Search

Copper-tin and copper-antimony chalcogenides have received increasing attention as promising thermoelectric materials due to their high efficiency and low toxicity. Many of these phases are synthetic analogues of natural copper chalcogenide minerals and have been drawing more interest for the development of new environmentally friendly materials. In this regarding, we studied phase equilibria in the Cu2Se - Cu3SbSe4 - Cu2SnSe3 system using Differential Thermal Analysis (DTA), Powder x-ray Diffraction (PXRD) and Scanning Electron Microscope (SEM). Based on experimental data, a number of polythermal sections, the solid-phase equilibria diagram at 600 K and a projection of the liquidus surface were constructed for the title system. The system has revealed limited regions of solid solutions based on ternary compounds Cu3SbSe4 (α) and Cu2SnSe3 (β). It has been established that the liquidus surface consists of three regions corresponding to primary crystallization (HT-Cu2Se), as well as α- and β-phases. [ABSTRACT FROM AUTHOR]

The system BaO–TiO2 is technically important because it contains multiple dielectric and ferroelectric phases, including the important BaTiO3, which is one of the most widely studied dielectric perovskites owing to its dual piezoelectric and ferroelectric properties. The present work revises the subsolidus phase equilibria data by synthesizing previous phase equilibria data and new experimental results using high‐temperature (600°–1300°C) and long‐term (≤336 h) equilibration, coupled with analytical work based principally on room‐temperature X‐ray diffraction. The resultant phase diagram is given in both mole and weight percents, extending from the liquidus surface (not investigated) to absolute zero temperature (for inclusion of the previously excluded crystallographic and ferroelectric phase transformations). The major features include (1) correction of four eutectoid and three peritectoid reactions and corresponding temperatures, (2) indication of inferred partial solid solubilities, (3) clarification of the BaTiO3 solid solubility homogeneity regions, and (4) specification of some invariant point compositions on the liquidus surface. [ABSTRACT FROM AUTHOR]

The system BaO–TiO2 is technically important because it contains multiple dielectric and ferroelectric phases, including the important BaTiO3, which is one of the most widely studied dielectric perovskites owing to its dual piezoelectric and ferroelectric properties. The present work revises the subsolidus phase equilibria data by synthesizing previous phase equilibria data and new experimental results using high‐temperature (600°–1300°C) and long‐term (≤336 h) equilibration, coupled with analytical work based principally on room‐temperature X‐ray diffraction. The resultant phase diagram is given in both mole and weight percents, extending from the liquidus surface (not investigated) to absolute zero temperature (for inclusion of the previously excluded crystallographic and ferroelectric phase transformations). The major features include (1) correction of four eutectoid and three peritectoid reactions and corresponding temperatures, (2) indication of inferred partial solid solubilities, (3) clarification of the BaTiO3 solid solubility homogeneity regions, and (4) specification of some invariant point compositions on the liquidus surface. [ABSTRACT FROM AUTHOR]

BiFeO3 and EuFeO3 are some of the most studied ferrites and part of the larger category of multiferroic and magnetic compounds. The instabilities reported for BiFeO3 that hinder its use in practical applications can be overcome by substitution with rare-earth ions, such as Eu3+, on the Bi3+ site. This paper reports on the phase relations in the BiFeO3-EuFeO3 pseudo-binary system, which were not established previously. Solid-state reactions were employed to prepare different compositions according to the nominal formula Bi1−xEuxFeO3 (where x = 0, 0.05, 0.10, 0.15, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1). Phase equilibria were studied at different temperatures between 800 and 1200 °C from X-ray diffraction (XRD) data. The analysis of the XRD patterns by machine learning approaches revealed eight defined clusters and four unclustered points. The validation test showed that most of the points could belong to several clusters and thus, traditional identification was employed. Phase identification and quantification by traditional approaches revealed six crystallization zones on the diagram. Although the machine learning approach offers speed in the process of classification of XRD patterns, validation by the traditional method was necessary for the construction of the phase diagram with high accuracy. [ABSTRACT FROM AUTHOR]

Despite the importance of Al and Ta as alloying elements for Co- and Ni-base alloys, there has been limited research on the phase equilibria in the Al-Co-Ta and Al-Ni-Ta systems. Additionally, the available data are sparse and sometimes inconsistent due to the peculiar experimental challenges of these systems. Based on that, a comprehensive and critical evaluation of their phase equilibria is useful in view of further experimental and computational studies. Within this framework, the Al-Co-Ta and Al-Ni-Ta ternary systems and the respective binary subsystems are here critically assessed. All available literature investigations are analyzed and as a result, a set of self-consistent diagrams and tables are presented, reporting crystal structure data, liquidus projections, isothermal sections, etc. [ABSTRACT FROM AUTHOR]

Thermodynamic databases are indispensable in providing phase equilibria and phase transformation for new alloys design and process optimization. The quality of calculated results is strongly dependent on the accuracy of the thermodynamic database. A thermodynamic database for multicomponent copper alloys has been developed, which contains 30 elements covering the major and minor alloying elements of most commercial copper alloys. About 330 binary and 60 ternary systems have been assessed over the entire composition range. Examples of assessments and calculations for typical binary and ternary systems were presented. A wide range of compositions from pure copper to complex commercial copper alloys can be calculated. Scheil solidification simulations were carried out using the thermodynamic database for predicting the phase formation sequence during solidification, as well as phase compositions and phase fractions. In conjunction with a compatible kinetic database, the present established thermodynamic database was used to simulate the microstructure evolution of copper alloys during the ageing process. The simulated results were verified by key experiments, which proves the accuracy of the thermodynamic database established by us. [ABSTRACT FROM AUTHOR]

The K2O‐Al2O3‐SiO2 system is an important component of microcrystalline glass. The K2O‐Al2O3 and K2O‐SiO2 binary systems and the K2O‐Al2O3‐SiO2 ternary system were thermodynamically evaluated and optimized using the CALculation of PHAse Diagram (CALPHAD) method. The liquid phase is described by using the ionic two‐sublattice model, and the solid solutions involved in the ternary system are all described using the compound energy formalism (CEF) model. The new parameters obtained from the optimization are capable of describing the equilibrium phase relations of the ternary system and its subsystems, and the calculated thermodynamic properties of the ternary compounds are in good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

Copyright of Nonferrous Metals (Extractive Metallurgy) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Phase equilibria in the ZrO2–YO1.5–NbO2.5 system were experimentally studied at 1300°C, and a comparison with the existing ZrO2–YO1.5–TaO2.5 (ZYTO) was conducted. Ternary fluorite phases on the Y:Nb > 1 side extend from binary ZrO2‐YO1.5 to YO1.5–NbO2.5 system, generating a continuous solid solution region. Furthermore, it was observed that three phases of M‐YNbO4, fluorite, and m‐ZrO2 were in equilibrium. On the Y:Nb < 1 side, two three‐phase equilibrium regions were measured, namely M‐YNbO4+m‐ZrO2+O‐Nb2Zr6O17 and h‐Nb2O5+O‐Nb2Zr6O17+M‐YNbO4. The tetragonal YNbO4 and ZrO2 phases both extend nearly along with Y:Nb = 1. The t‐ZrO2 phases with slightly lower stabilizer content were found to transform into their monoclinic polymorph during the cooling process. However, in the ZrO2–YNbO4 subsystem, the tetragonal ZrO2 was nontransformable due to larger YO1.5 and NbO2.5 co‐dopants, and the maximum solubility is about 18.1 mol%. Upon cooling, the tetragonal YNbO4 phase, even with the maximum ZrO2 content, is transformable to monoclinic form. The maximum solubility of ZrO2 in YNbO4 is determined to be about 20.7 mol%. Finally, the high‐temperature liquidus in the ZrO2–YNbO4 system was first determined based on the cooling traces, and a vertical section diagram was proposed for further speculation. A eutectic reaction of Liquid→YNbO4+ZrO2 was discovered, and the eutectic composition and temperature were measured as 39.2ZrO2–29.2YO1.5–31.6NbO2.5 and 1813°C. This study provides the basis for thermodynamic assessment of ZrO2–YO1.5–NbO2.5 and is valuable for the design and development of the ZrO2–YO1.5–NbO2.5‐based ceramic materials. [ABSTRACT FROM AUTHOR]

A long-term foundational study aimed at developing a thermodynamic database for continuous basalt fiber systems is in progress. In this work, the equilibrium phase relations of the SiO 2 –Al 2 O 3 –Fe 3 O 4 -5 wt.% CaO system at 1400 °C in air atmosphere were determined experimentally using the equilibrium-quenching technique. Subsequent analyses were conducted using Electron Probe Micro-Analysis (EPMA), X-ray Diffraction (XRD), and Scanning Electron Microscopy (SEM) to validate the experimental results and further investigate the microstructural characteristics. The results revealed a single liquid region and three distinct two-phase regions as Liquid-Cristobalite, Liquid-Mullite solid solution, and Liquid-Spinel solid solution. Additionally, two three-phase regions were identified as liquid-cristobalite-mullite solid solution, and liquid-mullite solid solution-spinel solid solution. This work contributes to a deeper understanding of the phase behavior during the melting of basalt ore systems, which is crucial for optimizing their production and enhancing their applications. [ABSTRACT FROM AUTHOR]

Existing thermodynamic descriptions of the whole Cr–Fe–P system are insufficiently accurate for understanding the thermodynamic behavior of the Cr–Fe–P materials during the manufacturing process. To construct a more precise and consistent thermodynamic database of the Cr–Fe–P system, thermodynamic modeling of the Cr–P and Cr–Fe–P systems was conducted using the CALculation of PHAse Diagrams (CALPHAD) approach based on critical evaluation of the experimental data. The modified quasichemical model and compound energy formalism were employed to describe the liquid and solid solutions, respectively. The Gibbs energies of stoichiometric compounds Cr3P(s), Cr2P(s), CrP(s), and CrP2(s) were carefully determined based on reliable experimental data. The ternary (Cr,Fe)3P, (Cr,Fe)2P, and (Cr,Fe)P phosphides were modeled as solid solutions considering mutual substitution between Cr and Fe atoms. In addition, the phase equilibria of BCC_A2 and FCC_A1 solutions and the liquid phase of the ternary Cr–Fe–P system were also optimized for more accurate descriptions of existing phase equilibria and thermodynamic properties data. As an application of the present database, the experimentally unexplored thermodynamic properties and phase diagrams of the Cr–Fe–P system are predicted. [ABSTRACT FROM AUTHOR]

The Na2O‐SiO2‐TiO2 system is important for the glass, ceramic, and metallurgical industries. Its features provide information on the composition and melting temperature to be utilized during the production of glass and ceramic and during the processing of TiO2‐bearing material in the metallurgical industry. The liquidus temperatures between 900 and 1600°C in the ternary system at saturation of solid SiO2, TiO2, Na2Ti6O13, Na2SiTiO5, and Na2Ti3O7 were measured using the equilibration‐quenching energy‐dispersive X‐ray spectroscopy/Electron Probe Microanalyzer technique. A wide range of liquidus compositions were obtained with Na2O between 0 and 41.7 mol% in the SiO2‐ and TiO2‐rich regions. The present study provides liquidus data at 1500 and 1600°C for the first time. Liquidus temperatures at various double saturations were also obtained in the present investigation to determine univariant lines in the phase diagram. The present experimental data were compared with previous investigations and computed phase diagrams. The data obtained in the present investigation can be employed to optimize the thermodynamic properties and phase diagrams of the Na2O‐SiO2‐TiO2 system. [ABSTRACT FROM AUTHOR]

The 1773 K phase diagram of the TiO 2 –SiO 2 –CaO-10 wt%Al 2 O 3 -7.5 wt%MgO system was constructed experimentally using the quenching method, focusing on the composition range of high TiO 2 content. The obtained isothermal section contains four phase fields: the liquid phase field, the primary phase field of pseudo-brookite, the primary phase field of perovskite, and the liquid + perovskite + pseudo-brookite phase field. The pseudo-brookite particle precipitated in its primary phase field is more suitable for the efficient selective enrichment and separation of titanium resources. The increase of MgO from 5 % to 7.5 % in the TiO 2 –CaO–SiO 2 -10 wt%Al 2 O 3 –MgO system leads to a decrease of the liquidus temperature and an expansion of the liquid + pseudo-brookite + perovskite phase field. The increase of MgO promotes the enrichment of TiO 2 into the pseudo-brookite phase and reduces the TiO 2 level in the glass phase. [ABSTRACT FROM AUTHOR]

With the rapid advancement of the new energy industry, porous electrode materials and complex electrolytes have gained widespread usage. Electrolytes exhibit distinctive phase behavior when subjected to the combined influence of confined space and electric fields. However, the measurement and prediction of such phase behavior encounter significant challenges. Consequently, numerous theoretical tools have been employed to establish models for phase equilibrium calculations. Nevertheless, current research in this field has notable limitations and fails to address the confinement of space or complex polymer electrolytes. Considering these shortcomings, an associating polymer density functional theory (PDFT) was developed by modifying excess free energy. This study examines the phase behavior of electrolytes with various chain lengths within diverse confined slits, revealing that the confinement effect and fluid tail chains can narrow the phase diagram. Additionally, a linear correlation between the electric field strength and the phase equilibrium offset has been identified, and a quantitative relationship is derived. The results of this investigation contribute to a deeper comprehension of complex fluid phase behavior and guide the design of electrochemical devices. [ABSTRACT FROM AUTHOR]

In this work, the phase equilibria of the binary Ag-In system were determined using electron probe microanalysis and differential scanning calorimetry on equilibrated alloys and diffusion couples. The compositions of the phase boundaries of solid phases that are highly scattered in the literature have been precisely determined. The temperatures of the invariant reaction ζ ⇄ γ + L and the polymorphic transformation ζ ⇄ γ are substantially lower than previously reported values. In addition, it was found that the In-rich ζ phase phase-separates after months of room-temperature aging. [ABSTRACT FROM AUTHOR]

Through experimental study of carefully crystallized via long-term thermal annealing alloys using powder X-ray diffraction and differential thermal analysis methods, as well as considering the evidence from the literature, a comprehensive picture of phase equilibria in the Cu2Se-Cu3AsSe4-As2Se3 system was obtained. The projection of the liquidus surface, the isothermal section at 500 K, and three vertical sections of the phase diagram are presented and discussed. The fields of primary crystallization of phases, types, and coordinates of invariant and monovariant phase equilibria are determined. The side Cu2Se-As2Se3 system was re-investigated and its refined phase diagram was constructed. It is shown that this system is quasi-binary and is characterized by the formation of ternary Cu3AsSe3 and CuAsSe2 compounds. [ABSTRACT FROM AUTHOR]

Phase equilibria were investigated between 200 and 800 °C in the Cu-Zn binary system. Wavelength dispersive spectroscopy (WDS) was performed to determine the equilibrium compositions, and differential scanning calorimetry (DSC) was performed to investigate the solidus and liquidus temperatures and the invariant reaction temperatures of the Zn-rich portion. The β/(α + β) boundary in the Cu-rich portion extended toward the Cu-rich side as the temperature decreased below the A2–B2 order–disorder transformation temperature, and the phase boundaries of the γ, δ and ε phases shifted toward the Cu-rich side. The liquidus temperatures of the ε + liquid were higher than those of the previous report. From the experimental results, the phase diagram of the Cu-Zn binary system was determined in the whole composition range. [ABSTRACT FROM AUTHOR]

Here, a complete phase equilibria picture in the Cu-As-S system was obtained by experimental study of carefully crystallized via long-term thermal annealing alloys by means of methods of differential thermal analysis and powder x-ray diffraction, as well as using the available literature data. The projection of the liquidus surface, the isothermal section at 300 K, and some vertical sections of the phase diagram are presented and discussed. The fields of primary crystallization of phases, types, and coordinates of invariant and monovariant phase equilibria are determined. The presented phase diagram reflects four ternary compounds Cu3AsS4, Cu12As4S13, Cu6As4S9, and CuAsS, which are synthetic analogues of natural copper-arsenic sulfide minerals. Particular attention is paid to the Cu2S-As2S3 section. It is shown that this section, in contrast to the literature data, is not quasi-binary. The thermodynamic data for copper-arsenic sulfides, previously obtained by the authors by the electromotive force method with Cu4RbCl3I2 solid electrolyte, have also been revised. Experimental data on the partial thermodynamic functions of copper in some phase regions of the Cu-As-S system were processed taking into account the constructed new version of the solid-phase equilibria diagram and updated data on the standard thermodynamic functions of formation and standard entropies of the ternary compounds Cu3AsS4, Cu12As4S13, Cu6As4S9, and CuAsS were obtained. [ABSTRACT FROM AUTHOR]

The phase diagram of the Fe-Zn binary system was evaluated based on the CALPHAD method with reference to the latest experimental data. The solubility ranges of the intermetallic compound phases, Γ-Fe4Zn9, Γ1-Fe11Zn40, δ1k-FeZn7, δ1p- Fe13Zn126, and ζ-FeZn13 were modeled considering their structures consisting of Zn12 icosahedra with Fe at the center (Fe1Zn12 clusters) as well as glue-like Fe and Zn atoms, and the miscibility gap between the δ1k and δ1p phases was also taken into account in the present calculations. The solubility of Fe in the liquid and (ηZn) phases that was confirmed as dozens of times larger than the values reported in the earlier literature could be calculated by introducing Fe1Zn12 associates to these solution phases. Consequently, all phase equilibria were adequately reproduced by the thermodynamic models and parameters revised in the present study. [ABSTRACT FROM AUTHOR]

Heavy p-elements-rare earth element tellurides are important multifunctional materials with thermoelectric, magnetic, optical, topological insulating, and other properties. This paper presents the results of a study of phase equilibria in the Tl2Te-TlBiTe2-TlGdTe2 system and the magnetic properties of the TlBi1−xGdxTe2 solid solutions. A diagram of solid-phase equilibria of the indicated system has been constructed. According to the data obtained, it is characterized by the formation of wide areas of homogeneity based on the initial compounds of the TlBiTe2-TlGdTe2 boundary system and a continuous series of solid solutions along the Tl9BiTe6-Tl9GdTe6 section (δ-phase). It has been shown that the homogeneity regions of the TlBiTe2 (β1) and TlGdTe2 (β2) compounds form a narrow (1-2 mol.%) band extending to 35 and 10 mol.% TlGdTe2 and TlBiTe2, respectively, along the boundary TlBiTe2-TlGdTe2 system while the homogeneity area of the δ-phase significantly extends into the compositions region rich in Tl2Te. Based on powder diffraction patterns, the phase compositions of the alloys and the crystallographic parameters of the identified solid solutions were determined. The work also presents several polythermal sections, isothermal sections at 760 and 800 K of the phase diagram, as well as a projection of the liquidus and solidus surface of the Tl2Te-Tl9BiTe6-Tl9GdTe6 subsystem. Magnetic properties of TlBi1−xGdxTe2 samples were investigated by magnetization and Electron Paramagnetic Resonance (EPR) measurements. It was found that these samples behave as a Curie-Weiss paramagnet containing Gd3+ ions with no indications of magnetic ordering or freezing down to 2 K. [ABSTRACT FROM AUTHOR]

The paper analyzes the works of the last decade on the study of ionic conductivity, thermoelectric, photovoltaic, photocatalytic, optical, etc. properties of the argyrodite family compounds (prototype Ag8GeS6), as well as phases and composite materials based on them. Considered works allow us to characterize them as valuable environmentally friendly functional materials with great potential for practical application. The main approaches which have been used in these works to enhance functional properties, as well as to improve the application capabilities of this class of substances have been analyzed. The importance of further systematic investigations on their design based on the "composition-structure-property" relationship has been noted. In the present review, special attention is paid to the analysis of works on phase equilibria in the corresponding systems since the information accumulated in phase diagrams is extremely important for optimizing the properties of compounds through targeted variation of composition and structure. Available data on the phase equilibria and thermodynamic properties of ternary and quaternary systems forming Cu/Ag argyrodite compounds and solid solutions based on them are presented and analyzed. It has been shown that anionic and Cu ↔ Ag substitutions in compounds lead to a strong decrease in their polymorphic phase transition temperatures and an expansion of the temperature-composition ranges of the existence of high-temperature ion-conducting phases up to room temperature and below. The possibility of replacing part of the chalcogen atoms in the compounds with halogens, and the Cu(Ag) atoms with elements of the zinc subgroup, which expands the range of argyrodite phases is also shown. The significance of expanding studies of phase equilibria and thermodynamic properties of these systems, especially five-component and more complex systems possessing a big possibility of the formation of high-entropy argyrodite phases, which have thermodynamic stability in a wide temperature-composition range and better applied characteristics has also been specified. [ABSTRACT FROM AUTHOR]

The content of iron oxides has a large impact on the properties of magnesium refractories, knowledge about the thermodynamic equilibria of the FeO–Fe2O3–MgO system is important for the design of refractory materials and resource utilization of solid wastes. The phase equilibria and thermodynamic data of the FeO–Fe2O3–MgO system have been critically evaluated and re‐optimized using the CALPHAD method. The ionic two‐sublattice model (Fe+2, Mg+2)P(O−2, Va, FeO1.5)Q was used to describe the liquid phase. A set of self‐consistent thermodynamic model parameters is presented to describe the phase equilibrium of the FeO–Fe2O3–MgO system. The calculated phase diagrams and thermodynamic properties, employing the optimized model parameters, exhibit excellent agreement with the experimental data. Moreover, the results demonstrate improved consistency when extrapolated to the multicomponent system, such as CaO–MgO–FeO–Fe2O3 and SiO2–MgO–FeO–Fe2O3 systems. The present thermodynamic modeling is useful to construct multicomponent oxide thermodynamic database and to guide the utilization of solid waste resources. [ABSTRACT FROM AUTHOR]

Phase equilibria studies were performed in the Li2O-SiO2 system for heat-treated samples using Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD). The temperature of the eutectic reaction (Liq. ⇌ Li4SiO4 + Li2SiO3) was experimentally determined at 1289 K using Differential Thermal Analysis (DTA). No evidences of the Li6Si2O7 formation was found by the experimental investigation and therefore, it was not considered. Heat capacity of the Li8SiO6 phase was measured using Differential Scanning Calorimetry (DSC). Solid phases of the Li2O-SiO2 system were described as stoichiometric compounds and liquid phases by two-sublattice partially ionic liquid model. Four stoichiometric intermediate compounds were considered to be stable (Li8SiO6, Li4SiO4, Li2SiO3 and Li2Si2O5). The polymorphic transformation in Li2Si2O5 phase was accounted and the metastable liquid miscibility gap on SiO2-rich side was reproduced. The calculated phase diagram satisfactorily agrees with the experimental phase equilibria as well as calculated thermodynamic properties reproduces experimental values within uncertainty limits. [ABSTRACT FROM AUTHOR]

When the calculation of phase diagram (CALPHAD) method is applied to the Au-Ag-Al ternary phase diagram, the accuracy of three marginal binary phase diagrams (Au-Al, Au-Ag, Ag-Al) has a great impact on the calculating results. At present, there are some contraditions in the Au-Al marginal binary phase diagram. Therefore, based on a comprehensive evaluation of experimental data for the Au-Al system, the equilibrium phase diagrams were optimised and calculated by using a solid solution model to describe the Gibbs free energy of the liquid, Bcc and Fee phases in the Au-Al system, and by using the sublattice models (Al)(Au)4, (Al)3(Au)8, (Al)(Au)2, (Al)(Au) and (A1,AU)2(A1,AU) to describe the A1AU4, Al3Au8, A1AU2, AlAu and AL2Au phases. A set of reasonably self-consistent thermodynamic parameters was obtained via optimizing with Pandat software. Au-Al phase diagrams calculated in this way agreed well with the experimental and thermodynamic data. Combined with thermodynamic parameters of Au-Ag and Ag-Al, the Au-Ag-Al liquid-phase, surface projections and isothermal cross-sections were calculated. The liquid- phase surface projections revealed the existence of eight four-phase equilibrium reactions in this ternary system, and these results may be helpful in studying the Au-Ag-Al alloys. [ABSTRACT FROM AUTHOR]

Knowledge about the thermodynamic equilibria of the P2O5-Na2O and P2O5-MgO systems is very important for controlling the phosphorus content of steel materials in the process of steelmaking dephosphorization. The phase equilibrium and thermodynamic data of the P2O5-Na2O and P2O5-MgO systems were critically evaluated and re-assessed by the CALPHAD (CAlculation of PHAse Diagram) approach. The liquid phase was described by the ionic two-sublattice model for the first time with the formulas (Na+1)P(O−2, PO3−1, PO4−3, PO5/2)Q and (Mg+2)P(O−2, PO3−1, PO4−3, PO5/2)Q, respectively, and the selection of the species constituting the liquid phase was based on the structure of the phosphate melts. A new and improved self-consistent set of thermodynamic parameters for the P2O5-Na2O and P2O5-MgO systems was finally obtained, and the calculated phase diagram and thermodynamic properties exhibited excellent agreement with the experimental data. The difference in the phase composition of invariant reactions from the experimentally determined values reported in the literature is less than 0.9 mol.%. The present thermodynamic modeling contributes to constructing a multicomponent oxide thermodynamic database in the process of steelmaking dephosphorization. [ABSTRACT FROM AUTHOR]

The phase equilibria in the Al-Ta-V ternary system at 1000 °C and 1200 °C have been studied by using electron probe microanalysis and x-ray diffraction. τ-Al2.9Ta2.7V1.4 phase was found in the Al-Ta-V ternary system in both isothermal sections. The addition of V stabilizes the Al69Ta39 phase at 1000 °C. The line compound Al3(V,Ta) (D022-type) forms a continuous phase region from the Al-V side to the Al-Ta side at the two temperatures. Based on our experimental results, reported liquidus projection of the ternary Al-Ta-V system and thermodynamic data of the binary systems of Al-V, Al-Ta and V-Ta, a thermodynamic evaluation of Al-Ta-V system was carried out by CALPHAD method. A set of reliable thermodynamic parameters for the Al-Ta-V system was obtained. The current calculation results agree well with the available experimental data. The invariant reaction scheme of Al-Ta-V ternary system was presented. The present study could provide essential experimental and thermodynamic data for establishing a comprehensive Co-based superalloy database. [ABSTRACT FROM AUTHOR]

Results are presented from an experimental study of the phase equilibrium (PTxy dependence) of an n-octadecane–propane/n-butane system for three isotherms (403.15, 423.15, 443.15 K) in the 0.89–7.24 MPa range of pressures using a high-pressure optical cell. The PTxy data are used to determine critical parameters of a mixture with identical concentrations of the two phases (x = y at fixed P and T). [ABSTRACT FROM AUTHOR]

The phase equilibria of the ZnO-"FeO 1..5 ", ZnO-"FeO 1.5 "-SiO 2 , PbO–ZnO-"FeO 1.5 " and PbO–ZnO-"FeO 1.5 "-SiO 2 slag systems in equilibrium with air or metallic lead/iron were studied as part of the investigation of the 19-component PbO–ZnO–Cu 2 O–FeO–Fe 2 O 3 –CaO–SiO 2 –Al 2 O 3 –MgO–S-(As, Sn, Sb, Bi, Ag, Au, Ni, Cr, Co as minor elements) slag/matte/metal/speiss/gas system, supporting the operation/development of existing and emerging pyrometallurgical processes. In the experimental part of the study, samples underwent high temperature equilibration followed by quenching, and the direct measurement of the lead, zinc, iron and silicon concentrations in the liquid slag, solid oxide, and metal phases by electron probe microanalysis (EPMA). The a) massicot (PbO), b) spinel ((Zn, Fe)Fe 2 O 4), c) zincite ((Zn,Fe)O 1+x , 2 polymorphs), d) lead ferrite (Pb 2+x Fe 2 O 5+x), e) plumboferrite (Pb 4 Fe 22-x Zn x O 37), f) magnetoplumbite (Pb(Fe 2 O 3 ,PbFeO 2 ,PbZnO 2)Fe 10 O 16), and g) W-ferrite (PbZn 2-x Fe 16+x O 27) primary phase fields of the PbO–ZnO-"FeO 1.5 " system in equilibrium with air were studied between 780 and 1300 °C. The ZnO-"FeO 1.5 ", ZnO-"FeO 1.5 "-SiO 2 and PbO–ZnO-"FeO 1.5 "-SiO 2 systems in equilibrium with air were studied up to 1745 °C, significantly improving the availability of information on the composition range of the high- and low-Fe zincite ((Zn,Fe)O 1+x) phases, and on the liquid slag composition at the boundaries of their primary phase fields. Lastly, the solubilities of iron in larsenite (Pb(Zn,Fe)SiO 4) and melilite (Pb 2 (Zn,Fe)Si 2 O 7) in equilibrium with air or metal were studied between 700 and 800 °C. The newly obtained and existing experimental data were used to develop a self-consistent set of thermodynamic parameters describing all phases in the system using the FactSage computer package. [ABSTRACT FROM AUTHOR]

Samarium monosulfide, a strain gauge and barometric material, exists in equilibrium with Sm3S4 and Sm2O2S in the S-Sm–O system. Therefore, studying phase equilibria in the refractory Sm2S3-X-SmS-Sm2O2S system is a scientifically interesting task. In this system, 49 samples were synthesized and studied by powder XRD, differential scanning calorimetry, visual thermal analysis, and microstructural analysis. Melting points of Sm3S4, SmS, and Sm2O2S compounds were determined. Eutectic diagrams of Sm3S4-Sm2O2S, SmS-Sm2O2S, SmS-Sm3S4 systems were constructed. Temperatures and compositions of the binary eutectic points were determined. Fusion enthalpies for Sm3S4, SmS, and Sm2O2S phases were estimated using the Schröder–Le Chatelier equation. The liquidus lines were calculated using second-degree polynomials and Redlich–Kister model. Coordinates of the ternary eutectic point in the Sm3S4-SmS-Sm2O2S system were calculated using the cutting-plane method and the Scheffé method. The calculated compositions of ternary eutectic points were averaged at one most probable point, in accordance with the data on the samples microstructure. The experimental temperature of the ternary eutectic point coincides with the calculated values within the margin of error. Positions of eutectic valleys and approximate positions of isotherms in the system were established. Thermodynamic parameters of the α-Sm2S3 → γ-Sm2S3 polymorphic transition and the dependence of the Sm2S3-X composition on heat treatment conditions were determined. According to the scanning electron microscopy data, the approximate composition of the crystallized from the melt Sm2S3 sample is Sm2S2.95. The Sm10S14O phase decomposes at 1470 ± 15 °C in the course of a solid-phase reaction. The phase diagram of the Sm2S3-X-Sm2O2S system was revisited. Optical band gaps of Sm10S14O and Sm2O2S phases were determined. The Sm10S14O compound was optically characterized for the first time; its direct and indirect optical bandgaps were found equal to 2.48 and 2.37 eV, respectively. The determined direct and indirect optical bandgaps of Sm2O2S (4.4 eV and 3.95 eV, respectively) agree with the earlier measurements, thus confirming the accuracy of the chosen synthesis procedures. [ABSTRACT FROM AUTHOR]

The phase diagram CaO–Al 2 O 3 –TiO 2 slag system is of great importance for metallurgical processes, such as the utilization of Ti-bearing slag and optimization in Al–Ti alloy steel smelting process. In the present work, the high-temperature phase equilibrium experimental technique was adopted, and the type and composition of equilibrium phases were identified by Electron Probe Micro Analysis (EMPA) and X-ray diffraction (XRD). The iso-thermal section of CaO–Al 2 O 3 –TiO 2 system at 1500 °C in Ar atmosphere was constructed for the first time. There are 10 three-phase fields (Liquid + CaO+3CaO·2TiO 2 , Liquid+3CaO·2TiO 2 +4CaO·3TiO 2 , Liquid + CaO·Al 2 O 3 +4CaO·3TiO 2 , CaO·TiO 2 +CaO·Al 2 O 3 +CaO·2Al 2 O 3 , CaO·2Al 2 O 3 +CaO·TiO 2 +CaO·6Al 2 O 3 , Liquid + Al 2 O 3 +Al 2 O 3 ·TiO 2 , Liquid + CaO·TiO 2 +CaO·6Al 2 O 3 , Liquid + CaO·6Al 2 O 3 +Al 2 O 3 , Liquid + TiO 2 +Al 2 O 3 ·TiO 2 , 4CaO·3TiO 2 +CaO·TiO 2 +CaO·Al 2 O 3), 13 two-phase fields (Liquid + CaO, CaO+3CaO·2TiO 2 , Liquid + Al 2 O 3 , Liquid+3CaO·2TiO 2 , Liquid+4CaO·3TiO 2 , Liquid + TiO 2 , Liquid + CaO·TiO 2 , Liquid + Al 2 O 3 ·TiO 2 , CaO·TiO 2 +CaO·2Al 2 O 3 , Liquid + CaO·6Al 2 O 3 , Liquid + CaO·Al 2 O 3 , 4CaO·3TiO 2 +CaO·TiO 2 , 4CaO·3TiO 2 +3CaO·2TiO 2), 3 single-phase solid solution fields (4CaO·3TiO 2(ss) , 3CaO·2TiO 2(ss) , TiO 2(ss)), and 2 independent single liquid phase fields. Besides, taking the Ti-bearing slag system as an example, the influence of oxygen potential on the activity of (TiO x) was discussed; furthermore, the reasonability of the valence state approximation of element Ti was farther evaluated. [ABSTRACT FROM AUTHOR]

The assembly of Ga alloys with Ni or Ni alloy has been widely developed for various low-temperature applications in recent years. In the constituent Ni-Ga binary system, however, the phase equilibrium with the phase "NiGa5" and its stability has scarcely been investigated. The present study used the diffusion couple technique combined with SEM-EPMA and XRD analysis to examine the phase stability and the homogeneity range of the phase. The results show that "NiGa5" is a stable phase in the binary system with little homogeneity range and suggest that the peritectic reaction L + Ni 3 Ga 7 → NiGa 5 lies between 112.0 and 115.5 °C. This work provides new information for the modification of the Ga-rich low-T region of the Ni-Ga phase diagram. [ABSTRACT FROM AUTHOR]

The phases in uranium-silicide binary system were evaluated in regards to their stabilities, phase boundaries, crystal structures, and phase transitions. The results from this study were used in combination with a well assessed literature to optimize the U-Si phase diagram using the CALPHAD method. A thermodynamic database was developed, which could be used to guide nuclear fuel fabrication, could be incorporated into other nuclear fuel thermodynamic databases, or could be used to generate data required by fuel performance codes to model fuel behavior in normal or off-normal reactor operations. The U3Si2 and U3Si5 phases were modeled using the Compound Energy Formalism model with 3 sublattices to account for the variation in composition. The crystal structure used for the USi phase was the tetragonal with an I4/mmm space. Above 450°C, the U3Si5 phase was modeled. The composition of the USi2 phase was adjusted to USi1.84. The calculated invariant reactions and the enthalpy of formation for the stoichiometric phases were in agreement with experimental data. [ABSTRACT FROM AUTHOR]

The thermodynamic properties of the CaO-Al2O3-VOx slag system are of great significance to the direct alloying of vanadium in the smelting process of vanadium steel. In this paper, the phase equilibrium relationship of the CaO-Al2O3-VOx system under argon atmosphere at 1500 °C was studied with a high-temperature phase equilibrium experiment. Combined with SEM-EDS, XRD, and XPS, the types and compositions of each phase of the equilibrium slag samples and the content of different valence states of the vanadium element were determined. The result shows that under argon atmosphere (p(O2) = 10−3 atm) at 1500 °C, the CaO-Al2O3-VOx slag system contains four three-phase regions, seven two-phase regions, and a single-phase region (glass phase). The phase equilibrium results were plotted in a CaO-Al2O3-V2O5-VO2 spatial phase diagram, and the phase equilibrium results were projected on the CaO-Al2O3-V2O5 and CaO-Al2O3-VO2 pseudo-ternary phase diagrams, respectively. In the end, the rationality of projecting the phase equilibrium results to the pseudo-ternary phase diagram was quantitatively evaluated. [ABSTRACT FROM AUTHOR]

The phase diagram of the Na2O–Al2O3–ZrO2 system was experimentally studied at 1500°C–1650°C by a classical equilibration/quenching method and differential thermal analysis followed by X‐ray diffraction phase analysis and electron probe micro‐analysis. A sealed Pt crucible was utilized to prevent the volatile loss of Na2O during high‐temperature phase equilibrium experiments and the hydration upon quenching. The phase diagram of the Na2O–Al2O3–ZrO2 system was revealed for the first time. Based on the present experimental data and available binary modeling results in literature, the thermodynamic modeling of the ternary system was performed using the Calculation of Phase Diagram method and the phase diagram of the entire the Na2O–Al2O3–ZrO2 system was constructed and the optimized thermodynamic properties for all solids and liquid phase within the ternary system were obtained. [ABSTRACT FROM AUTHOR]

The mixed dibasic acids (DBA) is a by-product during adipic acid (ADA) production by oxidation of cyclohexanol or cyclohexanone, which contains large amount of glutaric acid (GA) with ADA and succinic acid (SA). In this work, we have explored the feasibility of the coupled solution crystallization and melt crystallization for the purification of GA. To obtain fundamental thermodynamic properties for the process design, the gravimetric method was used to measure the solubility of the three dibasic acids in water from 293.15 K to 345.15 K at atmospheric pressure. The results showed that GA was the most soluble component while all solubility increased with increasing temperature. Therefore, it is reasonable to concentrate GA in the liquid phase by cooling crystallization. Similarly, the ternary solid-liquid melt equilibrium phase diagram was constructed based on the experimental data of the three binary subsystems (GA-ADA, GA-SA, ADA-SA). It was found that the concentrated GA after solvent evaporation could be purified by melt crystallization efficiently. Thus a coupled solution crystallization and melt crystallization process was designed. With the operated operating parameters, the purity of GA could reach 99.06% by secondary melt crystallization. Overall, the coupled solution crystallization and melt crystallization method to separate DBA has proven to be effective. [Display omitted] • A novel coupled solution crystallization and melt crystallization method. • Determination of solubility data of three kinds of diacid in water from 293.15 K to 345.15 K. • The solid - liquid equilibrium phase diagrams of three dibasic acids were established by extrapolation. • A process for separating mixed diacid and preparing high purity glutaric acid. [ABSTRACT FROM AUTHOR]

The equilibrium phase relations of the Al 2 O 3 -SiO 2 -CrO x system were experimentally studied at 1600 °C and p O 2 of 10-10-10-11 atm. The high-temperature isothermal equilibration experiments were conducted in a vertical tube furnace, followed by drop quenching and direct phase composition analysis using an Electron Probe X-ray Microanalyzer. The single liquid equilibria, liquid-solid phase equilibria including liquid-corundum, liquid-mullite, and liquid-cristobalite, as well as the three-phase equilibria of liquid-cristobalite-corundum and liquid-corundum-mullite, were observed. The 1600 °C isothermal sections of the quasi-ternary Al 2 O 3 -SiO 2 -CrO x phase diagram at p O 2 of 10-10 and 10-11 atm were constructed. The present experimental results display significant discrepancies with the simulations by MTDATA, FactSage, and Thermo-Calc. [ABSTRACT FROM AUTHOR]

"Phase equilibrium" is one of the most crucial parts in the physical chemistry curriculum. Considering the subject "single component phase diagram analysis" as an example, this paper presents the teaching content, teaching objectives, teaching ideas, teaching design, and complete teaching activities in detail with respect to the "question inquiry" teaching mode. Results show that students learned to find, analyze, and solve problems and achieved better results. [ABSTRACT FROM AUTHOR]

In this study, the phase equilibria of the Nb-V-Hf ternary system at 1300, 1100 and 1000 °C were experimentally investigated by means of back-scattered electron imaging, electron probe microanalysis, and x-ray diffraction. The results show that one ternary Laves compound with a hexagonal C14 structure is found in the isothermal sections that were studied. The bcc phase forms a large continuous solid solution, and no phase separation occurs at 1000 °C as had been claimed in the literature. As the temperature rises from 1000 to 1300 °C, the bcc structure can be observed in the Hf-V side, and the phase region of C15 reduces. [ABSTRACT FROM AUTHOR]

Using the analytical option of the Origin Lab computer program, the analytical dependences of the liquidus temperature on the composition for the PbTe-Bi2Te3, PbTe-Sb2Te3, Bi2Te3-Sb2Te3 boundary systems of the PbTe-Bi2Te3-Sb2Te3 ternary system were determined. Based on these dependencies and thermal analysis data of the ternary system, the analytical model of the temperature-composite dependence of the crystallization surfaces of PbTe, Sb2Te3, Bi2Te3 compounds and PbBi2Te54, PbBi54Te7, PbBi6Te10 phases in the PbTe-Bi2Te3-Sb2Te3 system was determined. The resulting equations made it possible to visualize the phase diagram of the PbTe-Bi2Te3-Sb2Te3 system from the side of the PbTe-Bi2Te3 in 3D coordinates. The analytical model of the phase diagram of the PbTe-Bi2Te3-Sb2Te3 system allowed constructing a threedimensional image of equilibrium phases from different angles, to obtain two-dimensional projections and to tabulate the coordinates of the phase diagram [ABSTRACT FROM AUTHOR]

The equilibrium phase relations of the MgO–SiO2–CrOx system were investigated at 1600°C in air and at pO2 of 10–10 to 10–11 atm using a high‐temperature isothermal equilibration technique followed by rapid quenching and direct phase composition analyses with electron probe X‐ray microanalysis. Two‐phase equilibria (liquid–cristobalite, liquid–spinel, liquid–corundum, and liquid–olivine) and three‐phase equilibria (liquid–cristobalite–spinel, liquid–olivine–spinel, liquid–spinel–corundum, and cristobalite–spinel–corundum) were observed. The 1600°C isothermal sections at various oxygen partial pressures were constructed for the MgO–SiO2–CrOx system based on the experimentally determined liquid and solid compositions. Data from the literature and the predictions by FactSage and MTDATA software were compared with the present experimental results. [ABSTRACT FROM AUTHOR]

Copyright of China Synthetic Fiber Industry is the property of Sinopec Baling Petrochemical Company and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Sichuan Basin of China is a typical underground brine enrichment area. In order to develop and utilize the brine resource, it is necessary to study the phase equilibria and phase diagram of brine systems. In this work, the phase equilibria of the quinary system NaCl + KCl + MgCl2 + SrCl2 + H2O (saturated with NaCl) at 308.2 K of the underground brines in Sichuan Basin are measured experimentally by isothermal dissolution equilibrium method. The phase diagram, water content diagram, and sodium chloride content change diagram of the quinary system with NaCl saturated are also drawn, respectively. The results show that the phase diagram of the quinary system contains three invariant points, seven isothermal solubility curves, and five solid crystal zones at 308.2 K. In the phase diagram, the KCl crystallization area is the largest, followed by SrCl2·6H2O, KCl·MgCl2·6H2O, and SrCl2·2H2O, while MgCl2·6H2O has the smallest crystallization area. Magnesium chloride in the quinary system has the largest solubility and has strong salting‐out effect on other salts. Furthermore, the unreported mixed ion interaction parameters θMg, Sr and ΨMg, Sr, Cl of Pitzer model are fitted, respectively. Consequently, the solubilities of the quinary system NaCl + KCl + MgCl2 + SrCl2 + H2O at 308.2 K are predicted using the Pitzer model, and the calculated phase diagram at 308.2 K is also plotted in detail. The predicted solubilities of the quinary system were in good agreement with the experimental solubilities. Finally, the study on the phase equilibrium of the quinary system can provide phase equilibrium data for the development and utilization of liquid mineral resources. [ABSTRACT FROM AUTHOR]

An experimental study of the phase equilibria of the Ho-rich part of the Ho-Ir-O ternary system at 1073 K by means of x-ray diffraction, differential scanning calorimetry, and scanning electron microscopy has been carried out. Ho-hcp and four binary compounds, namely Ho3Ir, Ho5Ir2, Ho5Ir3, and Ho2O3, were identified in the Ho-Ir-O model alloys after long-term annealing (350–1220 h). No solubility of iridium in Ho2O3 oxide and Ho-hcp was observed. No ternary phase was found. Based on the experimental results, an isothermal section of the Ho-rich part of the Ho-Ir-O system at 1073 K was constructed. In addition, the microstructure of as-cast alloys was studied. An irregular eutectic consisting of faceted Ho-phase in Ho3Ir phase was observed in the alloys with Ho-hcp + Ho3Ir + Ho2O3 phase composition, and the temperature of the eutectic reaction Ho-hcp + Ho3Ir ↔ liquid was determined. [ABSTRACT FROM AUTHOR]

The phase relationships of the Ni-Al-Cr-Y quaternary system can provide theoretical guidance for the design of MCrAlY (M = Ni and/or Co, Fe) overlay coatings on the surface of superalloys. The 900 °C isothermal section of the Ni-Al-Cr-Y quaternary system with Ni fixed at 55 at.% and the Ni-Al-Y ternary system were studied experimentally by using equilibrated alloys, with x-ray diffraction and scanning electron microscopy with energy dispersive spectroscopy. Thirty three-phase regions were confirmed, and six three-phase regions were determined in the isothermal section of the Y-poor side in Ni-Al-Y ternary system at 900 °C. Aluminium could replace Ni in the line compounds Ni5Y, Ni3Y and Ni2Y; similarly, Ni could replace Al in the line compounds Al2Y, AlY and Al2Y3. The experimental results showed that there are twelve ternary compounds stable at 900 °C, and the τ13-Ni6Al16Y3 phase and τ14-NiAl3Y2.25 phase are the new ternary compounds found in this work with composition ranges from about 23.5-24.9 at.% Ni, 63.1-64.8 at.% Al, 11.2-12.1 at.% Y and 16.3-17.0 at.% Ni, 47.2-48.2 at.% Al, 35.5-36.8 at.% Y, respectively. In the isothermal section of the Ni-Al-Cr-Y quaternary system at 900 °C with 55 at.% Ni, six four-phase regions were experimentally determined, and one four-phase region was inferred. The results indicated that (Cr) could equilibrate with all phases in the quaternary system. In the present work, no new quaternary compounds were found. [ABSTRACT FROM AUTHOR]

A high-temperature and high-pressure optical cell VLE apparatus has been applied to measure phase equilibrium properties of n-tetradecane in the supercritical binary solvent (0.367propane + 0.633 n-butane mass fraction) at temperatures of 413.15 K, 433.15 K, and 453.15 K between of pressures (0.9 and 6.6) MPa. The combined expanded uncertainty of the temperature, pressure, and concentration measurements at 0.95 confidence level with a coverage factor of k = 2 is estimated to be 0.15 K, 0.0022, and 0.035, respectively. The critical parameters (TC, PC, w C ) were determined based on the measured isothermal phase equilibrium data of the ternary system n-tetradecane + propane/n-butane. It is shown that the critical temperature and pressure of the n-tetradecane + propane/n-butane system increases with concentration of n-tetradecane increases. [ABSTRACT FROM AUTHOR]

The phase equilibrium in an acetonitrile + water + cyclohexene + chloroform system was studied at 101.3 kPa. A prediction regarding the internal structure of the composition tetrahedron (presence/absence of one/two internal singular points) was made using thermodynamic modeling in AspenPlus V.10.0. The existence of two internal quaternary azeotropes (of node type with a minimum boiling point and of saddle type) was confirmed as a result of a full-scale experiment. Thermodynamic-topological analysis of the structure of phase equilibrium diagrams was carried out to confirm the correctness of the diagram construction. [ABSTRACT FROM AUTHOR]

The aim this work was the reinvestigation of phase equilibria in Bi-Te system. The as-cast and long-time equilibrated alloys of Bi-Te binary system were analysed by scanning electron microscopy, X-ray diffraction (XRD) and differential thermal analysis (DTA) methods. The primary solidified phases were identified for as-cast samples. The existence of the four intermetallic phases: Bi2Te3, BiTe, Bi2Te, Bi7Te3 was confirmed. Three of them melt incongruently in peritectic reactions. The model parameters of all phases in this system were assessed by optimization using available data by Calphad method. The stabilisation of these phases in other ternary systems was discussed taking into consideration its future application in thermodynamic description of Ag-Bi-Te ternary system. [ABSTRACT FROM AUTHOR]

The phase equilibria of the Cu2S-SiS2-GeS2 system have been studied in the Cu2S-Cu8SiS6-Cu8GeS6 composition area. Based on data obtained from differential thermal analysis, powder x-ray diffraction, and SEM-EDS techniques, the T-x diagram of the Cu8SiS6-Cu8GeS6 boundary system and two internal polythermal sections, as well as the isothermal section at 300 K of the phase diagram and the liquidus surface of the Cu2S-Cu8SiS6-Cu8GeS6 system were constructed. The areas of primary crystallization and homogeneity of phases, the nature, and temperatures of invariant and monovariant equilibria were determined. Continuous solid solutions based on both crystalline modifications of the starting compounds of the Cu8SiS6-Cu8GeS6 boundary system, have been revealed, which are of interest as environmentally friendly functional materials. The temperatures and enthalpies of phase transitions of Cu8SiS6 and Cu8GeS6 compounds, and Cu8Si(1−X)GeXS6 solid solutions were determined using differential scanning calorimetry. The entropies of phase transitions for end-member compounds were also calculated. It is shown that the heats and entropies of phase transitions of these phases are anomalously large in comparison with the thermodynamic functions of ordinary polymorphic transitions. Apparently, this is due to a significant increase in the degree of disorder in the cationic sublattice upon transition to the high-temperature ion-conducting phase. It has also been established that the heats of phase transitions of solid solutions are practically equal to the sum of the corresponding functions of the end-member compounds. [ABSTRACT FROM AUTHOR]

Magnetic contributions have the potential to significantly influence predicted phase stability within alloy and mineral mixing phase diagrams, yet have been historically challenging to incorporate due to a significant increase to phase space sampling. In this work, we employ a computational protocol that includes spin orientation as an additional configurational component within multi-component cluster expansions between magnetic and non-magnetic metal oxide alloys [calculated using density functional theory (DFT) and the generalized gradient approximation]. This approach was used to determine the efect of magnetic contributions to corundum-eskolaite and corundum-hematite phase equilibria from first principles. Two-component cluster expansions of the magnetic components of eskolaite and hematite were first performed showing the ability of this method to properly calculate their respective magnetic properties. Two-component cluster expansions were then performed for non-magnetic Al(III) and ferromagnetic Cr(III) and Fe(III), and phase diagrams were calculated for later comparison. Finally, a non-magnetic Al(III) and "up" and "down" magnetic configurations for anti-ferromagnetic Cr(III) and Fe(III) were performed. Magnetic contributions to the calculated phase diagram for the corundumeskolaite system were shown to be inconsequential but are vital for accurate determination of the corundum-hematite solvus. [ABSTRACT FROM AUTHOR]

Differential scanning calorimetry technique was used to investigate phase equilibria in the YbCl2–MCl (M = Li, Na) binary systems. The YbCl2–LiCl system exhibits an eutectic located at YbCl2 mole fraction x = 0.415 (733 K) and a LiYb2Cl5 stoichiometric compound that is formed at 711 K and melts incongruently at 742 K. The YbCl2–NaCl system exhibits an eutectic located at YbCl2 mole fraction x = 0.559 (764 K). In both systems the formation of solid solutions in the MCl-rich side (M = Li, Na) has been found. The molar enthalpies of mixing (ΔHMIX) in the liquid YbCl2–MCl (M = Na, K) mixtures have been measured at 1085 K with a Calvet-type high temperature microcalorimeter in the entire range of composition. A negative value of mixing enthalpy was observed for all melts. The minimum value was of approximately: − 2.5, and − 7.5 kJ mol−1, for systems with NaCl and KCl, respectively. All the experimental results along with the available literature data were used to optimize the thermodynamic properties of the investigated systems using the CALPHAD method. [ABSTRACT FROM AUTHOR]