Eutectic Phase Diagram Research Articles

Phase behaviour of oleanolic acid, pure and mixed with stearic acid: Interactions and crystallinity

The phase behaviour of pure oleanolic acid (OLA) and in mixtures with stearic acid (SA) was characterized by differential scanning calorimetry (DSC), X-ray powder diffraction (XRD), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and nuclear magnetic resonance (NMR). The crystalline OLA as received (OLA ar) becomes amorphous after being dissolved in chloroform and vacuum-dried at 50 °C (OLA 50). Upon heating, both forms transform to the needle shape crystalline form (OLA 220). Dimerization through H-bonding between COOH groups was detected both in OLA ar and OLA 220. Dimers are stronger in OLA 220, where H-bonding also involves the alcohol groups and plays a role in the crystalline organization. A eutectic type phase diagram was established for mixtures, with the eutectic composition close to pure SA. Mixtures rich in SA are miscible in the liquid and in the amorphous solid states, where the presence of SA–OLA co-dimers, formed through H-bonding between carboxyl groups, was detected. Miscibility and SA crystallinity decrease drastically with the OLA content.

Phase equilibria in the systems AgInSe2-HgIn2Se4 and AgInSe2-HgSe

The equilibrium phase diagrams along the AgInSe2-HgIn2Se4 and AgInSe2-HgSe joins of the ternary system Ag2Se-HgSe-In2Se3 have been constructed using X-ray diffraction and differential thermal analysis. Both joins are pseudobinary, with eutectic phase diagrams (type V in Roseboom’s classification). The eutectics are located at ≃30 mol % HgIn2Se4 (melting point of 1000 K) and ≃54 mol % HgSe (993 K), respectively. Both systems have considerable terminal solid-solution ranges.

Thermophysical Properties of Binary Aliphatic Quaternary Ammonium Ionic Liquids: TMPAFSAxTFSA1-x

The anionic binary Ionic liquids; TMPAFSAxTFSA1-x were prepared as mixture of TMPATFSA and TMPAFSA. From the results of DSC analysis, the binary system showed the simple binary eutectic phase diagram and the eutectic point was found at the composition point of x = 0.33. In this system, each anion vibrated independently and showed isomerization equilibria displacement with temperature change. It was suggested that the equilibria displacements affected to the liquid structure and cis-trans isomerization of each anion played an important role in the solidification of TMPAFSAxTFSA1-x.

An investigation on eutectic binary phase diagram of volatilizable energetic materials by high pressure DSC

The eutectic binary phase diagrams of volatilizable energetic material 1,3,3-trinitroazetidine (TNAZ) with 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) and 1-methyl-2,4-dinitroimidazole (MDNI) have been investigated by high pressure differential scanning calorimeter (PDSC), respectively. The liquefying and melting processes of TNAZ/RDX and TNAZ/MDNI volatilizable systems have been studied. On the basis of the data of apparent fusion heat and liquefying temperature, the phase diagrams of apparent fusion heat (H) with composition (X) and liquefying temperature (T) with composition (X) were constructed, respectively. The results showed that the gasification or volatilization of easy volatile energetic materials could be efficiently restrained by high pressure atmosphere, and the perfect and ideal phase diagrams can be constructed. The eutectic temperatures for TNAZ/RDX and TNAZ/MDNI are measured to be 95.5 and 82.3 °C, respectively. The eutectic compositions of mole ratios for the two systems are obtained to be 93.55/6.45 (T–X method), 93.79/6.21 (H–X method) and 62.25/37.75 (T–X method), 63.29/33.71 (H–X method), respectively.

Metal surface nucleated supercritical fluid–solid–solid growth of Si and Ge/SiOx core–shell nanowires

High yields of both single-crystalline Si and Ge/SiOx core–shell nanowires were nucleated and grown in metal reactor cells under high-pressure supercritical fluid conditions, without the addition of catalyst particle seeds or a porous template. Nanowire growth was only achieved when the fluid medium of supercritical CO2 and the organometallic precursors were used in conjunction with a coordinating solvent, trioctylphosphine. The diameter and length of the nanowires are found to be in the ranges of 30 to 60 nm and 1 to 10 µm, respectively. The correlation of nanowire growth with the eutectic binary phase diagrams of the semiconductor–metal and the presence of metal impurities at the base of the synthesized nanowires suggest a supercritical fluid–solid–solid growth mechanism occurring from the reaction cell walls. The nanowires are characterized by transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy. The electrical characteristics for individually picked nanowires are also investigated by means of mechanical nanoprobing.

Phase relations in the LaB6-W2B5 system

The LaB6-W2B5 join in the ternary system La-B-W is shown to have a eutectic phase diagram with t e= 2220°C and a eutectic composition of 30 mol % LaB6 + 70 mol % W2B5. Data are presented on LaB6-containing systems potentially attractive for designing mixed-phase ceramics.

Growth of One-Dimensional Hierarchical Multilayered Indium Nanostructures

Novel one-dimensional (1D) hierarchical multilayered indium nanostructures were successfully synthesized via chemical reduction of InCl3·4H2O with Zn powder or foils in small alcohols, including methanol, ethanol, n-propyl alcohol, and the mixture of these alcohols. Electron diffraction (ED) and high-resolution transmission electronic microscopy (HRTEM) analyses revealed that the interesting multilayered nanostructures were grown from the assembly of elliptic indium monolayers along the [110] direction and the monolayer-density of the multilayered nanostructures was controllable by changing the alkyl-chain length of small alcohols. The TEM investigations for indium nanostructures obtained at different reaction stages revealed that the 1D hierarchical multilayered nanostructures gradually evolve from solid indium nanorods. On the basis of the TEM investigations and binary eutectic phase diagram of In−Zn, we proposed that the interesting evolvement of nanorods into 1D multilayered nanostructures resulted fr...

Revised Phase Diagram of the System NaF–NaBF4

Summary. The phase diagram of the binary system NaF– NaBF4 was determined using the thermal analysis method. Subsequent coupled analysis of the thermodynamic and phase diagram data was carried out to calculate the thermodynamically consistent phase diagram. The system NaF–NaBF4 forms a simple eutectic phase diagram with the calculated coordinates of the eutectic point: 8.1 mol% NaF, 91.9 mol% NaBF4, and 385.7 � C. The probable inaccuracy in the calculated binary phase diagram is 9 � C.

Binary solid–liquid phase diagram of the two diastereomer racemates of triglycidyl isocyanurate (TGIC)

Triglycidyl isocyanurate [2451-62-9] as a trifunctional epoxy monomer is mostly used as curing agent. It exists in the form of two diastereomer racemates according to the configuration of the three chiral carbon atoms in the molecule, i.e. beta- or RRR/ SSS and alpha- or RRS/ SSR. The binary solid–liquid phase diagram of the two diastereomer racemates has been determined by differential scanning calorimetry (DSC). The two diastereomer racemates have different crystalline structures and are physical mixtures with an eutectic phase diagram. The eutectic mixture melts at 92.3 ± 1.0 °C and has alpha-TGIC content of 93.44% by mass or mole. With the help of the phase diagram the ratio of the two diastereomer racemates in TGIC may be determined. The binary phase diagram shows that beta-TGIC can be separated with efficiency from the mixture and may serve for enantiomer synthesis of high optical activity giving rise to the development of novel polymers.

溶融鉛中の銅とイオウの相互溶解度

Equilibrium experiments were performed between molten lead and PbS-Cu2S mixed sulfide. The PbS-Cu2S system has an eutectic type phase diagram. Experimental temperatures were higher than the eutectic temperature in the range of 823 K to 1073 K. The compositions of PbS-Cu2S corresponded to the two phases of liquid mixed sulfide and solid PbS or liquid mixed sulfide and solid Cu2S at the experimental temperature. After cooling, a lead sample was analyzed for copper and sulfur. A good linear relationship between logarithms of copper concentration and reciprocal values of the absolute temperatures was obtained. In the case of sulfur, the similar tendency was obtained. The experimental values were compared with evaluated values calculated using the solubility of sulfur in the Pb-S binary system and the interaction parameter between copper and sulfur in liquid lead from the literature. The standard Gibbs energy of the following reaction, 2Cu(% in Pb) + S(% in Pb) = Cu2S(s), was evaluated by using the experiment results.

Solid state properties and effective resolution procedure for guaifenesin, 3-(2-methoxyphenoxy)-1,2-propanediol

Racemic expectorant guaifenesin, 3-(2-methoxyphenoxy)-1,2-propanediol 2 undergoes spontaneous resolution upon crystallization. This fact is confirmed by thermal analysis (single eutectic V-shape binary melting phase diagram, adequate entropy and free energy characteristics). Racemic 2 could be effectively resolved into ( S)- and ( R)- 2 by a preferential crystallization procedure. Single enantiomer drugs levomoprolol and levotensin were obtained by starting from enantiomeric 2 through the sulfite route.

Phase behaviour of stearic acid–stearonitrile mixtures: A thermodynamic study in bulk and at the air–water interface

The solid–liquid phase behaviour of stearic acid (SA) and stearonitrile (SN) in binary mixtures was investigated by differential scanning calorimetry (DSC), and the formation of SA–SN mixed monolayers at the air–water interface was followed by surface pressure–area ( π–A) measurements and by Brewster angle microscope (BAM) observation. The solid–liquid phase diagram is a eutectic type phase diagram, with the eutectic composition 0.90 < X SN < 0.95 and T eut = 40.9 °C. The DSC results also suggest that the two components are immiscible in the solid phase but form a liquid mixture with positive deviations to the ideal behaviour. At the air–water interface, the two components form liquid condensed monolayers in the entire range of compositions, at low surface pressures, while solid mixed monolayers only form at high surface pressures for X SN < 0.8. Thermodynamic analysis indicates that SA and SN are miscible in the liquid condensed phase, with negative deviations from the ideal behaviour. The variation of the collapse surface pressure of mixed monolayers also indicates miscibility at the air–water interface.

Phase Diagrams of Binary Crystalline−Crystalline Polymer Blends

A thermodynamically self-consistent theory has been developed to establish binary phase diagrams for two-crystalline polymer blends by taking into consideration all interactions including amorphous-amorphous, crystal-amorphous, amorphous-crystal, and crystal-crystal interactions. The present theory basically involves combination of the Flory-Huggins free energy for amorphous-amorphous isotropic mixing and the Landau free energy of polymer solidification (e.g., crystallization) of the crystalline constituents. The self-consistent solution via minimization of the free energy of the mixture affords determination of eutectic, peritectic, and azeotrope phase diagrams involving various coexistence regions such as liquid-liquid, liquid-solid, and solid-solid coexistence regions bound by liquidus and solidus lines. To validate the present theory, the predicted eutectic phase diagrams have been compared with the reported experimental binary phase diagrams of blends such as polyethylene fractions as well as polycaprolactone/trioxane mixtures.

PHASE-FIELD SIMULATIONS OF EUTECTIC SOLIDIFICATION USING AN ADAPTIVE FINITE ELEMENT METHOD

A finite element method with a semi-implicit time update and an adaptive mesh refinement is used to numerically simulate characteristic growth morphologies in binary eutectic alloys for varying process conditions. The evolution equations are based on a recently developed phase-field model.1 Microstructure formations in typical temperature-composition regions of the eutectic phase diagram are computed showing single cellular primary phase growth, melting of eutectics, eutectic and off-eutectic solidification. We consider 2D and 3D lamellar two-phase growths, analyze the angle conditions at the eutectic triple junctions for different surface entropy data and discuss the occurrence of wetting along the solid-solid interface.

Interaction of (+)-Catechin with a Lipid Bilayer Studied by the Spin Probe Method

The interaction of (+)-catechin with a lipid bilayer was examined by the spin probe method. The spin probe, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), was dissolved in an aqueous dipalmitoylphosphatidylcholine (DPPC) dispersion containing (+)-catechin. The temperature dependence of the TEMPO parameter was measured. The increase of this parameter due to pretransition was eliminated by the addition of (+)-catechin, suggesting that it was adsorbed to the lipid membrane surface in the gel state, which hindered the change of the membrane from a flat to wavy structure. In the temperature region of the main transition, the TEMPO parameter increased rapidly, then gradually with increasing temperature, which could be explained by the eutectic phase diagram. The rotational correlation time of a spin probe 16-doxylstearic acid and the order parameter of 5-doxylstearic acid in the aqueous dispersion system of egg yolk phosphatidylcholine revealed that the motion of the alkyl chain in the liquid crystal state was hindered in the center of the membrane as well as near the surface by the adsorption of (+)-catechin.

Solid state properties of 1,2-epoxy-3-(2-methoxyphenyloxy)-propane—valuable intermediate in non-racemic drug synthesis

Racemic 1,2-epoxy-3-(2-methoxyphenyloxy)-propane 1 undergoes spontaneous resolution upon crystallization. This fact is confirmed by coincidence of the IR spectra of racemic and scalemic crystalline samples of 1, by thermal analysis (single eutectic V-shape binary melting phase diagram), and X-ray analysis (space group P2 12 12 1, Z = 4). Racemic 1 could be resolved into ( S)-(+)- and ( R)-(−)- 1 by a preferential crystallization procedure.

Polythermic Section B4C-LaB6 in the Ternary System La-B-C

The interaction was studied and the polythermic section B4C-LaB6 was constructed for the ternary system La-B-C described by a eutectic phase diagram.

Physicochemical analysis and structure of melts of the system LiF–NaF–K 2NbF 7

The complex physicochemical analysis of the system LiF–NaF–K 2NbF 7, based on the phase diagram, density, surface tension, and viscosity measurements, as well as on the X-ray diffraction and IR spectroscopic analyses, was performed. The results proved that the investigated system forms a simple eutectic phase diagram with the coordinates of the ternary eutectic point 16 mol% LiF, 31 mol% NaF, 53 mol% K 2NbF 7, and t e =585 °C. The probable inaccuracy of temperature of primary crystallization in the calculated ternary phase diagram is 4.3 °C. From the molar volume, surface tension, and viscosity excesses, as well as from the X-ray diffraction and IR spectroscopic measurements of the quenched melts, it follows that the formation of the [NbF 8] 3− anions in the liquid phase was confirmed by all of the studied physicochemical parameters and is the general feature of this system.

Generalised ‘Jackson–Hunt’ model for eutectic solidification at low and large Peclet numbers and any binary eutectic phase diagram

Abstract Based on the generalised ‘Jackson–Hunt’ model from Donaghey and Tiller for eutectic solidification of binary alloys, a relation between growth velocity, lamellar spacing and interface undercooling for any binary eutectic phase diagrams and any Peclet number is derived. This relation is then used to propose a generalised scaling law for eutectic growth. The predictions of this generalised scaling law are discussed for extremely different eutectic phase diagrams and compared with predictions made by the TMK-model for symmetrical phase diagrams.

Crystallization of D-mannitol in binary mixtures with NaCl: phase diagram and polymorphism.

To study the crystallization, polymorphism, and phase behavior of D-mannitol in binary mixtures with NaCl to better understand their interactions in frozen aqueous solutions. Differential scanning calorimetry, hot-stage microscopy, Raman microscopy, and variable-temperature X-ray diffractometry were used to characterize D-mannitol-NaCl mixtures. NaCl and D-mannitol exhibited significant melt miscibility (up to 7.5% w/w or 0.20 mole fraction of NaCl) and a eutectic phase diagram (eutectic composition 7.5% w/w NaCl; eutectic temperature 150 degrees C for the alpha and beta polymorphs of D-mannitol and 139 degrees C for the delta). The presence of NaCl did not prevent mannitol from crystallizing but, depending on sample size, affected the polymorph crystallized: below 10 mg, delta was obtained; above 100 mg, alpha was obtained. Pure mannitol crystallized under the same conditions first as the delta polymorph and then as the a polymorph, with the latter nucleating on the former. KCl showed similar eutectic points and melt miscibility with D-mannitol as NaCl. LiCl yielded lower eutectic melting points, inhibited the crystallization of D-mannitol during cooling, and enabled the observation of its glass transition. Despite their structural dissimilarity, significant melt miscibility exists between D-mannitol and NaCl. Their phase diagram has been determined and features polymorph-dependent eutectic points. NaCl influences the polymorphic behavior of mannitol, and the effect is linked to the crystallization of mannitol in two polymorphic stages.