Stable Liquid Phase Research Articles

Deep Eutectic Solvents as Electrolytes for Zn Batteries: Between Blocked Crystallization, Electrochemical Performance and Corrosion Issues.

Deep eutectic solvents (DESs) are an emerging class of ionic liquids with high tunability and promise for battery applications. In this study, we investigated acetamide-based DESs for Zn batteries, focusing on a synergistic mixture of two known acetamide (Ace)-based DESs: Ace4ZnCl2and Ace4ZnTFSI2. By combining these two DESs in various ratios, we aimed to enhance ionic conductivity and optimize electrochemical performance while addressing corrosion concerns. The resulting ternary mixtures exhibit superior ionic mobility, with the highest conductivity observed for Ace4(ZnTFSI2)0.85(ZnCl2)0.15, which balances performance and stability. However, increased ionic mobility introduces crystallization challenges, limiting liquid-phase stability. Despite these challenges, the optimized DES mixture demonstrates excellent cycling performance with reduced overpotentials and acceptable corrosion levels, offering a viable pathway for scalable Zn battery applications.

Green pathways for biomass transformation: A holistic evaluation of deep eutectic solvents (DESs) through life cycle and techno-economic assessment

The utilization of renewable biomass resources to manufacture biofuels, chemicals, and materials has garnered considerable attention. Deep eutectic solvents (DESs) have surfaced as a promising instrument within the realm of biomass conversion, owing to their distinctive attributes such as biodegradability, negligible toxicity, easier fabrication, liquid-phase stability and renewability as opposed to ionic liquids (ILs). Research into DESs, particularly those derived from natural sources, is expanding to advance affordable and sustainable biomass conversion. However, the bottlenecks of DES are its limited solubility for certain biomass constituents, cost and availability. To overcome these hurdles, ongoing research and technological innovations strive to tap into the complete potential of DESs in biomass conversion. This review underscores the importance of evaluating DESs' eco-friendly potential comprehensively, encompassing ecological, financial, and technological standpoints which aims to illuminate how DESs can effectively contribute to sustainable biomass utilization, fostering an environmentally conscious circular bio-based economy.

Cloud point and oxidation stability analysis of turpentine oil and ethanol in b40 biodiesel blend using response surface methodology

Abstract Given the availability and the potential of bioresources as blending components of diesel blends, the synergy of turpentine oil and ethanol in the B40 biodiesel blend is presented in this work. Response surface methodology (RSM) was employed to study the influence of both bioresources on the important characteristics of B40 biodiesel blends, i.e., cloud point and oxidation stability. Based on the result, the relationship between turpentine oil and ethanol on cloud point was best expressed with a two-factor interaction (2FI) model. Meanwhile, the quadratic model was more suitable for oxidation stability The most ideal cloud point was found at 10.6 °C in 8% v/v and 0.5% v/v of turpentine oil and ethanol concentration, respectively and the most ideal oxidation induction time was found at 250 minutes in 5% v/v and 0.7% v/v of turpentine oil and ethanol, respectively. It is believed that the rigid structure of turpentine oil is responsible for preventing crystal formation and the ethanol-biodiesel blend attraction also enhances their liquid-phase stability. Furthermore, the oxidation stability of B40 biodiesel blends continues to be maintained at sufficient levels.

Changes in Microscale Liquid Formation in Lump and Sinter Mixed Burden Softening and Melting Tests with the Addition of Hydrogen

With the movement toward hydrogen-enriched blast furnace operation to lower greenhouse gas emissions, ferrous burden design must be reconsidered to optimize furnace permeability. Increasing the ratio of direct charge lump ore in the ferrous burden also presents an opportunity to lessen the emissions associated with the production of sinter and pellets. Under traditional blast furnace conditions, lump ore usage is improved by mixing it with the sinter in the burden to promote their favorable high-temperature interactions (both chemical and physical). As such, mechanistic changes to the interaction must be understood to optimize burden design, including for future operations with hydrogen addition. In this study, liquid formation in both the metallic and oxide components of ferrous burdens is microscopically investigated. Oxide liquid and solid phase stability at the interfaces of dissimilar burdens are visualized using a novel mapping technique, and metallic iron is etched to reveal microstructures indicative of carbon. Results indicate that the inclusion of hydrogen promotes the gas carburization of metallic iron in sinter, but not lump. It was concluded that mixed burden softening and melting performance with hydrogen addition were improved through the addition of lump in two ways: the highly metallic lump particles provide structural support for the collapsing sinter bed and also suppress the formation of early liquid slag from the sinter.Graphical

Complex oiling-out behavior of procaine with stable and metastable liquid phases.

During the crystallization of a solute from solvent(s), spontaneous liquid-liquid phase separation (LLPS) might occur, under certain conditions. This phenomenon, colloquially referred to as "oiling-out" in the pharmaceutical industry, often leads to undesired outcomes, including undesired particle properties, encrustation, ineffective impurity rejection, and excessively long process time. Therefore, it is critical to understand the thermodynamic driving force and phase boundaries of this phenomenon, such that rational strategies can be developed to avoid oiling-out or minimize its negative impact. In this study, we systematically evaluated the oiling-out behavior of procaine, a low melting point drug, in the solvent systems heptane, and ethanol-heptane as a function of temperature and solvent composition. In the procaine-heptane binary system, we observed a region where the LLPS is metastable with respect to crystallization, which is most commonly observed in the crystallization of modern active pharmaceutical ingredients (APIs); however, we also identified a region of the phase diagram where the LLPS is stable with respect to crystallization, and therefore will persist indefinitely. In the procaine-ethanol-heptane ternary system we identified five different regions, including a homogeneous liquid (L) region, two solid-liquid (SLI and SLII) regions, a liquid-liquid (LILII) region, and a solid-liquid-liquid (SLILII) region. The binary and ternary phase diagrams were also predicted using a state-of-the-art thermodynamic model: the SAFT-γ-Mie equation of state, and the results were compared with experimental data. Our findings highlight the complexity of oiling-out behavior. This work also represents a combined modeling and experimental platform to identify phase boundaries that will enable rational selection of strategies to crystallize active pharmaceutical ingredients with oiling-out risks.

Quantifying the Ejecta Thickness From Large Complex Craters on (1) Ceres

AbstractQuantifying the ejecta thickness distribution from complex craters is key to understanding surface‐evolving processes on Ceres. Using the Park et al. (2019, https://doi.org/10.1016/j.icarus.2018.10.024) shape model, we estimated the ejecta thickness of five complex craters located in Ceres' equatorial region by analyzing 1,778 smaller, simple craters in their continuous ejecta deposits. In addition, we constrained their rim‐crest ejecta thickness following Sharpton (2014, https://doi.org/10.1002/2013JE004523). The ejecta thicknesses range from ∼3 to 73 m and ∼96–223 m around complex craters and at their rim crest localities, respectively. We find that ejecta thicknesses on Ceres are thinner than those on the Moon. Meltwater likely facilitates thin ejecta deposits on Ceres, given that fluid pressure conditions allow transient liquid water stability at shallow depths (∼1.8 m). Such water must be short‐lived because the atmospheric pressure on Ceres is too low (≳2.09 × 10−8 Pa) to allow a stable liquid phase. Our findings are consistent with previous work that ascribes fluidized appearing ejecta morphologies to the melting of subsurface water ice.

Stable pair liquid phase in fermionic systems

We predict the existence of a pair-liquid phase in lattice fermion systems with finite-range attractive interactions. This exotic state competes on one side with a normal Fermi liquid of unpaired fermions and on the other side with a phase-separated state where all fermions are coupled into macroscopic clusters. We show that such a phase is absent in bosonic systems and therefore is protected by the exclusion principle. In contrast with zero-range attractive systems where clustering of more than two fermions is directly prohibited, here quantum statistics acts dynamically and in a more subtle way. Since a many-fermion wave function must have nodes, the cluster formation threshold is larger than the pair formation threshold. By directly solving a four-body Schroedinger equation on one- and two-dimensional lattices, we map the boundaries of pair stability. The pair liquid phase should be observable in cold atom systems. We also discuss implications for the preformed-pair mechanism of high-temperature superconductivity.

Phytosterols and γ-Oryzanol as Cholesterol Solid Phase Modifiers during Digestion.

Literature reports that ingestion of phytosterols and γ-oryzanol contributes to cholesterol lowering. Despite in vivo observations, thermodynamic phase equilibria could explain phenomena occurring during digestion leading to such effects. To advance the observations made by previous literature, this study was aimed at describing the complete solid-liquid phase equilibrium diagrams of cholesterol + phytosterol and γ-oryzanol systems by DSC, evaluating them by powder X-ray, microscopy, and thermodynamic modeling. Additionally, this study evaluated the phenomena observed by an in vitro digestibility method. Results confirmed the formation of solid solution in the cholesterol + phytosterols system at any concentration and that cholesterol + γ-oryzanol mixtures formed stable liquid crystalline phases with a significant melting temperature depression. The in vitro protocol supported the idea that the same phenomena can occur during digestion in which mechanochemical forces were probably the mechanisms promoting cholesterol solid phase changes in the presence of such phytocompounds. In this case, these changes could alter cholesterol solubility and possibly its absorption in the gastrointestinal lumen.

Circuit-Based Design of Microfluidic Drop Networks

Microfluidic-drop networks consist of several stable drops—interconnected through microfluidic channels—in which organ models can be cultured long-term. Drop networks feature a versatile configuration and an air–liquid interface (ALI). This ALI provides ample oxygenation, rapid liquid turnover, passive degassing, and liquid-phase stability through capillary pressure. Mathematical modeling, e.g., by using computational fluid dynamics (CFD), is a powerful tool to design drop-based microfluidic devices and to optimize their operation. Although CFD is the most rigorous technique to model flow, it falls short in terms of computational efficiency. Alternatively, the hydraulic–electric analogy is an efficient “first-pass” method to explore the design and operation parameter space of microfluidic-drop networks. However, there are no direct electric analogs to a drop, due to the nonlinear nature of the capillary pressure of the ALI. Here, we present a circuit-based model of hanging- and standing-drop compartments. We show a phase diagram describing the nonlinearity of the capillary pressure of a hanging drop. This diagram explains how to experimentally ensure drop stability. We present a methodology to find flow rates and pressures within drop networks. Finally, we review several applications, where the method, outlined in this paper, was instrumental in optimizing design and operation.

Supramolecular meso-Trick: Ambidextrous Mirror Symmetry Breaking in a Liquid Crystalline Network with Tetragonal Symmetry.

Bicontinuous and multicontinuous network phases are among nature's most complex structures in soft matter systems. Here, a chiral bicontinuous tetragonal phase is reported as a new stable liquid crystalline intermediate phase at the transition between two cubic phases, the achiral double gyroid and the chiral triple network cubic phase with an I23 space group, both formed by dynamic networks of helices. The mirror symmetry of the double gyroid, representing a meso-structure of two enantiomorphic networks, is broken at the transition to this tetragonal phase by retaining uniform helicity only along one network while losing it along the other one. This leads to a conglomerate of enantiomorphic tetragonal space groups, P41212 and P43212. Phase structures and chirality were analyzed by small-angle X-ray scattering (SAXS), grazing-incidence small-angle X-ray scattering (GISAXS), resonant soft X-ray scattering (RSoXS) at the carbon K-edge, and model-dependent SAXS/RSoXS simulation. Our findings not only lead to a new bicontinuous network-type three-dimensional mesophase but also reveal a mechanism of mirror symmetry breaking in soft matter by partial meso-structure racemization at the transition from enantiophilic to enantiophobic interhelical self-assembly.

Thermophysical properties of the TiAl-2Cr-2Nb alloy in the liquid phase measured with an electromagnetic levitation device on board the International Space Station, ISS-EML

Abstract Thermophysical properties of the γ-TiAl alloy Ti-48Al-2Cr-2Ni in the liquid phase were investigated with a containerless electromagnetic processing device on board the International Space Station. Containerless processing is warranted by the high liquidus temperature T liq = 1 776 K and the high dissolution reactivity in the liquid phase. Thermophysical properties investigated include the surface tension and viscosity, density, specific heat capacity and the electrical resistivity. The experiments were supported by magnetohydrodynamic fluid flow calculations. The Ti-48Al-2Cr-2Ni alloy could be stably processed over extended times in the stable and undercooled liquid phase and exhibited an exceptional degree of undercooling before solidification. Experimental processes and thermophysical properties so obtained will be described. The experiments demonstrate the broad experimental capabilities of the electromagnetic processing facility on the International Space Station for thermophysical investigations in the liquid phase of metallic alloys not achievable by other methods.

Wetting behavior of a colloidal particle trapped at a composite liquid-vapor interface of a binary liquid mixture.

A partially miscible binary liquid mixture, composed of A and B particles, is considered theoretically under conditions for which a stable A-rich liquid phase is in thermal equilibrium with the vapor phase. The B-rich liquid is metastable. The liquids and the thermodynamic conditions are chosen such that the interface between the A-rich liquid and the vapor contains an intervening wetting film of the B-rich phase. In order to obtain information about the large-scale fluid structure around a colloidal particle, which is trapped at such a composite liquid-vapor interface, three related and linked wetting phenomena at planar liquid-vapor, wall-liquid, and wall-vapor interfaces are studied analytically, using classical density functional theory in conjunction with the sharp-kink approximation for the number density profiles of the A and B particles. If in accordance with the so-called mixing rule the strength of the A-B interaction is given by the geometric mean of the strengths of the A-A and the B-B interactions, and similarly the ratio between the wall-A and the wall-B interaction, the scenario, in which the colloid is enclosed by a film of the B-rich liquid, can be excluded. Up to six distinct wetting scenarios are possible, if the above mixing rules for the fluid-wall and for the fluid-fluid interactions are relaxed. The way the space of system parameters is divided into domains corresponding to the six scenarios, and which of the domains actually appear, depends on the signs of the deviations from the mixing rule prescriptions. Relevant domains, corresponding, e.g., to the scenario in which the colloid is enclosed by a film of the B-rich liquid, emerge, if the ratio between the strengths of the wall-A and the wall-B interactions is reduced as compared to the mixing rule prescription, or if the strength of the A-B interaction is increased to values above the one from the mixing rule prescription. The range, within which the contact angle may vary inside the various domains, is also studied.

Phase Behavior and Polymorphism of Saturated and Unsaturated Phytosterol Esters.

This study investigated how the physicochemical characteristics of phytosterol esters are influenced by the chain length and degree of unsaturation of the fatty acid ester moiety. Saturated and unsaturated phytosterol esters (PEs) were synthesized by the esterification of different types of fatty acids (stearic, palmitic, lauric, oleic, and linoleic acid) to β-sitosterol. The non-isothermal crystallization and melting behavior of the pure PEs were analyzed. It was proven by X-ray diffraction that saturated β-sitosteryl esters and β-sitosteryl oleate formed a bilayer crystal structure. The lamellar spacings of the bilayer structure decreased with decreasing fatty acid chain length and with an increasing degree in unsaturation. The degree of unsaturation of the fatty acid chain of the β-sitosteryl esters also influenced the type of subcell packing of the fatty acid moieties in the bilayer structure, whether or not a metastable or stable liquid crystalline phase was formed during cooling. Furthermore, it was found that the melting temperature and enthalpy of the β-sitosteryl esters increased with an increasing fatty acid chain length while they decreased with an increasing degree of unsaturation. The microscopic analyses demonstrated that β-sitosteryl oleate formed much smaller spherulites than their saturated β-sitosteryl analogues.

Evolution of phases and their thermal stability in Ge–Sn nanofilms: a comprehensive in situ TEM investigation

The group IV Ge–Sn system is a promising candidate for a variety of electronic and photonic applications due to its tunable bandgap and compatibility with Si-based technology. However, the peculiarities of the components interaction, phases evolution and, especially, their thermal stability are still far from a brimming comprehension. In the course of in situ TEM heating experiments, we demonstrate the high potential of using nanosized, layered Sn/amorphous-Ge films for the synthesis of Ge–Sn solid solutions with an enhanced Sn content. Particularly, we observe the formation of highly uniform, diamond structured Ge1-xSnx solid solution with Sn content of 33 at% by metal-induced crystallization (MIC) at 90 °C. The Ge0.67Sn0.33 alloy is stable in the range of 20–150 °C, whereat additional heating leads to partial Sn segregation and subsequent melting of the Sn-rich phase. The formation of the metastable and stable Sn-rich liquid phases, which was observed at 90 and 150–190 °C, respectively, has a key role in the system thermal stability. The temperatures and the observed complex interphase interactions are discussed in the frame of the size effects in nanoscaled structures.

Arylazopyrazoles for Long-Term Thermal Energy Storage and Optically Triggered Heat Release below 0 °C.

Arylazopyrazole derivatives based on four core structures (4pzMe, 3pzH, 4pzH, and 4pzH-F2) and functionalized with a dodecanoate group were demonstrated to store thermal energy in their metastable Z isomer liquid phase and release the energy by optically triggered crystallization at -30 °C for the first time. Three heat storage-release schemes were discovered involving different activation methods (optical, thermal, or combined) for generating liquid-state Z isomers capable of storing thermal energy. Visible light irradiation induced the selective crystallization of the liquid phase via Z-to-E isomerization, and the latent heat stored in the liquid Z isomers was preserved for longer than 2 weeks unless optically triggered. Up to 92 kJ/mol of thermal energy was stored in the compounds, demonstrating remarkable thermal stability of Z isomers at high temperatures and liquid-phase stability at temperatures below 0 °C.

A new liquid-phase method and its comparison to two solid-phase microbial respiration activity methods to assess organic waste stability

Goal of the work was to compare the respiration activities, as measured via oxygen consumption with three different organic waste stability methods so that to propose the optimal one. The novelty of the work is that there exists no comparison of solid-phase with liquid-phase stability assessment techniques in the literature. The respiration activities were assessed using two solid-phase methods and a manometric liquid-phase method (MANLIQ) performed on twenty-seven organic substrates. The methods rely on measuring oxygen consumption (uptake) via pressure drops (liquid-phase test, static solid-phase test) or via direct O2 measurements on the gaseous phases at the inlet and outlet of the respirometer (solid-phase dynamic test). A positive statistically significant correlation was calculated between the MANLIQ and the static solid-phase indices. The maximum rate MANLIQ index for the raw substrates was 2900 mg O2 kg−1 VS h−1, while most of the processed substrates had cumulative MANLIQ indices below 160 g O2 kg−1 VS. The ratio of the liquid indices to the static solid-phase indices ranged from 1.6 to 2.7 and the ratio of the liquid indices to the dynamic solid-phase indices ranged from 0.2 to 0.4. The MANLIQ method failed to result in a good correlation of the processing time with the respiration indices. On the other hand, a correlation was more visible in the two solid-phase tests, despite the large variability of the types and sources of the substrates. Therefore, the solid-phase methods should be preferred over the liquid-phase method to assess stability for various organic substrates.

Field-induced quantum spin liquid in the Kitaev-Heisenberg model and its relation to α−RuCl3

Recently considerable excitement has arisen due to the experimental observation of a field-induced spin liquid phase in the compound $\alpha$-RuCl$_3$. However, the nature of this putative spin liquid phase and the relevant microscopic model Hamiltonian remain still unclear. In this work, we address these questions by performing large-scale numerical simulations of a generalized Kitaev-Heisenberg model proposed to describe the physics of $\alpha$-RuCl$_3$. While there is no evidence for an intermediate phase for in-plane magnetic fields, our results strongly suggest that a stable intermediate spin liquid phase, sandwiched between a magnetically ordered phase at low fields and a high-field polarized phase, can be induced by out-of-plane magnetic fields. Moreover, we show that this field-induced spin liquid phase can be smoothly connected to a spin liquid possessing a spinon Fermi surface as proposed recently for the Kitaev model. The relevance of our results to $\alpha$-RuCl$_3$ is also discussed.

System size effect on crystal nuclei morphology in supercooled metallic melt

We present a molecular dynamics (MD) study of size effect on the crystal nuclei geometry, formation and growth in supercooled tantalum film. The process is studied in a set of MD trajectories that are obtained by ultrafast cooling from the stable liquid phase to the temperature below the glass transition temperature. We describe the nucleation process by two morphological parameters. Along with the nucleus size, we analyze the asphericity that is a measure of deviation of crystal nuclei from idealized spherical form. This method allows to demonstrate that there are two paths for crystal nucleus shape and size evolution. The first path is crystal growth through high asphericity values. We show that this is caused by coalescence of the crystals. This mechanism is not affected by the size of the system. The second path is formation of long-lived crystal clusters that do not lead to the crystallization of the whole system on the MD simulation timescale. We demonstrate that such clusters have common geometric features which strongly depend on the system size.

Solid-Like Ordering of Imidazolium-Based Ionic Liquids at Rough Nanostructured Oxidized Silicon Surfaces.

The investigation of ionic liquids (ILs) confined in a solid porous matrix is of particular interest considering that these substances are increasingly used as an electrolyte in devices employing nanostructured nanoporous materials for the electrodes. Furthermore, the confinement of the ILs into a porous matrix would allow overcoming the difficulties of their packaging, leakage, and portability. In order to support the applications, a deeper understanding of the interaction of ILs with the nanoporous solid material and its increased interface is required. In this work, we report on the modification of morphological and mechanical properties of the imidazolium-based [Bmim][NTf2] IL upon surface spatial confinement on a cluster-assembled, nanostructured, rough, oxidized silicon (ns-SiOx) surface. An atomic force microscopy investigation revealed that upon the interaction with the ns-SiOx film, [Bmim][NTf2] locally rearranges into ordered, layered, stiff, and poorly conducting solid-like domains, coexisting with, and embedded into, the liquid IL film. The observed interfacial layering of [Bmim][NTf2] deposited on ns-SiOx suggests that the behavior of the IL-electrode interface in photoelectrochemical devices employing nanostructured nanoporous materials can be far more complex than expected under the hypothesis of an IL-based electrolyte in the stable liquid phase. The observed effects reported in this work could in principle also occur inside the bulk nanoporous matrix, where they could be further amplified by the extreme spatial confinement.

Using pressure to probe thermodynamic anomalies in tetrahedrally-bonded materials

Tetrahedrally-bonded materials, such as silicon, diamond, or gallium nitride, are characterized by a low coordination number of 4 in the crystalline phase and, in general, can exhibit a liquid phase with higher density and coordination. This leads to interesting thermodynamic behavior, including the lowering of the melting temperature with increasing pressure and the possible existence of distinct low- and high-density liquid phases. Using molecular dynamics simulations, we explored the role of pressure and the degree of tetrahedrality on the structure and phase equilibria between the crystalline and liquid phases of tetrahedrally-bonded materials. In addition to the thermodynamic melting point, we determined the temperature of mechanical stability (spinodal temperature) as a function of pressure. The latter temperature is relevant to the laser pulse rapid melting of tetrahedrally-bonded materials. The results of our simulations indicate the possibility of the existence of a thermodynamically stable low-density liquid phase of silicon at high pressures. Our simulation also suggests that GaN is unlikely to exhibit anomalous thermodynamic behavior due to a high degree of tetragonality preventing the formation of high-density liquid, even at high pressures.