Study Of Phase Equilibria Research Articles

Counterion-controlled phase equilibria in a charge-regulated polymer solution.

We study phase equilibria in a minimal model of charge-regulated polymer solutions. Our model consists of a single polymer species whose charge state arises from protonation-deprotonation processes in the presence of a dissolved acid, whose anions serve as screening counterions. We explicitly account for variability in the polymers' charge states. Homogeneous equilibria in this model system are characterised by the total concentration of polymers, the concentration of counter-ions and the charge distributions of polymers which can be computed with the help of analytical approximations. We use these analytical results to characterise how parameter values and solution acidity influence equilibrium charge distributions and identify for which regimes uni-modal and multi-modal charge distributions arise. We then study the interplay between charge regulation, solution acidity and phase separation. We find that charge regulation has a significant impact on polymer solubility and allows for non-linear responses to the solution acidity: Re-entrant phase behaviour is possible in response to increasing solution acidity. Moreover, we show that phase separation can yield to the coexistence of local environments characterised by different charge distributions.

Experimental and thermodynamic modeling study of phase equilibria in the PbO–NiO–SiO2 system

AbstractAn integrated experimental and thermodynamic modeling investigation of the phase equilibria in the PbO–NiO–SiO2 system in air and also in equilibrium with liquid metal has been undertaken to better characterize the chemical reactions taking place in the Ni‐containing Pb processing slags. New experimental phase equilibria data at 720°C–1740°C were obtained for this system using high‐temperature equilibration of synthetic mixtures with predetermined compositions in sealed silica ampoules or in Au/Pt–Ir foils, a rapid quenching technique, and electron probe x‐ray microanalysis of the equilibrated phase compositions. Phase equilibria and liquidus isotherms in the quartz/tridymite/cristobalite (SiO2), olivine (Ni2SiO4), monoxide (NiO), Ni‐barysilite (Pb8NiSi6O21), massicot (PbO), and di‐lead silicate (Pb2SiO4) primary phase fields were revealed and the extent of the high‐SiO2 two‐liquid immiscibility gap in equilibrium with cristobalite was determined. New experimental data were used in the development of a thermodynamic database describing this ternary system. Also, modeling revision of the NiO–SiO2 binary system was conducted, resulting in a smaller miscibility gap in ternary systems that was closer to the experimental results.

PHASE EQUILIBRIA IN THE SECTION Cu2Se – Cu3SbSe4

Complex selenides are promising thermoelectric materials in a wide temperature range. Since one of the methods for improving material parameters is the formation of solid solutions, the study of phase equilibria and the determination of the homogeneity regions of the components is relevant. This paper presents the results of a study of the physico-chemical interaction in the CuSe2 – Cu3SbSe4 system. The synthesis of alloys of the CuSe2 – Cu3SbSe4 system (0; 10; 30; 50% 70; 90; 100 mol. % Cu3SbSe4) was carried out by a direct one-temperature method at a maximum synthesis temperature of 1053 K. The obtained alloys were studied by X-ray phase, differential thermal and microstructural analyses. Based on the results of the analyses, it was found that CuSe2 – Cu3SbSe4 system is a partially quasi-binary section of the quasi-ternary Cu2Se–Sb2Se3–Se system. The section of CuSe2 – Cu3SbSe4 is characterized by the passage of four nonvariant processes. The studied section crosses the region of primary crystallization of the phase with congruent melting character - β-Cu2Se and the miscibility gap in liquid phase. The region of boundary solid solutions based on the initial components CuSe2 and Cu3SbSe4 does not exceed 5 mol.%.
 Keywords: selenides; phase diagram; thermal analysis; phase equilibria.

Phase equilibrium determination of the binary system globalide + pressured propane: Experiments and thermodynamic modeling

Globalide is a macrolactone used recently as a monomer in polymerization processes in several kinds of research due to its ability to produce biodegradable and biocompatible polyesters suitable for applications in biodegradable packaging and biomedical devices. Polymerization processes traditionally use organic solvents and metallic/chemical catalysts that may leave toxic residues in the final polymer. To obtain polymers free of organic solvents, the use of pressurized gases as green solvents has been investigated. In this context, knowing the phase behavior of these systems is essential to understand the proper conditions of the polymerization process, ensuring that the reaction occurs in single-phase conditions. This work reports phase equilibrium studies of Gl + propane systems at temperatures of 313.15, 323.15, 333.15, and 343.15 K, and propane mass fractions between 0.1 and 0.9001. All observed phase transitions occur in pressures lower than 2.5 MPa, indicating that propane is a solvent that requires less energy expenditure than systems with CO2, being an economic advantage in the polymerization process. Peng-Robinson equation of state with a constant binary interaction parameter adjusted adjustment to the experimental data well.

SURFACES OF CRYSTALLIZATION AND PHASE RELATIONS IN THE 6Ag2Se+Ag8SiTe66Ag2Te+Ag8SiSe6 RECIPROCAL SYSTEM

The paper presents the results of a study of phase equilibria in the 6Ag2Se+Ag8SiTe6 6Ag2Te+Ag8SiSe6 reciprocal system by DTA and XRD methods. The projection of the liquidus surface, isothermal sections at 300, 500, 1150 K, and some polythermal sections of the phase diagram are constructed. It is shown that the system is reversible-reciprocal. It is characterized by the formation of continuous high-temperature solid solutions along the Ag8SiSe6-Ag8SiTe6 () and Ag2Se-Ag2Te () boundary systems. It has been established that the liquidus surface of the reciprocal system consists of two fields of primary crystallization - and -phases. These surfaces are delimited by a eutectic curve with monovariant equilibrium L+. In the subsolidus part of the system, a complex interaction is observed associated with the polymorphism of the initial compounds and phases based on them

An experimental investigation of phase transformations in the Al-Fe-V system

This paper presents a comprehensive study of phase equilibria in the Al-Fe-V system by X-ray diffraction (XRD), scanning electron microscopy (SEM), differential thermal analysis (DTA) and electron probe microanalysis (EPMA). Liquidus and solidus projections, a number of isothermal and vertical sections, as well as a reaction scheme (Scheil diagram) are constructed. On the solidus surface, there is a continuous solid solution Al8(Fe,V)5 (Cu5Zn8-type structure, cI52-I-43 m), which decomposes with decreasing temperature. The limited solid solution formed in this case has the widest homogeneity region. At 1000 and 700 °C, the solubility of iron in it is 25 and 18 at.% Fe, respectively. The solidus surface is characterized by six three-phase fields: (Al) + Al13Fe4 + Al45V7, (Al) + Al21V2 + Al45V7, Al3V + Al23V4 + Al45V7, Al3V + Al45V7 + Al13Fe4, Al8(Fe,V)5 + Al3V + Al13Fe4 and Al8(Fe,V)5 + Al13Fe4 + Al5Fe2, which result from invariant four-phase equilibria. One of them is of the peritectic type, the others are of transition type. Equilibria take place at 653, ∼660, 735, 755, 1086, and 1121 °C, respectively. In the two-phase area AlFe + Al8(Fe,V)5 the solidus surface has a temperature minimum at 1188 °C, resulting from the invariant eutectic three-phase equilibrium L ⇄ AlFe + Al8(Fe,V)5. At ∼1080 and 730 °C, solid-state invariant four-phase equilibria Al8V5 + Al2Fe ⇄ AlFe + Al5Fe2 and Al8V5 + Al5Fe2⇄ AlFe + Al13Fe4, respectively, occur.

Phase equilibria in the Ag8SiSe6-Ag8SiTe6 system and characterization of the solid solutions Ag8SiSe6-xTex

Due to polymorphism and complex crystal structure, compounds of the argyrodite family and phases based on them exhibit several interesting functional properties, such as thermoelectric, photoelectric, optical, as well as ionic conductivity for Cu+ and Ag+ cations. The paper presents the results of the study of phase equilibria in the Ag8SiSe6-Ag8SiTe6 system by DTA, XRD, and SEM methods. Refined data on the melting temperature (1278 K) and polymorphic transitions (315 K and 354 K) of the Ag8SiSe6 compound are presented. The crystallographic parameters of LT-Ag8SiSe6 (Cubic, F-43m, a = 1.0965 nm) and IT-Ag8SiSe6 (Cubic, P4232, a = 1.0891 nm) are also determined. It has been established that the investigated system is quasi-binary and its phase diagram is characterized by the formation of a continuous series of substitutional solid solutions between HT-Ag8SiSe6 and Ag8SiTe6. This process is accompanied by a strong decrease in the temperatures of polymorphic transformations of Ag8SiSe6, which leads to the stabilization of the ion-conducting cubic phase at room temperature in the >10 mol% Ag8SiTe6 compositions area. The crystal lattice parameters of the synthesized solid solutions are calculated by indexing the powder diffraction patterns. The stabilization of the high-temperature cubic phase at room temperature achieved by us presents new opportunities for the development of environmentally friendly thermoelectrics and ion-electronic conductors based on silicon argyrodites with desired composition and properties.

6Ag2Se + Ag8GeTe6 ↔ 6Ag2Te + Ag8GeSe6 Reciprocal System

Here, we present the results of DTA and XRD studies of phase equilibria in the 6Ag2Se + Ag8GeTe6 ↔ 6Ag2Te + Ag8GeSe6 reciprocal system (system A). A Т–х diagram of the Ag8GeSe6–Ag8GeTe6 boundary system, several inner polythermal sections, isothermal sections at 300 and 1000 K, and the liquidus surface projection were plotted. The Ag8GeSe6–Ag8GeTe6 system is a partially quasi-binary system; it features continuous substitutional solid solutions between Ag8GeTe6 and the high-temperature cubic Ag8GeSe6 phase (the δ phase). Once solid solutions are formed, the polymorphic transition temperature in Ag8GeSe6 decreases, thereby stabilizing the ion-conducting cubic phase in the range of ≥40 mol % Ag8GeTe6 compositions at room temperature and below it. System A is shown to be a reversible reciprocal system; its liquidus surface is comprised of three fields, which relate to the primary crystallization of the solid solutions between the high-temperature Ag2Se and Ag2Te (α phase) phases, IT-Ag2Te-base solid solutions (β phase), and the δ phase. The subsolidus portion of system A features complex interactions related to polymorphism in the terminal compounds and in phases based on them

Phase equilibrium studies of Mo-Y2O3-ZrO2-Zr at 1200 ℃ for developing Y-Zr-O complex oxide dispersion-strengthened Mo alloys

Phase equilibria of the Mo-Y2O3-ZrO2-Zr section in the Mo-Y-Zr-O system at 1200 ℃ were studied for developing nanostructured Y-Zr-O complex oxide dispersion-strengthened Mo alloys and understanding the formation behavior of oxides. The evolution of intermetallic Mo2Zr and the powder composition of this Mo alloy during mechanical alloying (MA) were revealed. The results showed that the Mo-Y2O3-Zr section was confirmed by four kinds of two-phase regions (Mo) + αY2O3 and (βZr) + αY2O3 and three-phase regions (Mo) + αY2O3 + Mo2Zr and (βZr) + αY2O3 + Mo2Zr. These three-phase equilibria were associated with the four-phase equilibria of (Mo) + αY2O3 + Mo2Zr + (αZr) with a high concentration of O in (αZr). During MA, Mo2Zr was dissolved in the Mo matrix, and the introduced excess O and ZrO2 contaminants shifted alloy composition from Mo-Y2O3-Zr to Mo-Y2O3-ZrO2. The Mo-Y2O3-ZrO2 section was characterized by six kinds of two-phase regions Mo + βZrO2, Mo + γZrO2, Mo + Zr3Y4O12, and Mo + αY2O3, three-phase regions Mo + βZrO2 + γZrO2 and Mo + γZrO2 + Zr3Y4O12. The established Mo-Y2O3-ZrO2-Zr phase diagram suggests that the presence of excess Zr and insufficient O can bring about the formation of brittle Mo2Zr and Zr phase, and the Y/Zr ratio strongly determines the type of Y-Zr-O precipitates in Mo alloys.

Phase Equilibrium studies in the system “FeO”–SiO2–Al2O3–CaO–MgO at 1200 °C and Po2 10-8atm

Iron oxides and silica are the major components of copper smelting slag. The oxides of aluminum, calcium and magnesium are also present in the slag that is introduced through copper concentrate, flux and refractories. Liquidus temperatures of the copper smelting slags are usually controlled by Fe/SiO2. The concentrations of Al2O3, CaO and MgO, and FeO/Fe2O3 in the slag can also affect the liquidus temperatures where FeO/Fe2O3 is a function of oxygen partial pressure. High temperature equilibration under controlled oxygen partial pressure followed by quenching and electron probe microanalysis were used to determine the compositions of the liquid and solid phases at 1200 °C and Po2 10-8 atm. The experimental results are presented in the forms of pseudo-ternary sections “FeO”-CaO-SiO2 at fixed 2, 4 and 6 wt pct MgO, and 2 + 2, 4 + 4 and 6 + 6 wt pct MgO + Al2O3. Spinel and tridymite are the major primary phases in the composition range investigated. In addition, CaSiO3, pyroxene, olivine, and melilite are also present. The isotherms in the spinel and tridymite primary phase fields move towards higher SiO2 concentration directions with increasing CaO, Al2O3, and MgO concentrations. The experimentally determined results are compared with the FactSage calculations.

Phase Equilibrium Studies in the Geothermal Energy Development: The Effect of Hydrogen Bond on the Multi-Component Fluid.

Geothermal energy has become an emerging resource with both large reserves and environmental friendliness and is playing an increasingly important role in the current energy transition progress. In this paper, a thermodynamically consistent NVT flash model is developed to consider the effect of hydrogen bond on the phase equilibrium states of multi-component fluid to resolve the challenges of the special thermodynamic characteristic of water as the main working fluid. In order to provide practical suggestions to the industry, a number of possible effects have been investigated on the phase equilibrium states, including the hydrogen bond, environmental temperature, and fluid compositions. The calculated phase stability and phase splitting results can provide thermodynamic foundations for the establishment of the multi-component multi-phase flow model and also help optimize the development process to control the phase transitions for a number of engineering purposes.

Extractive desulfurization of thiophene by tetraethylene glycol at T = 298.15 to 313.15 K and liquid–liquid phase equilibrium study

ABSTRACT This study provides the complete liquid–liquid equilibrium (LLE) data including the solubility curves and tie-lines for heptane + thiophene + tetraethylene glycol and cyclohexane + thiophene + tetraethylene glycol ternary mixtures at 298.15–313.15 K under a pressure of 83.4 ± 1 kPa. The experimental data were obtained by the cloud point method. Type 1 phase behavior is observed for the systems. The observed behavior was interpreted based on the type and nature of the interactions between the components. The capability of tetraethylene glycol in extractive desulfurization of thiophene from liquid fuel is evaluated by determining the solute distribution coefficient and selectivity. The high values of the selectivity show that tetraethylene glycol is a good candidate for this purpose. The investigation of the effect of temperature on the area of the biphasic region and distribution ratios shows that the extraction process can be performed at room temperature. The experimental data were successfully correlated with the NRTL model. The reliability of the correlation results was checked by using a Graphical User Interface (GUI) for the representation of Gibbs energy of mixing (GM). The root mean square deviation (RMSD), a measure of the precision of the correlations, ranges from 0.0022 to 0.0040.

Deportment of Metals from E-Waste PCBs towards Alloy and Slag Phases during Smelting Using CaO-Al2O3-SiO2-B2O3 Slags

Printed circuit boards (PCBs) from antiquated electronic goods were processed by a pyrometallurgical route to produce and separate alloy and slag phases. The process involved initial size reduction of PCBs, followed by pyrolysis at 500 °C for 6 h and finally smelting of the solid materials in an electric furnace. A preliminary smelting test was performed at 1600 °C to estimate the composition of the slag generated. In later kilogram-scale smelting experiments, B2O3 flux was added along with CaO and SiO2 to decrease the liquidus temperature required to smelt the PCBs. The level of fluxing was adapted from earlier phase equilibria studies of the CaO-Al2O3-SiO2-B2O3 slag system. Results showed that the flux decreased the melting temperature and assisted the recovery of most valuable metals within the alloy phase at 1350 °C smelting temperature. The alloy phase recovered 99.8% of Cu, 99% of Sn, and 100% of precious metals (Au, Ag, Pt). A fluxing strategy for smelting high Al2O3 containing e-waste PCBs was proposed based on the experimental findings of this research.

Phase diagrams of zirconium dioxide systems with yttrium and scandium oxides

The literature data on the study of phase equilibria in systems zirconia with yttria and scandia are analysed. Possible schemes of low-temperature phase equilibria in ZrO2-Y2O3 and ZrO2-Sc2O3 systems are presented taking into account the third law of thermodynamics. The coordinates of non-variant transformations in these systems are tabulated. A sign of non-equilibrium states is the observation of non-diffusion processes of ordering of solid solutions. The modified cryoscopy method is used to calculate the distribution coefficients of scandia and yttria during the crystallization of the ZrO2 melt. The possibilities for the existence of a set of ordered phases in the ZrO2-Y2O3 system and diffuse phase transition in the cubic modification of zirconia are discussed.

Modeling of the Phase Assemblage of the LiF–Li2CrO4–LiRbCrO4–LiKCrO4 Stable Tetrahedron of the Li+, K+, Rb+||F–, Quaternary Reciprocal System

Here, phase equilibria in a quaternary reciprocal system comprised of fluorides and chromates of lithium, potassium, and rubidium was studied. The phase assemblage of the system was partitioned to stable simplices. The Li–Li2CrO4–LiRbCrO4–LiKCrO4 stable tetrahedron was selected as the subject matter of this study due to its undoubted scientific importance. The analysis of the boundary elements predicted, and the DTA experimental study of phase equilibria in the system proved, that monovariant phase equilibrium L ⇄ LiF + α-Li2CrO4 + (LiKxRb1 – xCrO4)ss is realized in the system, described by line Е 397–Е 400; the characteristics of the minimum point of this monovariant equilibrium (Min◻ 367) were elucidated. The mass balance of the phase reaction for this point is presented. A 3D model of the phase assemblage of the system was designed based on experimental data. The system preserves the continuity of (LiKxRb1 – xCrO4)ss solid solutions. The mixture whose composition corresponds to point Min◻ 367 has a relatively low melting temperature and can serve as a material for new fusible electrolytes in chemical current sources; it can also be of interest as an electrolytic bath for recovery of metals from melts.

Simulation prediction and experimental study of phase equilibria of Bi–Sb and Bi–Sb–Cd alloys in vacuum distillation

In this study, experimental determination and model prediction of the vacuum distillation vapor-liquid equilibrium (VLE) values of Bi–Sb binary alloy and Bi–Sb–Cd ternary alloy at different temperatures were undertaken under a vacuum of 1–5Pa. The experimental result shows that Bi and Sb were separated effectively from Bi–Sb binary alloy and Cd in Bi–Sb–Cd ternary alloy preferentially volatilized and entered the vapor phase completely. Combined with the above two-step experiments, the segmented distillation can purify crude antimony. The molecular interaction volume model (MIVM) was used to predict both the activity of each alloy element of Bi–Sb, Bi–Cd and Sb–Cd and VLE values. The average relative deviation of activity was <±5.19% compared with the adopted experimental values, and the VLE values were consistent with the trend of the experimental values. The MIVM was further used to predict the activity and VLE values of Bi–Sb–Cd ternary alloy, and the result corresponds with the experimental values. This combination of experiment and model prediction not only verified the reliability of the MIVM in predicting the activity and VLE values of antimony-based alloys, but also optimized their process parameters of vacuum distillation, providing theoretical guidance for vacuum distillation purification of crude antimony and further industrial experiments.

Actual chemical composition of 123-phase and revised phase diagram for the Y2O3 – BaO – Fe2O3 system

A systematic study of phase equilibria of the Y2O3 – BaO – Fe2O3 system in the vicinity of YBa2Fe3O8+δ reveals that the actual composition of the 123-type oxide differs from the ideal one. It is shown that a single-phase oxide with a 123-type structure can be obtained at 1373 ​K in air only with a slight deficit of Ba and an excess of both Y and Fe components. The overall formula of the single-phase 123-type oxide is written as Y1.05Ba1.92Fe3.03O8+δ. The composition of one more complex oxide, which is absent in the reported earlier phase diagram, is also found to be Ba-deficient; it can be presented as Y1.04Ba0.96FeO4. As a result, the revised version of phase diagram for the Y2O3 – BaO – Fe2O3 system is constructed at 1373 ​K in air.

Examination of eutectic phase change materials composed of diols and ionic liquids

This paper presents solid–liquid phase equilibrium studies of binary systems composed of pyridinium chloride monohydrates: hexadecylpyridinium chloride monohydrate, [PyC16][Cl] or dodecylpyridinium chloride monohydrate, [PyC12][Cl] with diols: 1,2-hexanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol and 1,12-dodecanediol. These systems were selected to obtain eutectic mixtures with a high melting enthalpy and lower volatility (thus flammability) than pure diols. Ten eutectic Phase Change Materials (ePCMs) with melting points ranging from 265 K to 333 K (-8 °C to 60 °C) and enthalpies of melting from 125.9 to 212.8 J·g−1 were obtained. Experimental data were then correlated with the Non-Random Two-Liquid (NRTL) equation, and mixtures of eutectic composition were subjected to physicochemical characterisation. Using DSC, the latent heats of pure components and eutectic mixtures were determined, as well as the viscosity and the thermal conductivity of ePCMs was measured as a function of temperature. The final objective of the study was to increase the thermal conductivity of ePCMs by adding carbon nanotubes or expanded graphite, and to characterise the performance of such composite systems. The stability of nanofluids containing no less than 1 wt% SWCNTs and from about 10 wt% EG was confirmed under both isothermal and energy storage operating conditions, i.e. during a series of at least 1000 phase transformations. The addition of an inexpensive EG at 10 wt% increases the thermal conductivity by up to 200 % and reduces the probability of ePCM leakage as the material retains its shape even after melting.

Phase equilibrium modelling of partial melting in the upper mantle: A comparison between different modelling methodologies and experimental results

Recent advances in thermodynamic modelling now allow phase equilibrium studies of partial melting in mafic and ultramafic sources under upper mantle conditions. This potentially offers several advantages over experimental investigations, including the fact that capsule-sample interactions are avoided, there is no uncertainty over the volatile content of the charge, the process is much faster, and open system behaviour can be investigated with relative ease. Two different thermodynamic datasets are in common use for phase equilibrium investigations of mantle rocks, compiled alongside a range of constantly evolving phase solution models. This study compares the results of published experimental studies on partial melting in the upper mantle with phase equilibrium modelling results from the popular pMELTS software (Ghiorso et al., 2002), which uses an embedded dataset from Berman (1988), and with results from the Rcrust software (Mayne et al., 2016), which uses the dataset of Holland & Powell (2011). The aim of this comparative study is to investigate the suitability of each combination of software specific calculation routines, thermodynamic datasets and phase solution models to provide a viable alternative to conventional experimental techniques when studying magma genesis from the upper mantle. The main points of interest are how the phase assemblages, proportions, and compositions predicted by the modelling compare with those produced in the experiments. The set of experimental results used for comparison includes both peridotitic and eclogitic compositions, investigated over a pressure range of 1.0–3.0 GPa and a temperature range of 1165–1950 °C. The results indicate that using the Holland & Powell (2011) dataset and appropriately selected phase solution models provides the best match with experimental results in terms of melt volume, melt composition and the assemblage of coexisting phases produced during partial melting under upper mantle conditions.

Phase Equilibrium Studies in the CaO–SiO2–Al2O3–MgO System with MgO/CaO Ratio of 0.2

With the raw materials for ironmaking are becoming increasingly complex, more accurate control of blast furnace operation is essential to reduce the energy cost and CO2 emission. CaO–SiO2–Al2O3–MgO is a basic system of ironmaking slag in which CaO and MgO are mainly come from the flux, SiO2 and Al2O3 are mainly from the raw materials. Effect of raw material composition on phase equilibrium of the slag can be described by a pseudo-ternary system (CaO + MgO)–SiO2–Al2O3 at a fixed MgO/CaO ratio of 0.2. High-temperature experiments have been carried out in this system, and the quenched samples were analyzed by an electron-probe microanalyzer. The results are presented in a pseudo-ternary phase diagram (CaO + MgO)–SiO2–Al2O3 with a fixed MgO/CaO weight ratio of 0.2. Dicalcium silicate (Ca2SiO4), Melilite (2CaO·MgO·2SiO2–2CaO·Al2O3·SiO2), spinel (MgO·Al2O3), merwinite (3CaO·MgO·2SiO2), and anorthite (CaO·Al2O3·2SiO2) are the major primary phases in the composition range investigated. A series of pseudo-binary phase diagrams have been constructed to demonstrate the applications of phase diagram on blast furnace operation. CaO-rich cordierite solid solution has been first time reported with the accurate compositions and microstructure. The liquidus temperatures and solid solution compositions are compared between the experimental data and FactSage predictions to provide useful information for optimization of the thermodynamic database.