Structure Of Salt Research Articles

Crystal structure of the sodium salt of mesotrione: a triketone herbicide

The crystal structure of the sodium salt of mesotrione, namely, catena-poly[[sodium-μ3-2-[(4-methanesulfonyl-2-nitrophenyl)carbonyl]-3-oxocyclohex-1-en-1-olato] ethanol monosolvate], {[Na(C14H12NO7S)]C2H5OH} n , is described. The X-ray structural analysis results reveal that the coordination sphere is established by two chelating O atoms, the O atom of the coordinated ethanol molecule, and an O atom from the methylsulfonyl group of a neighboring molecule. Simultaneously, an O atom of the cyclohexane fragment serves as a bridge to a neighboring sodium ion, forming a flat Na–O–Na–O quadrangle, thereby forming a mono-periodic polymer. The structure displays O—H...O hydrogen bonds and C—H...O short contacts. Thermogravimetric analysis (TGA) data indicate that the sodium salt of mesotrione decomposes in four stages.

Mitigated Oxygen Loss in Lithium‐Rich Manganese‐Based Cathode Enabled by Strong Zr–O Affinity

AbstractOxygen loss is a serious problem of lithium‐rich layered oxide (LLO) cathodes, as the high capacity of LLO relies on reversible oxygen redox. Oxygen release can occur at the surface leading to the formation of spinel or rock salt structures. Also, the lattice oxygen will usually become unstable after long cycling, which remains a major roadblock in the application of LLO. Here, it is shown that Zr doping is an effective strategy to retain lattice oxygen in LLO due to the high affinity between Zr and O. A simple sol‐gel method is used to dope Zr4+ into the LLOs to adjust the local electronic structure and inhibit the diffusion of oxygen anions to the surface during cycling. Compared with untreated LLOs, LLO–Zr cathodes exhibit a higher cycling stability, with 94% capacity retention after 100 cycles at 0.4 C, up to 223 mAh g−1 at 1 C, and 88% capacity retention after 300 cycles. Theoretical calculations show that due to the strong Zr–O covalent bonding, the formation energy of oxygen vacancies has effectively increased and the loss of lattice oxygen under high voltage can be suppressed. This study provides a simple method for developing high‐capacity and cyclability Li‐rich cathode materials for lithium‐ion batteries.

Molecular dynamics simulations of the local structure and physicochemical properties of CaCl2 molten salt

Abstract CaCl2 molten salt, as a common electrolyte in the process of molten salt electrolysis, has a high decomposition potential and a strong ability to bind O2−. So the study of the structure and properties of CaCl2 is significant for the molten salt electrolysis. In this paper, molecular dynamics simulations (MD) method was used to investigate the variation rule of the local structure and physicochemical properties of CaCl2 molten salt with temperature. The results show that the temperature has less effect on the heterozygous ion pairs and more effect on the homozygous ion pair. With the increase of temperature, the interaction between ion pairs is weakened, the coordination number decreases, the local structure changes a little, and the structural configuration tends to be an irregular octahedral structure with vacancies. The calculated self-diffusion coefficients, viscosities, and ionic conductivities are consistent well with the reality, but there is a significant error in densities due to the strong polarization effect of Ca2+ compared to the reality. The local structure directly determines the thermodynamic properties of the molten salts. This study promotes the basic theoretical research on alkaline earth metal-containing molten salts and is an important reference for the study of molten salt electrolysis process.

A reactive force field approach to modeling corrosion of NiCr alloys in molten FLiNaK salts

The interface between NiCr alloys and FLiNaK molten salt exhibits complex corrosion behavior, mainly driven by intricate chemical interactions involving Cr and F−ions. Understanding these dynamic reactions is crucial for developing effective corrosion mitigation strategies to ensure the long-term durability of Ni-based alloy components in molten salt technologies. However, obtaining molecular-level understanding through experiments is challenging. To address this, we utilize reactive molecular dynamics simulations enabled by a reactive force field, ReaxFF, to investigate detailed reaction dynamics at the atomic level. We first present the development of the ReaxFF parameter set for Ni/Cr/F/Li/Na/K based on extensive first-principles calculations. With this force field, we achieve a strong agreement for the structure of FLiNaK molten salt by comparing the pair distribution functions with experimental and simulation results. Furthermore, our simulations successfully reproduce the experimental phenomenon of Cr dissolution in fluoride salt, with the corrosion rate depending on the alloy and salt compositions. Particularly, our simulations reveal that increasing the concentration of Li can enhance the formation of a compact double layer, mitigating Cr dissolution. This work enables a fundamental understanding of the interfacial behavior between fluoride salt and NiCr alloys.

Interfacial Electrochemical Lithiation and Dissolution Mechanisms at a Sulfurized Polyacrylonitrile Cathode Surface.

Advances in sulfurized-polyacrylonitrile (SPAN)-based cathode materials promise safer and more efficient lithium-sulfur (Li-S) battery performance. To elucidate electrolyte-cathode interfacial electrochemistry and polysulfide (PS) dissolution, we emulate discharge SPAN reactions via ab initio molecular dynamics (AIMD) simulations. Plausible structures and their lithiation profiles are cross-validated via Raman/IR spectroscopy and density functional theory (DFT). Lithium bis(fluorosulfonyl)imide (LiFSI) plays versatile roles in the Li-SPAN cell electrochemistry, primarily as the major source in forming the cathode-electrolyte interphase (CEI), further verified via X-ray photoelectron spectroscopy and AIMD. Besides being a charge carrier and CEI composer, LiFSI mediates the PS generation processes in SPAN electrochemical lithiation. Analysis of AIMD trajectories during progressive lithiation reveals that, compared to carbonates, ether solvents enable stronger solvation and chemical stabilization for both salt and SPAN structures. Differentiated CEI formation and electrochemical lithiation decomposition pathways and products are profoundly associated with the intrinsic nature of lithium bonding with oxygen and sulfur.

Stratigraphic evolution of a salt-walled basin: the influence of diapirism and compressional tectonics on the sedimentary record of the Estopanyà syncline (South-Central Pyrenees)

This contribution describes the influence of diapirism and compressional tectonics in the sedimentary record of the Estopanyà and Boix synclines (salt-walled basins) in the South-Central Pyrenees (NE Spain). Based on mapping and logging of five stratigraphic sections, two lithostratigraphic units (LU-1 and 2) along the eastern diapir margin of these synclines and five more (LU-3 to 7) in their inner parts are defined. LU-1 and 2 consist of monomictic breccias deposited probably during the Upper Triassic-Oligocene and the Upper Cretaceous, respectively. LU-3 to 7 constitute a marine to fluvial succession of the Tremp Group deposited during the Upper Cretaceous to Paleocene. The stratigraphic and sedimentological record indicates that the topography, position, and accommodation space of the Estopanyà and Boix synclines was actively controlled by the evolution of salt structures from the Late Cretaceous to the Oligocene in response to the advance of the Alpine compression in the South-Central Pyrenees. The growth of salt-inflated ridges with a near parallel orientation to the axis of the studied synclines since the Upper Cretaceous, progressively compartmentalized the Boix syncline until inhibiting sedimentation during the lower Paleocene. In the upper Paleocene, the Alpine compression approached the study area increasing salt evacuation and the subsidence of the Estopanyà and Boix synclines. During the early to middle Ypresian, onset of compression led to salt expulsion by piercing the sedimentary roof of the inherited salt-inflated ridges and forming two salt walls at the eastern margin of the Estopanyà and Boix synclines that were squeezed and welded (possibly through secondary welds) due to tectonic compression during the Oligocene. This contribution provides a new interpretation of the structural and stratigraphic evolution of the Estopanyà and Boix synclines, proposing an evolutionary model that includes the rejuvenation, growth, and extrusion of salt walls as deciphered from the stratigraphy, sedimentology, and petrology of the diapir margin breccias and the sedimentary succession of the adjoining salt-embedded basins. Hence, it provides a new analogue study for understanding the interplay between compressional tectonics, diapirism, and sedimentation to other inverted salt basins with precursor salt walls worldwide.

Complex Structure of Molten FLiBe (2 LiF – BeF 2 ) Examined by Experimental Neutron Scattering, X-Ray Scattering, and Deep-Neural-Network Based Molecular Dynamics

The use of molten salts as coolants, fuels, and tritium breeding blankets in the next generation of fission and fusion nuclear reactors benefits from furthering the characterization of the molecular structure of molten halide salts, paving the way to predictive capability of the chemical and thermophysical properties of molten salts. Due to its neutronic, chemical, and thermochemical properties, 2LiF-BeF2 is a candidate molten salt for several fusion- and fission-reactor designs. We performed neutron and x-ray total-scattering measurements to determine the atomic structure of liquid 2LiF-BeF2. We also performed and neural-network molecular-dynamics simulations to predict the structure obtained by neutron- and x-ray-diffraction experiments. The use of machine learning provides improvements to the efficiency in predicting the structure at a longer length scales than is achievable with simulations at significantly lower computational expense while retaining near accuracy. We found that the NNMD simulations accurately predicted the BeF42− oligomer formations seen in the experimental first-structure-factor peak. Our combination of high-resolution measurements with large-scale molecular dynamics provided an avenue to explore and experimentally verify the intermediate-range ordering beyond the first-nearest neighbor that has posed too many experimental and computational challenges in previous works. With a deeper understanding of the salt structure and ion ordering, the evolution of salt chemistry over the lifetime of a reactor can be better predicted, which is crucial to the licensing and operation of advanced fission and fusion reactors that employ molten salts. To this end, this work will serve as a reference for future studies of salt structure and macroscopic properties with and without the addition of solutes. Published by the American Physical Society 2024

Versatile separation layer for separation and purification of ethanol/cyclohexane mixtures by pervaporation process

Quaternized cyclodextrin (CD) obtained by quaternization reaction of bromine-CD and N, N-Dimethylethylenediamine, are used for preparing PV membranes. Three different kinds of composite membranes are interfacially synthesized on the polyacrylonitrile substrate. The different sequences of piperazine and quaternized CD reacted with trimesoyl trichloride show a great difference in separation of polar/nonpolar mixture. The topmost layer of CD-based polyamide layer shows a higher separation factor, which can be inferred that quaternized CD played the major role during separation. Quaternized CD can integrate cavity size, polar and non-polar characteristics to achieve exceptional screening performance. PV performance of the optimal membrane at 25 °C is measured using the 5 wt% ethanol and cyclohexane mixture, exhibiting the separation factor of 66.7. PV performances of other different organic mixtures prove that nonpolar inner cavity of CD has a stronger inclusion of cyclohexane than other smaller nonpolar molecules, thus enhancing the repulsion of cyclohexane from the mixture. In summary, these outside polar quaternary ammonium salt structures of quaternized CD have a high selectivity for polar solvents. The nonpolar cavity of CD shows the inclusion ability of nonpolar solvents, especially the organic solvent with large molecular volume, which hinders their penetration and improves the separation factor.

Influence of preexisting structures on salt structures in the Kuqa Depression, Tarim Basin, Western China: Insights from seismic data and numerical simulations

AbstractThe preexisting structures that developed in the basement and subsalt strata play a key role in the salt structural deformation in the Kuqa Depression, Tarim Basin. The characteristics of preexisting structures and their controls on the salt structure are investigated via the latest three‐dimensional seismic data and numerical modelling. The results show that the preexisting structures that developed in the Kuqa Depression mainly consist of basement faults, palaeouplifts, subsalt slopes and early passive salt diapirs. Basement faults are mainly distributed in the Kelasu and Qiulitag structural belts and control the position of development and deformation style of the Miocene compressive salt structure. The differences in styles and reactivation degrees of basement faults lead to great diversity in the salt structure. The palaeouplifts mainly include the Wensu, western Qiulitag, Xinhe and Yaha‐Luntai palaeouplifts. The original sedimentary range and later deformation space of the salt layer are limited by the palaeouplift, resulting in strong salt thrusting in the Awate sag in the western part of the Kuqa Depression. The heterogeneous spatial distribution of the palaeouplift promoted the development of regional strike‐slip transform belts. Subsalt slopes are located mainly on the northern edge of the western Qiulitag low uplift and block the southward flow of the salt, causing the salt to form salt domes; the size of these domes is closely related to the subsalt slope. Early passive salt diapirs mainly developed in the Quele and Bozidun areas of the western Kuqa Depression, and they were preferentially active during the compression period, inducing the formation of a piercement salt nappe. Numerical modelling revealed that the preexisting structure strongly controlled the stress–strain distribution during the deformation of the salt structure. The spatial distribution heterogeneity of the basement structure is an important factor in the structural zonation along the north–south strike and segmentation along the west–east strike in the Kuqa Depression, as well as an important inducer of the piercement salt structure.

Impact of Salt Tectonics on Temperatures Distribution Revealed by RSCM Thermometry in the SW Alps (France)

Evaporites have a strong impact on the structural and sedimentary evolution of sedimentary basins and fold-and-thrust belts. They also have a thermal conductivity that can be more important than other sedimentary rocks and are thus able to modify the thermal history of these sedimentary basins and fold-and-thrust belts. Even though this property is known and has been of interest for the oil and gas industry, no field examples have been studied trying to decipher how salt rock impacts temperature distribution in fold-and-thrust belts. In this paper, we use the Raman Spectroscopy on Carbonaceous Material (RSCM) to track the record of the peak thermal event around three salt structures from the southern sub-Alpine fold-and-thrust belt in SE France. These three salt structures are (1) the Astoin allochthonous salt sheet and the associated overturned megaflap, (2) the Rocher de Hongrie and (3) the Daluis diapir. Our results show that the resulting record of peak temperatures around the structures is different depending on the type of salt structure and its kinematic. The Astoin structure shows that salt tectonics during the Jurassic-Cretaceous has impacted the temperature distribution around the allochthonous salt sheet while at Daluis and the Rocher de Hongrie, the temperatures have overprinted an already existing salt-related structure. The impact of the salt structure on temperature distribution is always local but the interpretation of the RSCM temperatures may systematically be difficult without considering early salt tectonics in the structural evolution of the area.

Preparation, and antibacterial activity of chitosan derivative containing double quaternary ammonium salt and hydantoin structures

Chitosan quaternary ammonium salt antibacterial agents with a single structure have the drawbacks of slow bactericidal speed and poor bactericidal effect, which cannot meet the practical usage requirements. To address the problem, in this study, we designed and synthesized a novel chitosan derivative containing double quaternary ammonium salt and chloride hydantoin structures (QCS-CA-DEADH-Cl) by using chitosan, 5,5-dimethyl hydantoin, methyl iodide, and 2-Dimethylaminoethyl chloride hydrochloride as the main raw materials, and then used as antibacterial agent. The structure of QCS-CA-DEADH-Cl was characterized by Fourier transform infrared spectra, X-ray photoelectron spectroscopy, Thermogravimetric, and Scanning electron microscopy. The antibacterial activity of QCS-CA-DEADH-Cl, and the renewability and stability of N-Cl structure in QCS-CA-DEADH-Cl were explored. The results indicated that the N-Cl structure of QCS-CA-DEADH-Cl has strong renewability and storage stability. Moreover, the synergistic effect of quaternary ammonium salt structure and N-Cl structure endowed QCS-CA-DEADH-Cl with excellent antibacterial activity. This work does not only provide a new perspective for the preparation of novel chitosan antibacterial agents but also contributes to expanding the comprehensive utilization of biomass resources.

Crystal structures of potassium and cesium salts of adenine: the role of alkali cations.

This study reports the crystal structures of potassium and cesium salts of adenine (K-adenine and Cs-adenine) in perspective of the interaction of alkali cations with purine nucleobases. Unlike previously-known guanine...

A viscosity-sensitive probe based on the structure of indole salt

Long-lasting and high-intensity fluorescence imaging of tumor cells.

Synthesizing new Bi-structure energetic coordination compounds using ternary components

[Ag(1-APZ-5-HCA)(ClO4)2]n (ECPs-1) has a dual structure of ionic salt and coordination compounds. It also has the advantages of high ClO4− content and oxygen balance, acceptable mechanical stimulation and excellent explosion performance.

Compositional transferability of deep potential in molten LiF-BeF2 and LaF3 mixtures: prediction of density, viscosity, and local structure.

The accumulation of lanthanide fission products carries the risk of altering the structure and properties of the nuclear fuel carrier salt LiF-BeF2 (Flibe), thereby downgrading the operating efficiency and safety of the molten salt reactor. However, the condition-limited experimental measurements, spatiotemporal-limited first-principles calculations, and accuracy-limited classical dynamic simulations are unable to capture the precise local structure and reliable thermophysical properties of heterogeneous molten salts. Therefore, the deep potential (DP) of LaF3 and Flibe molten mixtures is developed here, and DP molecular dynamics simulations are performed to systemically study the densities, diffusion coefficients, viscosities, radial distribution functions and coordination numbers of multiple molten Flibe + xLaF3, the quantitative relationships between these properties and LaF3 concentration are investigated, and the potential structure-property relationships are analyzed. Eventually, the transferability of DP on molten Flibe + LaF3 with different formulations as well as the predictability of structures and properties are achieved at the nanometer spatial scale and the nanosecond timescale.

Spectroscopic and thermodynamic characterization of a cobalt-verdazyl valence tautomeric system. influence of crystal structure, solvent and counterion.

Crystallization of the verdazyl-based valence tautomeric ion [Co(dipyvd)2]2+ (where dipyvd is the radical ligand 1-isopropyl-3,5-di(2'-pyridyl)-6-oxoverdazyl) with a variety of different counterions results in materials that show varying degrees of valence tautomeric (VT) transition in the solid state. The X-ray structure of the SbF6 salt at 150 K reveals a localized structure for the S = 1/2 tautomer, with a Co3+ cation and distinct anionic and radical ligands. Comparison with the structure of the same material at 300 K reveals large structural changes in the ligand as a result of the valence tautomeric equilibrium. Data for the S = 3/2 form is less conclusive; X-ray spectroscopy on the PF6 salt suggests a degree of low spin Co2+ character for the S = 3/2 tautomer at very low temperature though this is inconsistent with EPR data at similar temperatures and structural information at 150 K. Magnetic measurements on the [BArF4]- and triflate salts in organic solvents show that the VT equilibrium is dependent on solvent and ion pairing effects.

Carboxylate ester-based electrolytes for Na-ion batteries.

Sodium-ion batteries (SIBs) is a promising technology for next-generation energy storage. However, their performance is limited at low temperatures due to the inferior bulk and interfacial resistance of current electrolytes. Here we present a systematic study to evaluate carboxylate ester-based electrolytes for SIB applications, due to their favorable properties (i.e., low melting point, low viscosity and high dielectric constant). The effects of salt, concentration and solvent molecular structure were systematically examined and compared with those of carbonate-based electrolytes. By combining electrochemical tests with spectroscopic characterization, the performance of selective carboxylate ester-based electrolytes in hard carbon/Na and Na3V2(PO4)3/Na half-cells was evaluated. We found carboxylates enable high electrolyte conductivities, especially at low temperatures. However, carboxylates alone are inadequate to form a stable interphase due to their high reactivity, which can be addressed by choosing a suitable anion and facilitating anion-rich Na+ solvation by increasing salt concentration. Fundamental knowledge on the chemistry-property-performance correlation of this new family of electrolytes was obtained, and their benefits and pitfalls were thoroughly discussed. These discoveries and knowledge will shed light on the potential of carboxylate ester-based electrolytes and provide the foundation for further electrolyte engineering.

Formation of compounds with diverse polyelectrolyte morphologies and nonlinear ion conductance in a two-dimensional nanofluidic channel.

Aqueous electrolytes subjected to angstrom-scale confinement have recently attracted increasing interest because of their distinctive structural and transport properties, as well as their promising applicability in bioinspired nanofluidic iontronics and ion batteries. Here, we performed microsecond-scale molecular dynamics simulations, which provided evidence of nonlinear ionic conductance under an external lateral electric field due to the self-assembly of cations and anions with diverse polyelectrolyte morphologies (e.g., extremely large ion clusters) in aqueous solutions within angstrom-scale slits. Specifically, we found that the cations and anions of Li2SO4 and CaSO4 formed chain-like polyelectrolyte structures, whereas those of Na2SO4 and MgSO4 predominantly formed a monolayer of hydrated salt. Additionally, the cations and anions of K2SO4 assembled into a hexagonal anhydrous ionic crystal. These ion-dependent diverse polyelectrolyte morphologies stemmed from the enhanced Coulomb interactions, weakened hydration and steric constraints within the angstrom-scale slits. More importantly, once the monolayer hydrated salt or ionic crystal structure was formed, the field-induced ion current exhibited an intriguing gating effect at a low field strength. This abnormal ion transport was attributed to the concerted movement of cations and anions within the solid polyelectrolytes, leading to the suppression of ion currents. When the electric field exceeded a critical strength, however, the ion current surged rapidly due to the dissolution of many cations and anions within a few nanoseconds in the aqueous solution.

Geological Storage Conditions and Potential Analysis of Carbon Dioxide in the High-steep Fold Belt in Eastern Sichuan Basin

Carbon sequestration refers to the technology of capturing carbon and storing it safely instead of directly discharging CO2 into the atmosphere. Rock salt is a promising CO2 reservoir, and the underground rock salt structure formed by salt cavern reservoirs in geological history has a natural sealing function. Storing carbon dioxide in salt caves can ensure that carbon dioxide is stably stored underground for a long time. However, at present, there are few studies on carbon sequestration in abandoned salt caves. This study analyses the characteristics of carbonate-evaporite strata in the high fold zone of eastern Sichuan and qualitatively evaluates Triassic carbonate-evaporite layers formed in the depth range of 800-3000 m in various sedimentary basins in Chongqing. A large set of carbonates-evaporites are developed in Chongqing, and the carbonate rocks near evaporites have low porosity and permeability, which can be used as CO2 storage caprock in salt cavities. Thick evaporated strata can also provide a good cover for CO2 storage in abandoned salt caves, which has great potential space resources.

Contrasting Styles of Salt‐Tectonic Processes in the Ionian Zone (Greece and Albania): Integrating Surface Geology, Subsurface Data, and Experimental Models

AbstractThe Ionian Zone (IZ) is one of the key elements of the fold and thrust belt (FTB) of the Albanian and Hellenides orogen and contains large outcrops of Triassic evaporites. The IZ consists of various thrust sheets with a general westward vergence, stacking over the Apulian and Pre‐Apulian zones, and repeating a thick carbonate sequence of Upper Triassic to Eocene age. Thrusting becomes younger toward the west with a piggyback sequence, starting during the latest Oligocene Epoch in the Internal Ionian and ending in the Pliocene in the External Ionian. We have studied the IZ in southern Albania and northwestern Greece using field observations and borehole data and by fully interpreting a recently acquired 2D seismic data set. Our objectives are to establish the geometry and nature of the contacts associated with the major Triassic outcrops, to unravel precursor salt diapirs, and to assess their role during the Alpine contraction. Salt structures include gentle salt pillows, isolated salt plugs and diapirs, thrust welds, and salt walls. Combining these observations with experimental modeling results, we show how these structures control the geometry and kinematics of the Alpine thrusts or the location and kinematics of recent strike‐slip faults. Salt minibasins have also been identified, demonstrating salt mobility conditioned Mesozoic sedimentation in the Ionian Basin. The use of salt‐tectonics principles to evaluate the structural style and evolution of the IZ FTB also opens new directions for interpreting the subsurface structure and evolution of the region.