated at both the atomic and macroscopic scale, making it a fundamental property of the structure and one of the elements of fractal fracture. We use a continuous random network model and reaction coordinate method to simulate fracture. We propose that fracture in amorphous silica occurs due to bond reconfiguration resulting in increased strain volume at the crack tip. We hypothesize two specific configurations leading to fracture from a four-fold ring reconfiguration to three-fold ring or (newly observed) five-fold ring configurations resulting in a change in volume. Finally, we define a reconfiguration fracture energy at the atomic level, which is approximately the value of the experimental fracture surface energy. Full article

This study investigates the development of silver (Ag)-doped zirconia (ZrO₂) coatings deposited on 316LVM stainless steel via the unbalanced magnetron sputtering technique. The oxygen content in the Ar/O₂ gas mixture was systematically varied (12.5%, 25%, 37.5%, and 50%) to assess its influence on the resulting coating properties. In response to the growing demand for biomedical implants with improved durability and biocompatibility, the objective was to develop coatings that enhance both wear and corrosion resistance in physiological environments. The effects of silver incorporation and oxygen concentration on the structural, tribological, and electrochemical behavior of the coatings were systematically analyzed. X-ray diffraction (XRD) was employed to identify crystalline phases, while atomic force microscopy (AFM) was used to characterize surface topography prior to wear testing. Wear resistance was evaluated using a ball-on-plane tribometer under simulated prosthetic motion, applying a 5 N load with a bone pin as the counter body. Corrosion resistance was assessed through electrochemical impedance spectroscopy (EIS) in a physiological solution. Additionally, tribocorrosive performance was investigated by coupling tribological and electrochemical tests in Ringer’s lactate solution, simulating dynamic in vivo contact conditions. The results demonstrate that Ag doping, combined with increased oxygen content in the sputtering atmosphere, significantly improves both wear and corrosion resistance. Notably, the ZrO₂-Ag coating deposited with 50% O₂ exhibited the lowest wear volume (0.086 mm³) and a minimum coefficient of friction (0.0043) under a 5 N load. This same coating also displayed superior electrochemical performance, with the highest charge transfer resistance (38.83 kΩ·cm²) and the lowest corrosion current density (3.32 × 10⁻⁸ A/cm²). These findings confirm the high structural integrity and outstanding tribocorrosive behavior of the coating, highlighting its potential for application in biomedical implant technology. Full article

The one-dimensional (1D) Sb(III)-based organic–inorganic hybrid perovskite (AImd)₂¹_∞[SbI₅] (AImd = 1-allylimidazolium) crystallizes in the orthorhombic, centrosymmetric space group Pnma. The structure consists of corner-sharing [SbI₆] octahedra forming 1D chains separated by allylimidazolium cations. Void analysis through Mercury CSD software confirmed a densely packed lattice with a calculated void volume of 1.1%. Integrated quantum theory of atoms in molecules (QTAIM) and non-covalent interactions index (NCI) analyses showed that C–H···I interactions between the cations and the ¹_∞[SbI₅]²⁻ network predominantly stabilize the supramolecular assembly followed by N–H···I hydrogen bonds. The calculated growth morphology (GM) model fits very well to the experimental morphology. UV–Vis diffuse reflectance spectroscopy allowed us to determine the optical band gap to 3.15 eV. Density functional theory (DFT) calculations employing the B3LYP, CAM-B3LYP, and PBE0 functionals were benchmarked against experimental data. CAM-B3LYP best reproduced Sb–I bond lengths, while PBE0 more accurately captured the HOMO–LUMO gap and the associated electronic descriptors. These results support the assignment of an inorganic-to-organic [Sb–I] → π* charge-transfer excitation, and clarify how structural dimensionality and cation identity shape the material’s optoelectronic properties. Full article

Under the trend of lightweight and high-efficiency development in industrial equipment, precise regulation of lubrication in gear reducers is a key breakthrough for enhancing transmission system efficiency and reliability. This study establishes a three-dimensional numerical model for high-speed gear jet lubrication using computational fluid dynamics (CFD) and dynamic mesh technology. By implementing the volume of fluid (VOF) multiphase flow model and the standard k-ω turbulence model, the study simulates the dynamic distribution of lubricant in gear meshing zones and analyzes critical parameters such as the oil volume fraction, eddy viscosity, and turbulent kinetic energy. The results show that reducing the oil injection distance significantly enhances lubricant coverage and continuity: as the injection distance increases from 4.8 mm to 24 mm, the lubricant shifts from discrete droplets to a dense wedge-shaped film, mitigating lubrication failure risks from secondary atomization and energy loss. The optimized injection distance also improves the spatial stability of eddy viscosity and suppresses excessive dissipation of turbulent kinetic energy, enhancing both the shear-load capacity and thermal management. Dynamic data from monitoring point P show that reducing the injection distance stabilizes lubricant velocity and promotes more consistent oil film formation and heat transfer. Through multiphysics simulations and parametric analysis, this study elucidates the interaction between geometric parameters and hydrodynamic behaviors in jet lubrication systems. The findings provide quantitative evaluation methods for structural optimization and energy control in gear lubrication systems, offering theoretical insights for thermal management and reliability enhancement in high-speed transmission. These results contribute to the lightweight design and sustainable development of industrial equipment. Full article

To address the technical problems of broad droplet size spectrum, insufficient atomization uniformity, and spray drift in plant protection unmanned aerial vehicle (UAV) applications, this study developed a novel two-stage aerial electrostatic spraying device based on the coupled mechanisms of hydraulic atomization and electrostatic induction, and, through the integration of three-dimensional numerical simulation and additive manufacturing technology, a new two-stage inductive charging device was designed on the basis of the traditional hydrodynamic nozzle structure, and a synergistic optimization study of the charging effect and atomization characteristics was carried out systematically. With the help of a charge ratio detection system and Malvern laser particle sizer, spray pressure (0.25–0.35 MPa), charging voltage (0–16 kV), and spray height (100–1000 mm) were selected as the key parameters, and the interaction mechanism of each parameter on the droplet charge ratio (C/m) and the particle size distribution (Dv50) was analyzed through the Box–Behnken response surface experimental design. The experimental data showed that when the charge voltage was increased to 12 kV, the droplet charge-to-mass ratio reached a peak value of 1.62 mC/kg (p < 0.01), which was 83.6% higher than that of the base condition; the concentration of the particle size distribution of the charged droplets was significantly improved; charged droplets exhibited a 23.6% reduction in Dv50 (p < 0.05) within the 0–200 mm core atomization zone below the nozzle, with the coefficient of variation of volume median diameter decreasing from 28.4% to 16.7%. This study confirms that the two-stage induction structure can effectively break through the charge saturation threshold of traditional electrostatic spraying, which provides a theoretical basis and technical support for the optimal design of electrostatic spraying systems for plant protection UAVs. This technology holds broad application prospects in agricultural settings such as orchards and farmlands. It can significantly enhance the targeted deposition efficiency of pesticides, reducing drift losses and chemical usage, thereby enabling agricultural enterprises to achieve practical economic benefits, including reduced operational costs, improved pest control efficacy, and minimized environmental pollution, while generating environmental benefits. Full article

In this study, the effects of B2-NiAl phase volume fractions (2–50%) on the mechanical properties and deformation mechanism of dual-phase FeNiAl alloys were systematically investigated by molecular dynamics simulation. A two-phase alloy atomic model with different B2 phase volume fractions was constructed. The simulation results show that when the volume fraction of the B2 phase is 3%, the alloy exhibits the best comprehensive mechanical properties. The strengthening is mainly due to the back stress field effect induced by the B2 phase. However, when the content of the B2 phase exceeds 5%, it will cause grain boundary stress concentration, resulting in a sharp decrease in the ductility of the alloy. Atomic-scale simulation analysis further reveals that low B2 content (3%) maintains grain boundary stability by inhibiting grain rotation, regulating superdislocation pairs and inverse boundary slip modes. This study provides a theoretical basis for the design of dual-phase alloys, reveals the cooperation mechanism of B2 and FCC, and has guiding significance for the development of high-strength and toughness Fe-based alloys. Full article

As an innovative plant protection method in precision agriculture, electrostatic spray technology can increase the droplet coverage area by over 30% coMpared to conventional spraying. This technology not only achieves higher droplet deposition density and coverage but also enables water and pesticide savings while reducing environmental pollution. This study, combining theoretical analysis with experimental validation, reveals the critical role of electrode material selection in induction-based electrostatic spray systems. Theoretical analysis indicates that the Fermi level and work function of electrode materials fundamentally determine charge transfer efficiency, while corrosion resistance emerges as a key parameter affecting system durability. To elucidate the effects of different electrode materials on droplet charging, a coMparative study was conducted on nickel, copper, and brass electrodes in both pristine and moderately corroded states based on the corrosion classification standard, using a targeted mesh-based charge-to-mass measurement device. The results demonstrated that the nickel electrode achieved a peak charge-to-mass ratio of 1.92 mC/kg at 10 kV, which was 8.5% and 11.6% higher than copper (1.77 mC/kg) and brass (1.72 mC/kg), respectively. After corrosion, nickel exhibited the smallest reduction in the charge-to-mass ratio (19.2%), significantly outperforming copper (40.2%) and brass (21.6%). Droplet size analysis using a Malvern Panalytical Spraytec spray particle analyzer (measurement range: 0.1–2000 µm) further confirmed the atomization advantages of nickel electrodes. The volume median diameter (Dv50) of droplets produced by nickel was 4.2–8 μm and 6.8–12.3 um smaller than those from copper and brass electrodes, respectively. After corrosion, nickel showed a smaller increase in droplet size spectrum inhomogeneity (24.5%), which was lower than copper (30.4%) and brass (25.8%), indicating superior droplet uniformity. By establishing a multi-factor predictive model for spray droplet size after electrode corrosion, this study quantifies the correlation between electrode characteristics and spray performance metrics. It provides a theoretical basis for designing weather-resistant electrostatic spray systems suitable for agricultural pesticide application scenarios involving prolonged exposure to corrosive chemicals. This work offers significant technical support for sustainable crop protection strategies. Full article

Next-generation recycling technologies must be urgently innovated to tackle huge volumes of spent batteries, photovoltaic panels or printed circuit boards (WPCBs). Current e-waste recycling industrial technology is dominated by traditional recycling technologies. Herein, ionic liquids (ILs), deep eutectic solvents (DESs) and promising oxidizing additives that can overcome some traditional recycling methods of metal ions from e-waste, used in our works from last year, are presented. The unique chemical environments of ILs and DESs, with the application of low-temperature extraction procedures, are important environmental aspects known as “Green Methods”. A closed-loop system for recycling zinc and manganese from the “black mass” (BM) of waste, Zn-MnO₂ batteries, is presented. The leaching process achieves a high efficiency and distribution ratio using the composition of two solvents (Cyanex 272 + diethyl phosphite (DPh)) for Zn(II) extraction. High extraction efficiency with 100% zinc and manganese recovery is also achieved using DESs (cholinum chloride/lactic acid, 1:2, DES 1, and cholinum chloride/malonic acid, 1:1, DES 2). New, greener recycling approaches to metal extraction from the BM of spent Li-ion batteries are presented with ILs ([N_8,8,8,1][Cl], (Aliquat 336), [P_6,6,6,14][Cl], [P_6,6,6,14][SCN] and [Benzet][TCM]) eight DESs, Cyanex 272 and D2EHPA. A high extraction efficiency of Li(I) (41–92 wt%) and Ni(II) (37–52 wt%) using (Cyanex 272 + DPh) is obtained. The recovery of Ni(II) and Cd(II) from the BM of spent Ni-Cd batteries is also demonstrated. The extraction efficiency of DES 1 and DES 2, contrary to ILs ([P_6,6,6,14][Cl] and [P_6,6,6,14][SCN]), is at the level of 30 wt% for Ni(II) and 100 wt% for Cd(II). In this mini-review, the option to use ILs, DESs and Cyanex 272 for the recovery of valuable metals from end-of-life WPCBs is presented. Next-generation recycling technologies, in contrast to the extraction of metals from acidic leachate preceded by thermal pre-treatment or from solid material only after thermal pre-treatment, have been developed with ILs and DESs using the ABS method, as well as Cyanex 272 (only after the thermal pre-treatment of WPCBs), with a process efficiency of 60–100 wt%. In this process, four new ILs are used: didecyldimethylammonium propionate, [N_10,10,1,1][C₂H₅COO], didecylmethylammonium hydrogen sulphate, [N_10,10,1,H][HSO₄], didecyldimethylammonium dihydrogen phosphate, [N_10,10,1,1][H₂PO₄], and tetrabutylphosphonium dihydrogen phosphate, [P_4,4,4,4][H₂PO₄]. The extraction of Cu(II), Ag(I) and other metals such as Al(III), Fe(II) and Zn(II) from solid WPCBs is demonstrated. Various additives are used during the extraction processes. The Analyst 800 atomic absorption spectrometer (FAAS) is used for the determination of metal content in the solid BM. The ICP-OES method is used for metal analysis. The obtained results describe the possible application of ILs and DESs as environmental media for upcycling spent electronic wastes. Full article

Epoxy-based composite materials, widely used in various industries such as coatings, adhesives, aerospace, electronics, and biomedical engineering, remain a topic of global interest due to their varying characteristics based on the base resin and curing agents used. This paper employs molecular dynamics simulation to examine the thermal and mechanical properties, as well as molecular behaviors, of epoxy systems cured with diglycidyl ether of bisphenol F as the base resin and aromatic amine curing agents, specifically the meta structure of 3,3′-diaminodiphenyl sulfone (3,3′-DDS) and the para structure of 4,4′-diaminodiphenyl sulfone (4,4′-DDS). The 3,3′-DDS system demonstrated a greater density and Young’s modulus than the 4,4′-DDS system. This tendency was analyzed based on differences in molecular fractional free volume and cohesive energy density (CED). The 4,4′-DDS system exhibits a higher glass transition temperature (T_g) compared to the 3,3′-DDS system, with values of 406.36 K and 431.22 K, respectively. To understand this behavior, we examined atomic-scale displacements at T_g through mean squared displacement analysis, which revealed that the onset of molecular motion occurs at a lower temperature in the 3,3′-DDS system. Molecular-level study reveals how the structural features of each curing agent appear in thermal and mechanical properties, offering important insights for epoxy system development. Full article

The synthesis and characterization of two novel redox-active MOFs/CPs based on 3d transition metal ions and 3,6-ditriazolyl-2,5-dihydroxybenzoquinone (trz₂An) are reported herein. By combining trz₂An with Ni^II and Mn^II ions via the hydrothermal method, two phases, formulated as [Ni₂(trz₂An)₂]·2.5H₂O (1) and [Mn(trz₂An)(H₂O)]·1.5H₂O (2), are obtained. Both compounds crystallize as neutral polymeric 3D frameworks, where the metal ions are coordinated through the oxygen atoms of the anilate linkers forming either straight (1) or zig-zag (2) 1D chains. In particular, (1) is a MOF, where these chains are connected through the nitrogen atom at the 4 position of the triazolyl group, which completes the coordination sphere of each metal ion, affording a 3D structure containing a void volume of 28.7% and voids that can be useful for the sorption of small molecules. Interestingly, (1) and (2) show a redox behavior due to the presence of the anilate linker, being reduced electrochemically in the −0.7 to −0.9 V range due to the benzoquinone–semiquinone one-electron reduction and magnetic behavior dominated by antiferromagnetic interactions in the anilate 1D chains. Full article

The atomization performance of methanol fuel plays a crucial role in enhancing methanol engine efficiency, contributing to the decarbonization of the shipping industry. The droplet microscopic characteristics of methanol spray were experimentally investigated using a single-hole direct injection injector in a constant volume chamber. The particle image analysis (PIA) system equipped with a slicer was employed for droplet detecting at a series of measurement positions in both the dense spray region and dilute spray region, then the spatial distributions of droplet size and velocity were examined. Key findings reveal distinct atomization behaviors between dense and dilute spray regions. Along the centerline, the methanol spray exhibited poor atomization, characterized by a high concentration of aggregated droplets, interconnected liquid structures, and large liquid masses. In contrast, the spray periphery demonstrated effective atomization, with only well-dispersed individual droplets observed. Droplet size distribution analysis showed a sharp decrease from the dense region to the dilute region near the nozzle. In the spray midbody, droplet diameter initially decreased significantly within the dense spray zone, stabilized in the transition zone, and then exhibited a slight increase in the dilute region—though remaining smaller than values observed at the central axis. Velocity measurements indicated a consistent decline in the axial velocity component due to air drag. In contrast, the radial velocity component displayed irregular variations, attributed to vortex-induced flow interactions. These experimentally observed droplet behaviors provide critical insights for refining spray models and enhancing computational simulations of methanol injection processes. Full article

We report on the results of investigations of atomic layer deposited (ALD) amorphous alumina (Al₂O₃) coatings for the protection of limestone with a wide range of porosity against acid-based dissolution. The protective effects of the ALD coatings were investigated by aqueous acid immersion. The solution pH was tracked over time for a constant volume of acetic acid solution with an initial pH of 4 with the stone samples immersed. We find the protective effect of ALD alumina coatings is extremely promising, with 90 nm thick coatings slowing the initial and total rate of substrate mass loss significantly by up to two orders of magnitude. The eventual failure of the ALD coatings during immersion was also investigated. Pitted areas on the substrate were discovered and were found to have an area fraction that correlates to the changing pH of the acid solution during immersion. The variation of the protective action of the films with thickness is consistent with kinetics, which are limited by diffusion within the pits rather than through the films. Our findings point to the dominant role of defects in the coatings in their eventual failure. We also show that the appearance of the stone does not change significantly for the thickest and most protective ALD films, making the treatment promising for cultural heritage applications. Full article