Solution Phases Liquid Research Articles

Kinetic Simulations of Diffusion-Controlled Phase Transformations in Cu-Based Alloys

In this chapter, we present computational kinetics of diffusion-controlled phase transformations in Cu-based alloys, which becomes possible only most recently due to the establishment of the first atomic mobility database (MOBCU) for copper alloys. This database consists of 29 elements including most common ones for industrial copper alloys. It contains descriptions for both the liquid and Fcc_A1 phases. The database was developed through a hybrid CALPHAD approach based on experiments, first-principles calculations, and empirical rules. We demonstrate that by coupling the created mobility database with the existing compatible thermodynamic database (TCCU), all kinds of diffusivities in both solid and liquid solution phases in Cu-based alloys can be readily calculated. Furthermore, we have applied the combination of MOBCU and TCCU to simulate diffusion-controlled phenomena, such as solidification, nucleation, growth, and coarsening of precipitates by using the kinetic modules (DICTRA and TC-PRISMA) in the Thermo-Calc software package. Many examples of simulations for different alloys are shown and compared with experimental observations. The remarkable agreements between calculation and experimental results suggest that the atomic mobilities for Cu-based alloys have been satisfactorily described. This newly developed mobility database is expected to be continuously improved and extended in future and will provide fundamental kinetic data for computer-aided design of copper base alloys.

Intermolecular Interactions of Pyridine in Liquid Phase and Aqueous Solution Studied by Soft X-ray Absorption Spectroscopy

Abstract Intermolecular interactions of pyridine in liquid and in aqueous solution are studied by using soft X-ray absorption spectroscopy (XAS) at the C, N, and O K-edges. XAS of liquid pyridine shows that the N 1s→π* peak is blue shifted and the C 1s→π* peak of the meta and para sites is red shifted, respectively, as compared with XAS of pyridine gas. These shifts in liquid are smaller than those in clusters, indicating that the intermolecular interaction of liquid pyridine is weaker than that of pyridine cluster, as supported by the combination of quantum chemical calculations of the core excitation and molecular dynamics simulations of the liquid structure. On the other hand, XAS spectra of aqueous pyridine solutions (C5H5N)x(H2O)1−x measured at different molar fractions show that in the pyridine rich region, x>0.7, the C and N 1s→π* peak energies are not so different from pure liquid pyridine (x=1.0). In this region, antiparallel displaced structures of pyridine molecules are dominant as in pure pyridine liquid. In the O K-edge XAS, the pre-edge peaks sensitive to the hydrogen bond (HB) network of water molecules show the red shift of −0.15 eV from that of bulk water, indicating that small water clusters with no large-scale HB network are formed in the gap space of structured pyridine molecules. In the water rich region, 0.7>x, the N 1s→π* peaks and the O 1s pre-edge peaks are blue shifted, and the C 1s→π* peaks of the meta and para sites are red-shifted by increasing molar fraction of water. The HB network of bulk water is dominant, but quantum chemical calculations indicate that small pyridine clusters with the HB interaction between the H atom in water and the N atom in pyridine are still existent even in very dilute pyridine solutions.

Superhydrophobic Surfaces Made from Naturally Derived Hydrophobic Materials

Functional coatings that can achieve stable superhydrophobicity have the potential to significantly enhance a plethora of industrial applications ranging from building environmental control, phase change heat transfer, thermoelectric power generation, and hydrodynamic drag reduction. In order to create superhydrophobic surfaces, scientists have utilized a variety of surface structuring methods in combination with organosilane based alkyl and perfluorinated synthetic chemical coatings. Unfortunately, organosilane based alkyl and perfluorinated chemicals tend to be toxic, flammable, corrosive, difficult to dispose of, and damaging to the environment. Here, we develop two new methods to achieve superhydrophobicity using liquid phase deposition of cinnamic acid or myristic acid, both organic compounds derived from natural sources. By varying the liquid phase solution concentration, we develop deposition methods on scalable copper oxide microstructured surfaces capable of achieving apparent advancing contact a...

Effect of adding Te to layered GaSe crystals to increase the van der Waals bonding force

The interplanar binding strength of layered GaSe1-xTex crystals was directly measured using a tensile testing machine. The GaSe1-xTex crystals were grown by a low temperature liquid phase solution method under a controlled Se vapor pressure. The stoichiometry-controlled GaSe1-xTex crystal has the ε-polytype structure of GaSe, where the Te atoms are substituted for some of the Se atoms in the GaSe crystal. The effect of adding Te on the bonding strength between the GaSe layers was determined from direct measurements of the van der Waals bonding energy. The bonding energy was increased from 0.023 × 106 N/m2 for GaSe to 0.16 × 106 N/m2 for GaSe1-xTex (x = 0.106).

溶ける : 溶液と溶解平衡( 日常経験する物理・化学的現象のやさしい解説)

溶ける : 溶液と溶解平衡( 日常経験する物理・化学的現象のやさしい解説)

Experimental investigation and thermodynamic assessment of the Mo–Ni–Zr ternary system

The isothermal section of the Mo–Ni–Zr system at 1100°C was investigated by characterization of eight equilibrium alloys. X-ray diffraction (XRD) and electron probe microanalysis (EPMA) were used to identify the stable phases and obtain their compositions. The Mo–Ni–Zr system was then optimized by means of CALPHAD (CALculation of PHAse Diagrams) technique with the consideration of experimental data obtained in the present work and reported in the literature. The liquid, fcc, bcc and hcp solution phases, were modeled with (sub-)regular solution model. The compound Zr65Mo18−xNi16.5+x (τ1, cF96-Ti2Ni) was described as Zr2(Mo, Ni) based on its crystal structure and solubility range. While τ2 (Zr65Mo27.3Ni7.7) phase was modeled as a stoichiometric compound due to its limited homogeneity range. A set of self-consistent thermodynamic parameters for the Mo–Ni–Zr system was finally obtained. Comprehensive comparisons between the calculated and experimental phase diagram data show that the experimental information is satisfactorily accounted for by the present thermodynamic description. The liquidus projection and reaction scheme of the Mo–Ni–Zr system were also generated by using the present thermodynamic parameters.

Synthesis Methods of Two-Dimensional MoS2: A Brief Review

Molybdenum disulfide (MoS2) is one of the most important two-dimensional materials after graphene. Monolayer MoS2 has a direct bandgap (1.9 eV) and is potentially suitable for post-silicon electronics. Among all atomically thin semiconductors, MoS2’s synthesis techniques are more developed. Here, we review the recent developments in the synthesis of hexagonal MoS2, where they are categorized into top-down and bottom-up approaches. Micromechanical exfoliation is convenient for beginners and basic research. Liquid phase exfoliation and solutions for chemical processes are cheap and suitable for large-scale production; yielding materials mostly in powders with different shapes, sizes and layer numbers. MoS2 films on a substrate targeting high-end nanoelectronic applications can be produced by chemical vapor deposition, compatible with the semiconductor industry. Usually, metal catalysts are unnecessary. Unlike graphene, the transfer of atomic layers is omitted. We especially emphasize the recent advances in metalorganic chemical vapor deposition and atomic layer deposition, where gaseous precursors are used. These processes grow MoS2 with the smallest building-blocks, naturally promising higher quality and controllability. Most likely, this will be an important direction in the field. Nevertheless, today none of those methods reproducibly produces MoS2 with competitive quality. There is a long way to go for MoS2 in real-life electronic device applications.

Two-dimensional-growth small molecular hole-transporting layer by ultrasonic spray coating for organic light-emitting devices

Two-dimensional-growth small molecular organic thin film with high quality is fabricated by ultrasonic spray coating technology (USC) from the toluene solution of 4,4′,4″-tris (carbazol-9-yl) triphenylamine (TCTA). In comparison to the vacuum thermal evaporation (VTE) TCTA film, the USC-TCTA film obtained from liquid-phase solution possesses more uniform surface topography. The differences between the USC-TCTA and the VTE-TCTA in optical property, electrical property and formation mechanism are also studied in detail. Besides, to evaluate the hole transport and electron blocking ability of USC-TCTA film, the organic light-emitting devices (OLEDs) employing USC-TCTA film as hole transport layer are fabricated successfully. Additionally, the green OLEDs based on USC-TCTA film perform as well as the ones with VTE-TCTA film in current density, luminance, efficiency and color stability, and show even better tolerance to high bias voltage.

Thermodynamic assessment of the phase equilibria and prediction of glass-forming ability of the Al–Cu–Zr system

The thermodynamic description of the Al–Cu–Zr system was performed using the CALPHAD method. The solution phases liquid, fcc, bcc and hcp were described using a substitutional solution model. The compounds in the Al–Zr and Cu–Zr systems and the ternary compounds τ3, τ5, τ7 and τ8 were treated as a line compound in the Al–Cu–Zr system. The ternary compounds τ1, τ2, τ4, τ6, τ9 and τ11 were described as a stoichiometric compound. The enthalpies of mixing of the liquid phase at different temperatures and compositions, two invariant reactions, and five isothermal sections at 773, 873, 1073, 1273 and 1373K were taken into account in the present optimization work. A set of self-consistent and reliable thermodynamic parameters of the Al–Cu–Zr system was obtained. By searching the local minimum of the driving force for crystalline phases under the supercooled liquids, the thermodynamic parameters obtained in this assessment were later used for predicting composition dependencies of high glass-forming ability in the Al–Cu–Zr system. The predicted alloy compositions of high glass-forming ability are in satisfactory agreement with the available experimental data.

Polarizable Multipole-Based Force Field for Aromatic Molecules and Nucleobases.

Aromatic molecules with π electrons are commonly involved in chemical and biological recognitions. For example, nucleobases play central roles in DNA/RNA structure and their interactions with proteins. The delocalization of the π electrons is responsible for the high polarizability of aromatic molecules. In this work, the AMOEBA force field has been developed and applied to 5 regular nucleobases and 12 aromatic molecules. The permanent electrostatic energy is expressed as atomic multipole interactions between atom pairs, and many-body polarization is accounted for by mutually induced atomic dipoles. We have systematically investigated aromatic ring stacking and aromatic-water interactions for nucleobases and aromatic molecules, as well as base–base hydrogen-bonding pair interactions, all at various distances and orientations. van der Waals parameters were determined by comparison to the quantum mechanical interaction energy of these dimers and fine-tuned using condensed phase simulation. By comparing to quantum mechanical calculations, we show that the resulting classical potential is able to accurately describe molecular polarizability, molecular vibrational frequency, and dimer interaction energy of these aromatic systems. Condensed phase properties, including hydration free energy, liquid density, and heat of vaporization, are also in good overall agreement with experimental values. The structures of benzene liquid phase and benzene-water solution were also investigated by simulation and compared with experimental and PDB structure derived statistical results.

Thermodynamic reevaluation and experimental validation of the CsNO3-KNO3-NaNO3 system and its subsystems

Phase equilibria and thermodynamic properties of the CsNO3-KNO3-NaNO3 system and its three subsys-tems were optimized thermodynamically and validated experimentally. The liquid and end solid solution phases of the KNO3-NaNO3 and CsNO3-KNO3 systems were modeled using the substitutional solution and compound energy formalism models, respectively. The CsNO3-KNO3-NaNO3 ternary system was described thermodynamically based on the self-consistent thermodynamic parameters of the three binary systems. A set of thermodynamic parameters was obtained to reproduce the available information on the thermodynamic properties and phase equilibria. Melting temperature, enthalpy, and specific heat capacity of a eutectic sample were determined using differential scanning calorimetry(DSC). The results show a good consistency with the calculated results, suggesting the reliability of the current thermodynamic database. This work is useful for the construction of multicomponent nitrates and to provide guidance for the development of new medium for thermal energy storage.

Phase equilibria in the calcia-gadolinia-silica system

The phase equilibria in the CaO-Gd2O3-SiO2 system were investigated by heat treating precursor-derived powders at 1400 °C and 1600 °C, determining the resulting phase assemblages, and measuring the compositions of the liquid and solid solution phases. The stable ternary phases at 1400 °C include silico-carnotite (Ca3Gd2Si3O12), Ca/Gd-cyclosilicate (Ca3Gd2Si6O26), and the apatite solid solution field extending from Gd9.33(SiO4)6O2 to Ca2.75Gd7.25(SiO4)6O1.625. Of these, only apatite remains stable to 1600 °C. The high-temperature α- and α′-Ca2SiO4 polymorphs exhibit moderate Gd2O3 solubility. The results are compared to the equilibria for the related CaO-Y2O3-SiO2 system. The implications for understanding the interaction between rare earth containing thermal barrier coatings (TBCs) and silicate deposits (CMAS) are discussed.

Anti-Adhesive Behaviors between Solid Hydrate and Liquid Aqueous Phase Induced by Hydrophobic Silica Nanoparticles.

This study introduces an "anti-adhesive force" at the interface of solid hydrate and liquid solution phases. The force was induced by the presence of hydrophobic silica nanoparticles or one of the common anti-agglomerants (AAs), sorbitan monolaurate (Span 20), at the interface. The anti-adhesive force, which is defined as the maximum pushing force that does not induce the formation of a capillary bridge between the cyclopentane (CP) hydrate particle and the aqueous solution, was measured using a microbalance. Both hydrophobic silica nanoparticles and Span 20 can inhibit adhesion between the CP hydrate probe and the aqueous phase because silica nanoparticles have an aggregative property at the interface, and Span 20 enables the hydrate surface to be wetted with oil. Adding water-soluble sodium dodecyl sulfate (SDS) to the nanoparticle system cannot affect the aggregative property or the distribution of silica nanoparticles at the interface and, thus, cannot change the anti-adhesive effect. However, the combined system of Span 20 and SDS dramatically reduces the interfacial tension: emulsion drops were formed at the interface without any energy input and were adsorbed on the CP hydrate surface, which can cause the growth of hydrate particles. Silica nanoparticles have a good anti-adhesive performance with a relatively smaller dosage and are less influenced by the presence of molecular surfactants; consequently, these nanoparticles may have a good potential for hydrate inhibition as AAs.

Thermodynamic evaluation of the BaO-ZrO2-YO1.5 system

Based upon the experimental data available in the literature and present measurements, thermodynamic reassessments were initially performed on the binary BaO-ZrO2, BaO-YO1.5 systems, and the resultant thermodynamic parameters were then merged in combination with that of the previous ZrO2-YO1.5 system to derive a self-consistent thermodynamic description for the ZrO2-BaO-YO1.5 ternary system with limited ternary thermodynamic parameters. The Gibbs energies of all the liquid and terminal solid solution phases were treated by the substitutional solution model, the BZ phase featured by second solid solution described by the compound energy formalism (CEF) model, and the stoichiometric compound BZY424 and Ba2YZrO6-d modeled following the Neumann-Kopp rule. The calculated results agree well with the isothermal sections at 1600°C and 1750°C (1873K and 1923K) from both of the previous and present measured phase diagrams. This demonstrates that the thermodynamic parameters derived in the present work could be applicable to compositional optimizations of novel refractories for melting titanium alloys on the basis of this ternary oxide system.

Revisiting the formation of cyclic clusters in liquid ethanol.

The liquid phase of ethanol in pure and in non-polar solvents was studied at room temperature using Fourier transform infrared (FT-IR) and (1)H nuclear magnetic resonance (NMR) spectroscopies together with theoretical approach. The FT-IR spectra for pure ethanol and solution in cyclohexane at different dilution stages are consistent with (1)H NMR results. The results from both methods were best explained by the results of the density functional theory based on a multimeric model. It is suggested that cyclic trimers and tetramers are dominated in the solution of cyclohexane/hexane with the concentration greater than 0.5M at room temperature. In liquid ethanol, while the primary components at room temperature are cyclic trimers and tetramers, there is a certain amount (∼14%) of open hydroxide group representing the existence of chain like structures in the equilibria. The cyclic cluster model in the liquid and concentrated solution phase (>0.5M) can be used to explain the anomalously lower freezing point of ethanol (159 K) than that of water (273 K) at ambient conditions. In addition, (1)H NMR at various dilution stages reveals the dynamics for the formation of cyclic clusters.

Extraction and recovery of penicillin G from solution by cascade process of hollow fiber renewal liquid membrane

The feasibility of cascade process for penicillin G recovery utilizing hollow fiber renewal liquid membrane (HFRLM) technique was investigated and the optimal conditions were determined. Cascade process of HFRLM was carried out to recover penicillin G from the aqueous solution using di-n-octylamine in iso-octanol and kerosene as the liquid membrane phase and K2CO3 aqueous solution as the stripping phase. The mass transfer performance of the process was evaluated in a hollow fiber module with 1000 microporous and hydrophobic polypropylene (PP) hollow fibers. The cascade process of HFRLM was feasible for penicillin G recovery and the enrichment factor, extraction and recovery efficiency were larger than that of single-stage process. The stripping phase of 0.5molL−1K2CO3 solution could not only keep the efficiency of re-extraction, but also ensure the stability of penicillin G. Besides, the results indicated that 0.2molL−1 potassium dihydrogen phosphate solution as the buffer solution in the feed solution could greatly reduce the loss of penicillin G due to the pH fluctuation. In the cascade mode operated at the flow rates of 45mLmin−1 in the shell side and 20 mLmin−1 in the tube side, the extraction and recovery efficiency of 97% and 82% for penicillin G were achieved after 7 stages respectively. The cascade process of HFRLM for penicillin G recovery exhibits good potential in industrial application.

Quantum cluster equilibrium model of N-methylformamide-water binary mixtures.

The established quantum cluster equilibrium (QCE) approach is refined and applied to N-methylformamide (NMF) and its aqueous solution. The QCE method is split into two iterative cycles: one which converges to the liquid phase solution of the QCE equations and another which yields the gas phase. By comparing Gibbs energies, the thermodynamically stable phase at a given temperature and pressure is then chosen. The new methodology avoids metastable solutions and allows a different treatment of the mean-field interactions within the gas and liquid phases. These changes are of crucial importance for the treatment of binary mixtures. For the first time in a QCE study, the cis-trans-isomerism of a species (NMF) is explicitly considered. Cluster geometries and frequencies are calculated using density functional theory (DFT) and complementary coupled cluster single point energies are used to benchmark the DFT results. Independent of the selected quantum-chemical method, a large set of clusters is required for an accurate thermodynamic description of the binary mixture. The liquid phase of neat NMF is found to be dominated by the cyclic trans-NMF pentamer, which can be interpreted as a linear trimer that is stabilized by explicit solvation of two further NMF molecules. This cluster reflects the known hydrogen bond network preferences of neat NMF.

A thermodynamic model for non-stoichiometric cementite; the Fe–C phase diagram

On the basis of recently published experimental data a new thermodynamic model for the cementite phase was developed, accounting for its non-stoichiometry in equilibrium with α, γ and liquid solution phases. The predictions from the model were discussed in the context of experimental and ab initio data from the literature. Further, the model was compared to existing models for stoichiometric and non-stoichiometric cementite. It was shown that the resulting description is consistent with thermodynamic descriptions of the Fe–C system, excluding the non-stoichiometry of cementite, from the literature. Thus, the new model is suitable as a basis for multi-component systems correctly predicting the constitution of technically applied alloys.

Fabrication of Two-Dimensional Lateral Heterostructures of WS2 /WO3 ⋅H2 O Through Selective Oxidation of Monolayer WS2.

Two-dimensional (2D) lateral heterostructures have emerged as a hot topic in the fast evolving field of advanced functional materials , but their fabrication is challenging. The layer-structured WS2 was theoretically demonstrated to be inert to oxidation except for the monolayer, which can be selectively oxidized owing to the simultaneous interaction of oxygen with both sides. Combined with the theoretical calculations, a new method was developed for the successful construction of 2D lateral heterostructures of WS2 /WO3 ⋅H2 O in an ambient environment, based on a simple liquid-phase solution exfoliation. These lateral heterostructures of WS2 /WO3 ⋅H2 O have interesting properties, as indicated by enhanced photocatalytic activity toward the degradation of methyl orange (MO).

Solubilities of 10-undecenoic acid and geraniol in supercritical carbon dioxide

The solubilities of 10-undecenoic acid and geraniol in supercritical carbon dioxide were measured at 308, 313, 323 and 333K, and at pressures of 10–18MPa. Solubilities (in mole fraction) ranged from 0.4×10−3 to 17.4×10−3 for 10-undecenoic acid and 2.7×10−3 to 25×10−3 for geraniol, respectively. The AARD was around 11% and 5% for these models for 10-undecenoic acid and geraniol, respectively. The solubilities of both compounds showed retrograde behavior wherein the solubilities decrease with temperature at isobaric conditions. The solubility of geraniol was higher than 10-undecenoic acid at all investigated temperatures and pressures. The data were found to be self consistent based on the Mendez-Santiago model. New models based on association theory using van Laar and Margules activity coefficient models for solute in liquid phase were derived, and used to correlate the solubilities.