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Abstract  

The phase diagram of R(+)-S(-) efaroxan hydrochloride (Tfus.(R)=245.10.3C. ΔHfus.(R)=119.63.0 J g-1) shows a racemic compound. The melting temperature and melting enthalpy of the compound are: Tfus.(RS)=247.80.2C and ΔHfus. (RS)=124.62.4 J g-1. A solid ↔ solid transformation takes place at Ttrs.=1801C, ΔHtrs.=15.00.4 J g-1. This transition is observed between 3 and 97% R(+). The stability of the racemic compound already established in a previous study was confirmed by the value of Petterson's coefficient (i=1.19). The two eutectic positions at 20 and 80% R(+) that define the range over which the racemic compound is found, exclude the use of resolution methods by preferential crystallization.

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Solid–liquid phase diagrams of binary mixtures

Acetylsalicylic acid(1) + E(2) (E = salicylic acid, polyethylene glycol 4000, d-mannitol)

Journal of Thermal Analysis and Calorimetry
Authors: Luigi Campanella, Valentina Micieli, Mauro Tomassetti, and Stefano Vecchio

Abstract  

This study reports the investigation of three binary mixtures represented by acetylsalicylic acid (ASA) with its most important degradation product, salicylic acid (SA), and two of the most commonly used excipients (polyethylene glycol 4000 (PEG-4000) and d-mannitol (MA)). The liquidus and solidus equilibrium temperatures determined by DSC for pure components and solid binary mixtures at a fixed composition (mass fraction of ASA, w) were used to construct the corresponding solid–liquid phase diagrams. On the basis of the DSC results, the binary mixtures ASA/SA and ASA/PEG exhibit eutectic behavior (T eu = 155.0 ± 0.5 °C, w eu = 0.55 ± 0.02 and T eu = 53.3 ± 0.5 °C, w eu = 0.32  ± 0.01 ), respectively), while the binary mixture ASA/MA revealed the presence of a monotectic with a mean melting temperature of 162.2 °C in the range 0.2 < w 1 < 0.8. The composition of the two eutectics formed was confirmed by the related Tamman triangles. Finally, the liquidus curves of ASA/SA and ASA/PEG mixtures were also successfully predicted providing suitable polynomial (second-order) fitting equations.

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Abstract  

The phase diagram of the binary AgNO3–CsNO3 system was constructed using differential thermal analysis (DTA) technique in the range 300–700 K. The apparatus is described briefly. The results exhibit a congruently melting compound CsNO3·AgNO3 (m.p.=453 K) characterized by two allotropic varieties and , an incongruently melting compound AgNO3·CsNO3 (m.p.=450 K) with three forms , and , two eutectics (16 mol% CsNO3, 442 K and 32.5 mol% CsNO3, 445 K) and a peritectic (38mol% CsNO3, 450 K). The occurrence of the transitions of intermediates was confirmed by X-ray diffraction at variable temperatures. The phase diagram exhibits also two plateaus at 429 K and 435 K corresponding to the phase transitions of CsNO3 and AgNO3, respectively.

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TheT — x phase diagram of the pseudobinary system PbTe-As2Te3 was constructed from DTA data and results of X-ray diffraction analysis and electron-probe microanalysis. No new compound was found in the system PbTe-As2Te3. The phase diagram of this system is of an eutectic type with an eutectic temperature of 350±5°, the eutectic composition corresponding to 10 mole% PbTe. Two solid phases with compositions near to As2Te3 and PbTe, respectively, coexist in the system below the eutectic temperature. The solubility of PbTe in As2Te3 is smaller than 2 mole% PbTe, and that of As2Te3 in PbTe is smaller than 0.5 mole% As2Te3 at 290°.

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Journal of Thermal Analysis and Calorimetry
Authors: V. Dvořák, V. Danielik, O. Matal, Marta Chrenková, and M. Boca

Abstract  

The phase diagram of the binary system NaF-SnF2 was determined by using the thermal analysis method. In addition to the crystallisation fields of pure components the formation of three other crystallisation fields was observed and these were attributed to the compounds: NaF·2SnF2, NaF·SnF2 and 2NaF·SnF2. The coordinates of the four eutectic points are: e 1: 70 mol% NaF, 30 mol% SnF2 and 255°C e 2: 58 mol% NaF, 42 mol% SnF2 and 238°C e 3: 44 mol% NaF, 56 mol% SnF2 and 246°C e 4: 18 mol% NaF, 82 mol% SnF2 and 191°C The model independent on the real structure of the melt was applied for the calculation of phase diagram comprising the calculation of excess molar Gibbs energy of mixing. The probable inaccuracy in the calculated phase diagram is σ=2.0°C. XRD analysis of solidified mixtures was performed in order to confirm the formation of expected compounds.

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Abstract  

Experimental results obtained by phase diagram investigation of Pb-In binary system are presented in the paper and compared with literature data. Liquidus and solidus temperatures, as well as cell parameters were determined, and structural analysis of this system was made. Microstructural analysis was done by SEM-EDX, crystallographic analysis was performed by diffractometry, while liquidus and solidus temperatures were determined by DTA. Obtained results show that in investigated system exist three areas: area reach in In, area reach in Pb and separating the intermediate phase (αIn). Experimental results show good agreement with literature.

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Abstract  

The Al-Zn-Ga ternary phase diagram was earlier established by thermodynamic modellization [1], but no experimental study appears to have been carried out on this system, except for measurements of mixing enthalpies in the liquid [2]. The present experimental study was carried out by thermal analysis and X-ray diffraction at various temperatures, using the isopletic cuts method. Four isopletic cuts were established and two others were partly studied in the Al-rich corner of the diagram. On these cuts, two isobaric ternary invariant reactions were determined: a eutectic reaction at 231C, and a metatectic reaction at 1231C. Evidence was found for the existence of a retrograde miscibility of Ga in a solid solution α′SS which protrudes into the ternary system starting from the Al-Zn binary up to a Ga concentration of about 30%*.

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Abstract  

The first part of this paper presented five experimental isopletic cuts in the Al-Zn-Ga ternary phase diagram. On these cuts, two isobaric ternary invariant reactions were determined and a significant retrograde miscibility of Ga in a α′SS solid solution was observed. In the second part, the two isobaric invariant reactions are studied more precisely. In particular, the composition of the invariant phases are given and the Ga miscibility in the αSS ternary solid solution is studied. Isothermal sections are established. The results confirm the existence of a vanishing point in the liquidus area, conjugated with a ternary critical point at about 290C. A general perspective shape of the equilibria in the diagram is proposed.

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Abstract  

The phase diagrams of four binary systems (C10H21NH3)2CoCl4−(C16H33NH3)2CoCl4, (C12H25NH3)2CoCl4−(C16H33NH3)2CoCl4, (C10H21NH3)2ZnCl4−(C16H33NH3)2ZnCl4 and (C12H25NH3)2ZnCl4−(C16H33NH3)2ZnCl4 were investigated by means of DSC. These six compounds and their binary mixtures can retain energies between 74 and 115 J/g during solid-state transformations at temperatures between 70 and 105°C, and they are therefore being considered for potential use in solar energy systems.

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Abstract  

It is well-known that eutectics do not necessarily grow at the eutectic temperature, or with the eutectic composition. Thus, the eutectic point can be shifted due to nonequilibrium conditions in the system. This fact was observed in many experiments. We try to explain this behaviour on base of the study of phase transformation kinetics. We construct the kinetic phase diagrams of PbCl2−AgCl within the framework as of the nucleation theory as of the theory of growth on the phase interface. Our models are based on the molecular model of the difference of chemical potential of components for the liquid and solid phases. The proposed model describes the position of the eutectic point very well and is practically applied for the study of nonequilibrium directional growth in the PbCl2−AgCl system.

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