Solution Phase Properties Research Articles

Understanding the Multiple Roles of Solvation Structure in the Performance of Next-Generation Sodium Metal Battery Systems

Sodium metal batteries have become one of the most attractive targets for beyond-lithium electrochemical energy storage opportunities in recent years due to their low cost, high abundance, and sustainability when compared to popular lithium systems. The adoption of sodium metal batteries has been limited, however, by their instability and poor cycle life. Current efforts to resolve instability of the sodium metal anode have primarily focused on the adaptation of electrolyte systems (including solvents, salts, and additives) from the more researched lithium metal battery systems with some success.1 However, it has become clear that sodium metal batteries behave distinctly for their alkali counterpart, and will require new electrolyte design strategies. In order to inform solvation shell dynamics and SEI formation, this work explores 2 common salts (NaPF6 and NaTFSI) and 2 common solvents (diglyme and FEC) employed in sodium metal battery electrolytes. The selected components possess a range of desirable molecular structures bulk properties, allowing us to diagram the connections between their solvation structures and bulk solution phase properties. We achieve this by probing solvation shells with (1) Raman and (2) NMR spectroscopy, and following these chemical dynamics through to their impacts on electrolyte decomposition with in operando (3)electrochemical quartz crystal microbalance (EQCM) and SEI composition (4) XPS to morphology (5) SEM. Finally, we correlate these fundamental electrochemical and chemical observations to traditional cycling analysis as well as electrochemical impedance spectroscopy (EIS). We elucidate distinct roles of anion and solvent for ion transport and SEI formation in sodium systems, providing crucial understanding required for informed Na electrolyte design. 1. Sarkar, S.; Lefler, M.J.; Vishnugopi, B. Nuwayhid, R.B.; Love, C.T.; Carter. R.; Mukherjee, P.P.; Fluorinated ethylene carbonate as additive to glyme electrolytes for robust sodium solid electrolyte interface. Cell Reports Physical Science , 2023, 4, 101356.

1,1'-Biolympicenyl: A Stable Non-Kekulé Diradical with a Small Singlet and Triplet Energy Gap.

Dimerization of delocalized polycyclic hydrocarbon radicals is a simple and versatile method to create diradicals with tailored electronic structures and accessible high-spin states. However, the synthesis is challenging, and the stability issue of the diradicals remains a concern. In this study, we present the synthesis of a stable non-Kekulé 1,1'-biolympicenyl diradical 1 using a protection-oxidation-protection strategy. Diradical 1 demonstrated exceptional stability, with a solution half-life time exceeding 3.5 years and a solid state thermal decomposition temperature above 300 °C. X-ray crystallographic analysis revealed its intersected molecular structure and tightly bound dimer configuration. A singlet ground state with a small singlet-triplet energy gap is consistently identified using electron paramagnetic resonance (EPR) and a superconducting quantum interference device (SQUID) in a rigid matrix, and the triplet state is thermally accessible at room temperature. The solution phase properties were systematically examined through EPR, absorption spectroscopy, and cyclic voltammetry, revealing a rotational motion in the slow-motion regime and multistage redox characteristics. This study presents an efficient synthetic and stabilization strategy for organic diradicals, enabling the development of various high-spin functional materials.

Ion Mobility-Mass Spectrometry Strategies to Elucidate the Anhydrous Structure of Noncovalent Guest/Host Complexes.

Structural mass spectrometry (MS) techniques are fast and sensitive analytical methods to identify noncovalent guest/host complexation phenomena for desirable solution-phase properties. Current MS-based studies on guest/host complexes of drug and drug-like molecules are sparse, and there is limited guidance on how to interpret MS information in the context of host nanoencapsulation and inclusion. Here, we use structural MS strategies, combining energy-resolved MS (ERMS), ion mobility-MS (IM-MS), and computational modeling, to characterize 14 chemically distinct drug and drug-like compounds for their propensity to form guest/host complexes with the widely used excipient, beta-cyclodextrin (βCD). The majority (11/14) yielded a 1:1 guest/host complex, and ion mobility collision cross section (CCS) analysis provided subtle evidence of gas-phase compaction of complexes in both polarities. The three distinct dissociation channels observed in ERMS (i.e., charged βCD, charged guest, and partial guest loss) were used to direct charge-site assignments for computational modeling, and structural candidates were prioritized using helium-derived CCS measurements combined with root-mean-square distance analysis. The combined analytical information from ERMS, IM-MS, and computational modeling suggested that the majority of anhydrous complexes are inclusion complexes with βCD. Taken together, this work demonstrates a roadmap for how multiple MS-based analytical measurements can be combined to interpret the structures that guest/host complexes adopt in the absence of water.

Elastic Properties of B2-NiAl with W addition: A first-principles study

The effect of tungsten alloying on the elastic properties of B2-NiAl at low-temperature and high-temperature distribution of W atoms on sublattices. By means of the exact muffin-tin orbitals method in conjunction with the coherent potential approximation, the constants C11,C12,C44, Young's modulus E, shear modulus G, Cauchy pressure values, G/B ratios are calculated. Using phenomenological criteria of the correlation between ductility and elastic properties of solution phases, it has been shown that the addition of tungsten could yield improved ductility for B2-NiAl in both types of alloys. It is established that with the high-temperature distribution of W atoms on the Al sublattice, there is a loss of mechanical stability and a decrease in mechanical properties with increasing W concentration. In alloys with a low-temperature distribution of tungsten atoms between Al and Ni sites a unique combination of properties occurs: in addition to the ductility enhancement, a simultaneous increase of the elastic constants C44 and C11 and C11, shear modulus G, Young's modulus E with increasing W content is observed. The differences in the behavior of elastic constants in alloys with different types of tungsten distribution on NiAl sublattices are analyzed by calculating the density of electronic states. Keywords: NiAl, alloying elements, tungsten, elastic properties, ductility, first-principles calculations.

Упругие свойства B2-NiAl с добавлением W: исследование из первых принципов

The effect of tungsten alloying on the elastic properties of B2 NiAl at low-temperature and high-temperature distribution of W atoms on sublattices. By means of the exact muffin-tin orbitals method in conjunction with the coherent potential approximation, the constants C11, C12, C44, Young's modulus E, shear modulus G, Cauchy pressure values, G/B ratios are calculated. Using phenomenological criteria of the correlation between ductility and elastic properties of solution phases, it has been shown that the addition of tungsten could yield improved ductility for B2 NiAl in both types of alloys. It is established that with the high-temperature distribution of W atoms on the Al sublattice, there is a loss of mechanical stability and a decrease in mechanical properties with increasing W concentration. In alloys with a low–temperature distribution of tungsten atoms between Al and Ni sites a unique combination of properties occurs: in addition to the ductility enhancement, a simultaneous increase of the elastic constants C44 and C11, shear modulus G, Young modulus E with increasing W content is observed. The differences in the behavior of elastic constants in alloys with different types of tungsten distribution on NiAl sublattices are analyzed by calculating the density of electronic states.

Synthesis-on-substrate of quantum dot solids.

Perovskite light-emitting diodes (PeLEDs) with an external quantum efficiency exceeding 20% have been achieved in both green and red wavelengths1-5; however, the performance of blue-emitting PeLEDs lags behind6,7. Ultrasmall CsPbBr3 quantum dots are promising candidates with which to realize efficient and stable blue PeLEDs, although it has proven challenging to synthesize a monodispersed population of ultrasmall CsPbBr3 quantum dots, and difficult to retain their solution-phase properties when casting into solid films8. Here we report the direct synthesis-on-substrate of films of suitably coupled, monodispersed, ultrasmall perovskite QDs. We develop ligand structures that enable control over the quantum dots' size, monodispersity and coupling during film-based synthesis. A head group (the side with higher electrostatic potential) on the ligand provides steric hindrance that suppresses the formation of layered perovskites. The tail (the side with lower electrostatic potential) is modified using halide substitution to increase the surface binding affinity, constraining resulting grains to sizes within the quantum confinement regime. The approach achieves high monodispersity (full-width at half-maximum = 23 nm with emission centred at 478 nm) united with strong coupling. We report as a result blue PeLEDs with an external quantum efficiency of 18% at 480 nm and 10% at 465 nm, to our knowledge the highest reported among perovskite blue LEDs by a factor of 1.5 and 2, respectively6,7.

Probing solution structure of the pentameric ligand-gated ion channel GLIC by small-angle neutron scattering

Pentameric ligand-gated ion channels undergo subtle conformational cycling to control electrochemical signal transduction in many kingdoms of life. Several crystal structures have now been reported in this family, but the functional relevance of such models remains unclear. Here, we used small-angle neutron scattering (SANS) to probe ambient solution-phase properties of the pH-gated bacterial ion channel GLIC under resting and activating conditions. Data collection was optimized by inline paused-flow size-exclusion chromatography, and exchanging into deuterated detergent to hide the micelle contribution. Resting-state GLIC was the best-fit crystal structure to SANS curves, with no evidence for divergent mechanisms. Moreover, enhanced-sampling molecular-dynamics simulations enabled differential modeling in resting versus activating conditions, with the latter corresponding to an intermediate ensemble of both the extracellular and transmembrane domains. This work demonstrates state-dependent changes in a pentameric ion channel by SANS, an increasingly accessible method for macromolecular characterization with the coming generation of neutron sources.

Enhancing and Mitigating Radiolytic Damage to Soft Matter in Aqueous Phase Liquid-Cell Transmission Electron Microscopy in the Presence of Gold Nanoparticle Sensitizers or Isopropanol Scavengers.

In this work, we describe the radiolytic environment experienced by a polymer in water during liquid-cell transmission electron microscopy (LCTEM). We examined the radiolytic environment of aqueous solutions of poly(ethylene glycol) (PEG, 2400 g/mol) in the presence of sensitizing gold nanoparticles (GNPs, 100 nm) or radical scavenging isopropanol (IPA). To quantify polymer damage, we employed post-mortem analysis via matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS). This approach confirms IPA (1-10% w/v) can significantly mitigate radiolysis-induced damage to polymers in water, while GNPs significantly enhance damage. We couple LCTEM experiments with simulations to provide a generalizable strategy for assessing radiolysis mitigation or enhancement. This study highlights the caution required for LCTEM experiments on inorganic nanoparticles where solution phase properties of surrounding organic materials or the solvent itself are under investigation. Furthermore, we anticipate an increased use of scavengers for LCTEM studies of all kinds.

Second-nearest-neighbor modified embedded-atom method interatomic potential for V-M (M = Cu, Mo, Ti) binary systems

Interatomic potentials for V-M (M = Cu, Mo, Ti) binary systems have been developed within the framework of the second-nearest-neighbor modified embedded-atom method (2NN MEAM) formalism. The potentials reproduce a wide range of fundamental material properties such as thermodynamic and structural properties of compound and solution phases in reasonable agreement with experimental data or CALPHAD and first-principles calculations. The reasonable reproduction of material properties implies that the potentials can be combined with those of V-H and M-H systems for a permeability study of hydrogen in vanadium alloys or can be extended for further development of V-containing ternary system potentials.

Second-nearest-neighbor modified embedded-atom method interatomic potential for Cu-M (M = Co, Mo) binary systems

Second-nearest-neighbor modified embedded-atom method (2NN MEAM) interatomic potentials for Cu-M (M = Co, Mo) binary systems have been developed. The Cu-M potentials can be extended to Pt-Cu-M ternary 2NN MEAM potentials being combined with already existing Pt-M potentials and can be utilized for atomistic simulations to design inexpensive and efficient platinum alloy catalysts. The potentials reproduce fundamental material properties such as structural and thermodynamic properties of compound and solution phases in reasonable agreement with experimental data. Herein, the validity of the developed potentials for atomistic simulation is ascertained.

Thermodynamic assessment of the Te-X (X = As, Si, Co) systems

Thermodynamic assessment of the Te-X (X = As, Si, Co) binary systems has been carried out using the CALculation of Phase Diagrams (CALPHAD) method. The thermodynamic parameters were evaluated based on the available experimental data in the literature. Thermodynamic models were constructed for all the phases in the three systems. The substitutional solution model was employed to describe the thermodynamic properties of solution phases including liquid, (Te), (As), (Si), and (Co). Due to the existence of associate species Si2Te3 and the difficulty of describing the liquid phase by the substitutional solution model, the associate model was adopted to describe the liquid phase in the Te-Si system. The intermetallic compounds in the Te-As and Te-Si systems were treated as stoichiometric phases and the compounds βCoTe and γCoTe2 in the Te-Co system were modeled by using sublattice model due to the homogeneity range. A set of self-consistent thermodynamic parameters for the Te-X (X = As, Si, Co) systems was obtained. Comparisons between the calculated results and experimental data available in the literature show that almost all the reliable experimental information can be satisfactorily accounted for by the present modeling.

Aqueous phase properties on governing particle coagulation and mechanism nucleation in one-step emulsion polymerization of styrene

As is well known, changing continuous phase properties has a great influence on the nucleation mechanism and particle size, and the addition of electrolytes or alcohol is the main mean to control the properties of solution phase. In this study, a series of experiments about polystyrene emulsion polymerization were produced by adding K2CO3 and alcohols in different types and contents, so as to study the essential reasons for the influence of solution phase properties on the growth process of particles and the synergistic effect between electrolytes and alcohols. In the presence of methanol-water polymerization systems, the particle size of polystyrene latex particles was enlarged obviously with the increase of methanol content when 0.6 wt% K2CO3 was contained, but there are no significant changes for the particle size with 0.1 wt% K2CO3. For the alcohols with different chain lengths, the particle diameters as follows: Dpropanol (212.6 nm) > Dethanol (123.1 nm) > Dmethanol (90.75 nm). They indicate that adding alcohol to the solution could promote particle coagulation by reducing dielectric constant of the continuous phase. As a result, the polystyrene latex particles with large-scale particle size can be acquired using controlling particle coagulation by changing aqueous phase composition.

Modified embedded-atom method interatomic potential for the Mg–Zn–Ca ternary system

Mg–Zn–Ca alloys are representative Mg alloys with high formability at room temperature. Their high formability is thought to be related to slip, twinning, and recrystallization of the alloys, but the detailed mechanisms have not yet been clarified. To enable atomistic simulations for investigating those behaviors, an interatomic potential for the Mg–Zn–Ca ternary system was developed. The development was based on the second nearest-neighbor modified embedded-atom method formalism, combining previously developed Mg–Zn and Mg–Ca potentials with the newly developed Zn–Ca binary potential. The Zn–Ca and Mg–Zn–Ca potentials reproduce structural, elastic, and thermodynamic properties of compounds and solution phases of relevant alloy systems in reasonable agreement with experimental data, first-principles and CALPHAD calculations. The applicability of the developed potentials is demonstrated through calculations of the effects of Zn and Ca solutes on the generalized stacking fault energy for various slip systems, segregation energy on twin boundaries, and volumetric misfit strain.

Using DTA/DSC data for assessment of the Toop and Muggianu predictive models for the Ag–Au–In ternary

The relative performance of the Muggianu and Toop methods of preliminary prediction of thermodynamic properties of solution phases is tested using Ag–Au–In ternary as a model system, which was recently studied by the present authors. The temperatures of solids, monovariant reaction (where appropriate) and liquids, as well as the heat of melting of solid solutions, were measured by DTA/DSC for five ternary samples. Different extrapolation models generate very different descriptions of phase equilibria. However, accounting for ternary interactions brings all the results into moderately close agreement. In both methods, the values of ternary parameters for liquid phase are more negative than for solid phases (about twice in modulo in Muggianu one and up to ten times in Toop case). This implies the stabilization of liquid in central concentration region. Neither predictive model captures this without accounting for ternary interactions.

The potential of mechanical alloying to improve the strength and ductility of Mo–9Si–8B–1Zr alloys – experiments and simulation

Multi-phase Mo–Si–B alloys were intensively researched during the last decade as they are promising candidates for high temperature applications beyond the capabilities of single-crystalline Ni-based superalloys. Small additions of Zr improve the mechanical properties of the Mo solid solution phase (Moss), especially it lowers the brittle-to-ductile transition temperature and improves the fracture toughness. This work shows how mechanical alloying (MA) as the crucial step of powder metallurgical (PM) production will significantly influence the materials mechanical properties of Mo–9Si–8B–1Zr alloys in a wide temperature range from room temperature up to 1400 °C. The formation, continuity and length scale of the individual phases during PM processing is evaluated in detail using experimental methods and numerical studies. Furthermore, the mechanisms of deformation and fracture of the bulk materials are discussed with respect to the microstructural features. For comparison of the mechanical properties achieved by PM processing we produced the similar alloy composition by a conventional solidification process and characterized it by the same evaluation methods.

Forest monitoring: Substantiating cause-effect relationships

Monitoring of forest condition and tree performance is a long-term activity to provide data, substantiated cause-effects relationships and conclusions for environmental policies and forest management. Within this context the concept of tree and forest health, selection of response and predictor variables and challenges during statistical analyses are addressed.The terms tree and forest health are often used to characterise the performance of trees or the condition of forest ecosystems, however, the actual meanings may differ considerably. For the sake of a more coherent perception of the term health in scientific contexts and taking into account the meaning of disease(s) a more adjusted use of ‘health’ is recommended.Apart from the role of a working hypothesis, the selection process of meaningful response and predicting parameters is treated. On the response site the focus is on tree-related parameters like radial stem increment, crown condition, and foliar element concentrations. Each parameter reveals problems with specific implications for statistical model building. As drivers chemical properties of deposition, soil solution and soil solid phase, further foliar element concentrations, meteorological and air quality parameters are adduced. Additionally modelled plot-related values derived from external networks can be considered.Multiple regression as one of the core methods calls for unstructured residuals. To find optimal solutions especially in more intensive monitoring programmes with limited numbers of plots and many parameters is a challenge. Longitudinal and time series analyses may offer alternatives and widen the scope. While classical geostatistics may help to control spatial autocorrelation, possibilities to enlarge ecological and climatic gradients due to the inclusion of plots from similar programmes in suitable regions have to be considered as well.

Alcohol Clustering Mechanisms in Supercritical Carbon Dioxide Using Pulsed-Field Gradient, Diffusion NMR and Network Analysis: Feedback on Stepwise Self-Association Models.

Co-solvent clustering in complex fluids is fundamental to solution phase processes, influencing speciation, reactivity, and transport. Herein, methanol (MeOH) clustering in supercritical carbon dioxide is explored with pulsed-field gradient, diffusion-ordered nuclear magnetic resonance spectroscopy (DOSY-NMR), and molecular dynamics (MD) simulations. Refinements on the application of self-association models to DOSY-NMR experiments on clustering species are presented. Network analysis of MD simulations reveals an elevated stability of cyclic tetrameric clusters across MeOH concentrations, which is consistent with experimental DOSY-NMR molecular cluster distributions calculated with self-association models that include both cooperative cluster assembly and entropic penalties for the formation of large clusters. Simulations also detail the emergence of cluster-assembly and cluster-disassembly reactions that deviate from stepwise monomer addition or removal. This combination of experiment, simulation, and novel analyses facilitates refinement of models that describe co-solvent aggregation with far-reaching impact on the prediction of solution phase properties of complex fluids.

Second nearest-neighbor modified embedded-atom method interatomic potentials for the Pd-M (M = Al, Co, Cu, Fe, Mo, Ni, Ti) binary systems

Palladium (Pd) has attracted attention as one of the major components of noble metal catalysts due to its excellent reactivity to a wide range of catalytic reactions. It is important to predict and control the atomic arrangement in catalysts because their properties are known to be affected by it. Therefore, to enable atomistic simulations for investigating the atomic scale structural evolution, we have developed interatomic potentials for Pd-M (M = Al, Co, Cu, Fe, Mo, Ni, Ti) binary systems based on the second nearest-neighbor modified embedded-atom method formalism. These potentials reproduce various fundamental properties of the alloys (the structural, elastic and thermodynamic properties of compound and solution phases, and order-disorder transition temperature) in reasonable agreements with experimental data, first-principles calculations and CALPHAD assessments. Herein, we propose that these potentials can be applied to the design of robust bimetallic catalysts by predicting the shape and atomic arrangement of Pd bimetallic nanoparticles.

Solid solution softening and enhanced ductility in concentrated FCC silver solid solution alloys

The major adoptions of silver-based bonding wires and silver-sintering methods in the electronic packaging industry have incited the fundamental material properties research on the silver-based alloys. Recently, an abnormal phenomenon, namely, solid solution softening, was observed in stress vs. strain characterization of Ag-In solid solution. In this paper, the mechanical properties of additional concentrated silver solid solution phases with other solute elements, Al, Ga and Sn, have been experimentally determined, with their work hardening behaviors and the corresponding fractography further analyzed. Particularly, the concentrated Ag-Ga solid solution has been discovered to possess the best combination of mechanical properties, namely, lowest yield strength, highest ductility and highest strength, among the concentrated solid solutions of the current study. Microscopically, a clear evidence of narrow twin lamella feature has been observed in the Ag-Ga solid solution, and further identified as the deformation twinning, using high resolution transmission electron microscopy (HRTEM). To explain solid solution softening mechanism in low Peierls potential FCC metals, the authors have proposed a self-contained theoretical interpretation associated with fractional kink-pairs formation, and originally introduced the concept of the short range order (SRO) induced localized homologous temperature (LHT). Furthermore, the mechanism of twinning-induced plasticity (TWIP) can be referred as the underlying reason of the enhanced ductility in the Ag-Ga solid solution alloy. With such excellent mechanical properties, the Ag-Ga solid solution alloy is expected to have a great potential in the development of advanced joining materials for the various applications in electronics industries.

Modified embedded-atom method interatomic potentials for pure Zn and Mg-Zn binary system

Interatomic potentials for pure Zn and Mg–Zn binary system have been developed on the basis of the second nearest-neighbor modified embedded-atom method formalism. The potentials describe fundamental material properties of pure Zn (bulk, defect, and thermal properties) reasonably and reproduce the alloy behavior (thermodynamic, structural, and elastic properties of compounds and solution phases) of Mg-Zn alloys well in good agreement with experiments, first-principles and CALPHAD. The applicability of the developed potentials to atom-scale investigations on the slip behavior of Mg-Zn alloys is also demonstrated by showing that the calculated effects of Zn on the general stacking fault energy on the basal, prismatic and pyramidal planes are consistent with first-principles calculations.