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The lack of thermodynamic data on vanadium slag, the main raw material for vanadium extraction, limits the efficient extraction of vanadium from vanadium slag. According to the composition and smelting process of industrial vanadium slag, this study firstly investigated the phase equilibria of the "FeO"–SiO2–CaO–16 wt pctV2O3 system at 1673 K and 1473 K under oxygen partial pressure of 10−10 atm via XRD, SEM and EPMA, based on which the phase diagrams of that at 1673 K and 1473 K were constructed. The results showed that the vanadium-enriched phases mainly consisted of V2O3, Fe2VO4, and Ca3[Fe,V]2(SiO4)3, where Ca3[Fe,V]2(SiO4)3 was generated due to the replacement of a large amount of Fe3+ by V3+ in Ca3Fe2(SiO4)3. On this basis, the phase relations of the "FeO"–SiO2–CaO–16 wt pctV2O3 system were further discussed. It was found that the decrease in temperature promoted the crystallization of Fe2VO4 and Ca3[Fe,V]2(SiO4)3, but had an inhibitory effect on the crystallization of V2O3. And Fe2VO4 was transformed to V2O3 or Ca3[Fe,V]2(SiO4)3 by decreasing Fe/Si (Mass fraction of "FeO" and SiO2). This study supplements the thermodynamic data for vanadium slag and provides a theoretical basis for the recovery of vanadium from vanadium slag. [ABSTRACT FROM AUTHOR]

The very low C content in interstitial-free (IF) steel is achieved through vacuum degassing and by adding Ti to Al-deoxidized molten steel during the steelmaking process. However, this low C content can lead to reoxidation, which, in turn, generates various oxide inclusions. Despite its significance, a comprehensive understanding of the evolution of these oxide inclusions has been hindered by the scarcity of fundamental information, such as phase equilibria in the relevant system. In this study, the thermodynamics and phase equilibria of the Fe-Al-Ti-O system, along with the evolution of oxide inclusions in the molten steel, were analyzed using various analytical techniques: CALculation of PHAse Diagrams (CALPHAD), scanning electron microscopy, energy dispersive spectroscopy, electron backscatter diffraction, and confocal scanning laser microscopy. High-temperature monitoring of oxide inclusion evolution through in-situ CSLM, SEM, and EBSD revealed that the primary constituents of the major oxide inclusions were alumina (corundum). Notably, (Ti, Al, Fe) 3 O 5 , exhibiting a pseudobrookite structure, was identified at higher O potentials, indicative of the reoxidation phenomena in molten steel. To advance the understanding of the stability of oxide inclusions in the molten steel at equilibrium, a self-consistent CALPHAD model was developed. This model provided insights into the stability and evolution of oxide inclusions within this system for the first time. It was demonstrated that the transition from alumina to (Ti, Al, Fe) 3 O 5 is influenced not only by the Al and Ti concentrations in the molten steel but also by the O content (or potential) within the system. The presence of (Ti, Al, Fe) 3 O 5 as an O carrier in molten steel adversely affects the steel's cleanliness. [ABSTRACT FROM AUTHOR]

The phase equilibria and division of the Ag2S–GaS–Ga2S3–FeS2–FeS–Ag2S region (A) of the Ag–Fe–Ga–S system below 600 K were established by the modified EMF method. The electrochemical cells (ECs) of the following structure were assembled: (−)C||Ag||SE||R(Ag+)||PE||C(+), where C is the graphite; Ag is the left electrode; SE is the solid-state electrolyte; PE is the right electrode; R(Ag+) is the region of Ag+ diffusion in the PE. Initially assembled PEs are a nonequilibrium phase mixture of binary sulfides with the ratios of simple substances covering all composition space of (A). The catalyst for the reactions in R(Ag+) were Ag+ ions acting as small nucleation centers of equilibrium mixtures of compounds. The division of (A) was realized with the participation of the binary as well as more complex compounds AgGaS2, Ag9GaS6, AgFeS2, Ag2FeS2, Ag2FeGa20S32, Ag2FeGa2S5, and Ag18Fe9Ga2S21. The spatial position of the three- and four-phase regions relative to the Ag point was employed to establish the overall potential-forming reactions for synthesizing quaternary phases in the PEs of ECs. The temperature dependencies of the electromotive force of ECs were used to calculate the values of the standard thermodynamic functions of the quaternary compounds. [ABSTRACT FROM AUTHOR]

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Vapor–liquid phase equilibrium (VLE) plays a crucial role in chemical process design, process equipment control, and experimental process simulation. However, experimental acquisition of VLE data is a challenging and complex task. As an alternative to experimentation, VLE data prediction offers great convenience and utility. In this article, an artificial intelligence network is proposed to predict the temperature and the vapor phase composition of binary mixtures. We constructed a graph neural network (GNN) and designed an uncertainty‐aware learning and inference mechanism (UALF) in the prediction process. The model was tested on both a self‐constructed dataset and a publicly available dataset. The results demonstrate that the proposed method effectively reveals the phase equilibrium properties of the target data. This work presents a novel approach for predicting vapor–liquid phase equilibrium in binary systems and proposes innovative ideas for investigating phase equilibrium mechanisms and principles. [ABSTRACT FROM AUTHOR]

Lead and silver thiogallates are notable for their practical applications in nonlinear optical devices, detectors, solar cells, photodiodes, and phosphors. This study aims to develop materials with multifunctional properties and investigate the AgGaS2--PbGa2S4 system. The initial sulfides, AgGaS2 and PbGa2S4, were synthesized from high-purity elements sealed in evacuated quartz ampoules (0.133 Pa). Complex alloys of the AgGaS2--PbGa2S4 system were prepared at 1200--1350 K. Polycrystalline samples were annealed at 850 K for 270 hours. Phase equilibria in the AgGaS2--PbGa2S4 system were analyzed using a combination of physicochemical methods, including differential thermal analysis, powder X-ray diffraction, microstructural analysis, microhardness, and density measurements, and the phase diagram was constructed. The system was identified as a quasi-binary section of the quasi-ternary Ag2S--Ga2S3--PbS system, belonging to the eutectic type. The eutectic point was determined at 1100 K and 55 mol.% PbGa2S4. Solid solution regions were identified based on the primary components. At room temperature, the AgGaS2 solid solution region extends to 10 mol.% PbGa2S4, while the PbGa2S4 solid solution region extends to 18 mol.% AgGaS2. At the eutectic temperature, these solubilities increase to 20 and 25 mol.%, respectively. AgGaS2-based solid solutions crystallize in chalcopyrite-type structures, while PbGa2S4-based solid solutions adopt orthorhombic structures. [ABSTRACT FROM AUTHOR]

Accurately predicting the phase behavior and properties of reservoir fluid plays an essential role in the simulation of petroleum recovery processes. Similar to the inaccurate liquid-density prediction issue in the isobaric-isothermal (PT) phase equilibrium calculations, an inaccurate pressure prediction issue can also be observed in isothermal-isochoric (VT) phase equilibrium calculations which involves a liquid phase. In this work, a practical methodology is proposed to incorporate a volume-translated equation of state in VT phase equilibrium calculations for more accurate pressure predictions. For this purpose, we adopt the state-of-art volume translation model recently proposed by Abudour et al. (Fluid Phase Equilib 349:37–55 2012, Fluid Phase Equilib 349:37–55, 2013). Single liquid phase calculations for 18 compounds and two hydrocarbon mixtures are conducted to demonstrate the soundness of the proposed methodology and evaluate the accuracy of pressure predictions. The calculated pressures by VT calculations with volume translated PR-EOS are compared to the actual pressures. The calculation results demonstrate that, by incorporating Abudour et al. (2012, 2013) volume translated PR-EOS models into the VT-based phase equilibrium calculation algorithm, the accuracy of pressure prediction in the single liquid phase region for both pure substances and mixtures can be significantly improved. Lastly, we apply the proposed algorithm to the two-phase VT phase equilibrium calculations for a ten-component oil sample MY10 which contains only normal alkanes. We numerically correct the pressure by applying the Abudour et al. VTPR-EOS to both the liquid phase and vapor phase. The pressures calculated by different phases become different. The pressures predicted based on the liquid phase are shifted downwards significantly, which leads to more accurate pressure predictions. To our knowledge, this issue is rarely investigated to incorporate the volume translation concept in VT phase equilibrium calculations. [ABSTRACT FROM AUTHOR]

CO2 flooding plays a crucial role in enhancing oil recovery and achieving carbon reduction targets, particularly in unconventional reservoirs with complex pore structures. The phase behavior of CO2 and hydrocarbons at different scales significantly affects oil recovery efficiency, yet its underlying mechanisms remain insufficiently understood. This study improves existing thermodynamic models by introducing Helmholtz free energy as a convergence criterion and incorporating adsorption effects in micro- and nano-scale pores. This study refines existing thermodynamic models by incorporating Helmholtz free energy as a convergence criterion, offering a more accurate representation of confined phase behavior. Unlike conventional Gibbs free energy-based models, this approach effectively accounts for confinement-induced deviations in phase equilibrium, ensuring improved predictive accuracy for nanoscale reservoirs. Additionally, adsorption effects in micro- and nano-scale pores are explicitly integrated to enhance model reliability. A multi-scale thermodynamic model for CO2-hydrocarbon systems is developed and validated through physical simulations. Key findings indicate that as the scale decreases from bulk to 10 nm, the bubble point pressure shows a deviation of 5% to 23%, while the density of confined fluids increases by approximately 2%. The results also reveal that smaller pores restrict gas expansion, leading to an enhanced CO2 solubility effect and stronger phase mixing behavior. Through phase diagram analysis, density expansion, multi-stage contact, and differential separation simulations, we further clarify how confinement influences CO2 injection efficiency. These findings provide new insights into phase behavior changes in confined porous media, improving the accuracy of CO2 flooding predictions. The proposed model offers a more precise framework for evaluating phase transitions in unconventional reservoirs, aiding in the optimization of CO2-based enhanced oil recovery strategies. [ABSTRACT FROM AUTHOR]

This study investigated the effects of laser energy density at different scanning speeds on the microstructure evolution, phase equilibrium, mechanical properties, and fracture modes of welds in dissimilar steel welded joints (Q345D and 20Mn2). The connection of dissimilar steel welded joints is achieved by using a laser synchronous powder feeding method. The microstructure and phase evolution of the joint were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Mechanical property testing was performed on the joint via a micro-Vickers hardness tester and an electronic testing machine, and the fracture surface morphology was observed via a scanning electron microscope. The results show that when the laser energy density is 1125 J/mm2, the fine cellular crystals, columnar crystals, and equiaxed crystal structures of the joint are more uniformly distributed. As the laser energy density increased, the transition of the Q345D side structure from cellular to columnar crystals and the transition of the 20Mn2 side structure from cellular to equiaxed crystals became more pronounced. Mechanical property testing revealed that an increase in the laser energy density can significantly improve the microhardness and tensile strength of a joint. However, a large amount of the Fe matrix from the 20Mn2 side permeates into the coating, making the mechanical properties of the dilution zone lower than those of the crystallization zone, and making it more prone to fracture on this side. The fracture analysis results show that the fracture mode has strong ductility, and the fracture mode is judged to be ductile fracture. [ABSTRACT FROM AUTHOR]

Re di Castello is the southernmost unit of the composite Adamello batholith (central Alps, Italy). It was emplaced between 43 and 40 Ma, yet its depth of emplacement is not well constrained. We have studied the contact metamorphism of pelitic country rocks in two localities: the upper Caffaro Valley and the Borzago Valley in the southern and the northern sub‐units of the Re di Castello, respectively. In the Caffaro Valley, the country rocks comprise the Triassic sedimentary Lozio Shale, a carbon‐rich slate–siltstone, which was intruded by quartz‐dioritic magma. Near the contact, the hornfelses display the mineralogical assemblage Kfs‐Crd‐Bt‐Ms‐Pl‐Qz‐Gr, with rare fibrolitic sillimanite in a single sample. Andalusite was never observed throughout the aureole at this locality. In the Borzago Valley, contact metamorphism developed on schists of the pre‐Permian basement with a Variscan, regional metamorphic overprint. The sequence of contact metamorphic mineral assemblages progresses from And‐Bt‐bearing parageneses to the Sil‐Crd‐Bt‐Kfs‐Ms‐Pl‐Qz that characterizes peak conditions, at which incipient melting is also observed. K‐feldspar forms slightly upgrade the first appearance of sillimanite. For samples at both localities, thermodynamic modelling in the NCKFMASHT system failed at predicting a stability field for the sequences of mineral assemblages developed during contact metamorphism. Also the Ti‐in biotite thermometer did not constrain temperatures adequately. The P–T conditions at the thermal peak were thus evaluated by an alternative bathograd‐like approach, considering phase relationships in the simplified NKASH‐C system. To form sillimanite only as product of the incomplete Ms‐Qz breakdown—divariant for the presence of Na in Ms and Kfs and shifted to lower temperature due to the presence of graphite (in the Lozio Shale)—an isobaric path typical of contact metamophism must have crossed above the Msss‐Qz‐Kfsss‐Sil‐And‐fluid invariant point. This constrains an emplacement pressure >3.3 kbar in the Caffaro Valley, and >3.2 kbar in the Borzago Valley. Concerning temperature, the same univariant point also constrains the minimum temperature in the Caffaro Valley as >615°C–620°C, consistent with results of RSCM thermometry on graphite from the Lozio Shale. The evidence of incipient melting in some samples from the Borzago Valley indicates higher temperatures, probably approaching 670°C, near the contact to the intrusion. Assuming an average crust density of 2.7 g cm−3, the estimated pressures correspond to a minimum paleo‐depth of emplacement of about 12 km. These depths are somewhat greater than normally considered and should be regarded as revised constraints on models of the emplacement dynamics of the Adamello batholith and on paleogeographic reconstructions of this part of the Southalpine domain. [ABSTRACT FROM AUTHOR]

Eclogite‐facies rocks provide important constraints on the behaviour of convergent plate boundaries and the geometries of tectonic reconstructions due to the high to ultrahigh pressure conditions at which they form. Many eclogite occurrences are documented near the suture zone of active collisional settings where they are interpreted to mark the approximate location of former ocean basin subduction. Such observations influence tectonic interpretations for older eclogites within more deeply eroded and/or less well‐exposed terranes. The eclogitic Glenelg inlier in northwest Scotland is one such example, with c. 1 Ga eclogites having previously been interpreted as marking the trace of a Grenville‐aged collisional suture zone that defines a third 'arm' to the Grenville orogen alongside well‐defined sutures in North America and Scandinavia. Here we use a combination of geochronology, phase equilibrium modelling and accessory‐phase thermometry to show that the eclogite‐facies assemblages were produced at ∼$$ \sim $$18–19 kbar and 700°C–750°C from c. 1.1 to 1.0 Ga. Accounting for the foreland basin setting of equivalent‐aged sedimentary rocks in the region and demonstrating the thermal viability of this setting, we show that eclogite formation occurred in deforming foreland crust adjacent to the Grenville orogen, in a setting broadly analogous to fault‐bounded basement uplifts in the forelands of active deformation belts, such as the Himalayas and Andes. Our results demonstrate that eclogite‐facies rocks can form in a greater range of tectonic settings than are sometimes considered, with implications for tectonic reconstructions of collisional zones. In this instance, our results remove the need for a third 'arm' of the Grenville orogen by placing Glenelg in a foreland setting, reconciling the absence of plentiful Grenville‐aged metamorphic rocks in northwest Scotland, the sedimentological record and paleomagnetic data in the wider region. [ABSTRACT FROM AUTHOR]

Phase equilibrium modelling is a powerful method for obtaining pressure–temperature (P–T) estimates in metapelites; however, the advantages, disadvantages, and limitations of applying this technique to greenschist‐facies pelites have received little attention. This study uses two greenschist‐facies metapelites from the Nappe Zone in Sardinia (Italy) to examine differences between currently available thermobarometric techniques. First, this work compares P–T estimates from chlorite–K‐white mica–quartz–water and K‐white mica–quartz–water multiequilibrium approaches, the latter integrated with previously published Tmax results from Raman spectroscopy on carbonaceous material. Consistent P–T conditions are retrieved from these methods for both samples, with P–T estimates suggesting a difference in peak metamorphic conditions between the Internal and External Nappe Zones of Sardinia (peak P–T conditions of 0.6–0.8 GPa, 420°C–450°C and 0.4–0.5 GPa, 370°C–400°C for the Internal and External Nappes, respectively). Second, phase equilibrium modelling was used to assess the ability of six different sets of solution models, alongside their associated thermodynamic datasets, to constrain P–T conditions in the same samples, which are characterized by high‐variance mineral assemblages. Significant differences were found between the six thermodynamic databases, and important discrepancies were recognized between the observed and predicted mineral assemblages and compositions (e.g., Si in K‐white mica). In only one sample, three databases were able to predict the observed natural assemblage. The compositional isopleths for K‐white mica, from the same databases, do not intersect, offering no assistance in constraining P–T conditions. However, one database predicted chlorite's natural composition, yielding a P–T estimate consistent with multiequilibrium methods: ~0.9 GPa, ~350°C–400°C for the Internal Nappe Zone and ~0.5 GPa, ~300°C–350°C for the External Nappe Zone. Although P–T conditions constrained using calculated isopleths from greenschist‐facies metapelites and databases optimized for modelling low‐grade to medium‐grade pelitic systems may be reliable, they should be applied cautiously and compared with estimates from inverse and independent approaches. [ABSTRACT FROM AUTHOR]

Petrochronological investigations of granulite‐facies metapelitic rocks from the eastern contact of the Closepet granite in the Central Dharwar Craton (CDC), southern India, provide new pressure–temperature–age (P–T–t) constraints on two seemingly discrete Archean metamorphic events during the Neoarchean and late Paleoarchean eras. Phase equilibrium modelling and conventional thermobarometry coupled with in situ monazite and garnet geochronology constrain Neoarchean (ultrahigh‐temperature; UHT) metamorphic peak conditions to ~930 °C and ~6.7 kbar at c. 2.63 Ga, then cooling and limited decompression to ~5.7 kbar at ≤810 °C. Monazite inclusions in garnet least affected by Neoarchean recrystallisation have distinct positive Eu anomalies and yield ages of c. 3.2 Ga, whereas garnet cores interpreted to have grown at the same time have slightly younger apparent ages of c. 3.1 Ga. We interpret this age mismatch to be the result of extensive resorption of garnet during Neoarchean UHT metamorphism, which led to widespread modification of the initial Lu–Hf systematics in garnet to produce younger apparent ages. The effect of retention and inward intracrystalline diffusion of Lu on the isotopic composition of garnet is most pronounced close to the resorbed grain margins and decreases towards the core, as reflected by progressively younger apparent single‐spot garnet dates from core to rim. Despite extensive overprinting of the sample at c. 2.63 Ga, the trace element composition of Paleoarchean monazite indicates growth in equilibrium with garnet but in the absence of feldspar, which is predicted to occur over a broad stability range at P ≥ 8 kbar and T ≤ 700 °C. Such P–T conditions are uncommon in the metamorphic rock record prior to the Neoarchean, but are typical of Barrovian‐type metamorphism, which is considered to be an expression of accretionary‐to‐collisional orogenesis. Rocks of similar age and metamorphic grade have been reported from the core of the Western Dharwar Craton (WDC) and may reflect regional subduction at the margins of the CDC and WDC since the late Paleoarchean. Neoarchean UHT metamorphism in the Dharwar Craton is coeval with a cluster of other UHT occurrences at 2.7–2.6 Ga, indicating the existence of globally elevated thermal gradients at that time. [ABSTRACT FROM AUTHOR]

The dynamic recrystallization (DRX) behavior of SA508‐III steel, a critical material for reactor pressure vessels (RPVs) normally treated by hot forging, is thoroughly examined in this article. In the investigation, elevated temperatures and the coarsening of metallic phases and carbides are revealed to contribute to the degradation of the steel's strength–toughness relationship. Utilizing computational thermodynamics, the stability of secondary phases, including carbides and brittle inclusions, is simulated to enable precise phase equilibrium calculations and accurate prediction of key mechanical properties such as yield strength, tensile strength, and hardness. These simulations facilitated targeted modifications to the alloy composition to enhance the steel's strength and hardenability under high‐temperature, high‐pressure conditions. In this study, alloy composition and processing parameters within the CALculation of PHAse Diagram framework, utilizing the ThermoCalc and JMatPro software packages, are optimized. In the microstructural investigations conducted under various isothermal deformation conditions (1173–1473 K) and strain rates (0.001–1 s−1), it is demonstrated that DRX mechanisms led to varied grain size developments, with a critical strain rate identified at 0.01 s−1 during high‐temperature deformations. In these findings, significant insights are provided into optimizing the mechanical performance of SA508‐III steel for RPV applications. [ABSTRACT FROM AUTHOR]

Lawsonite eclogites represent cold subduction in the rock record, and new localities provide rare natural field laboratories to investigate deep deformation processes. We present a new lawsonite eclogite locality near Faro, Yukon Territory, Canada, the first reported lawsonite eclogite locality of the Yukon-Tanana Terrane. The discovery indicates that mid- to Late Permian subduction in the Yukon-Tanana Terrane subducted cold material in an oceanic subduction zone, in contrast to most previous models. We define a pressure-temperature-deformation (P-T-d) pathway for the lawsonite eclogites using a combination of microstructures, mineral compositional mapping, crystal orientation mapping, and phase equilibrium modeling. Metamorphism in the Faro eclogites followed a clockwise pathway through the lawsonite eclogite facies, reaching peak pressures of 22-24 MPa at 525-550 °C. Rocks then exhumed to 14.5-16 MPa during heating to 630-655 °C. Crystallographic preferred orientations (CPOs) in omphacite developed dominantly by dissolution-precipitation creep and oriented grain growth concurrently with CPOs developed in glaucophane by a combination of dislocation- and dissolution-precipitation creep with oriented grain growth. We link this fabric and CPO development in omphacite and amphibole to lawsonite dehydration, slab decoupling, and initiation of exhumation of the eclogites, providing evidence that lawsonite dehydration plays a significant role in changes in subduction zone rheology. [ABSTRACT FROM AUTHOR]

The Archean basement rocks in the Eastern Block of the North China Craton have undergone extensive granulite-facies metamorphism during the late Neoarchean to Paleoproterozoic. However, the geodynamic process and associated tectonic regime of this area remain poorly understood. The Qingyuan area of Northern Liaoning, located in the nucleus of the Eastern Block, plays a crucial role in unraveling the tectonothermal evolution by reconstructing its metamorphic history. Previous studies have mainly focused on the northern part of the area, while the tectonothermal evolution of the southern part remains unknown. In this study, we utilized petrography, phase equilibria modeling, and geochronology to constrain the pressure-temperature-time (P-T-t) paths of representative metapelite and metabasite samples of the area. Our results indicate that both samples have recorded anticlockwise P-T-t paths. The peak condition for the metapelitic rock sample 22QY02-9 is 10.0-11.2 kbar/800-815 °C. U-Pb zircon and monazite dating results indicate a postpeak metamorphic age of ca. 2470-2450 Ma. Metamafic rock sample 22QY04-3 reaches the ultrahigh temperature peak metamorphic condition of 11.5-12.5 kbar/920-950 °C, which is consistent with the results obtained from the ternary-feldspar thermometry calculations. U-Pb zircon dating reveals a cooling age of metamorphism at ca. 2487 Ma. By combining the data from this study with previous research, a sagduction model, operating under a non-plate tectonics regime, appears to be the most promising explanation for the most prevalent geological phenomena in the Neoarchean North China Craton. [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]

Permian–Triassic eclogites exposed on the Tibetan Plateau have traditionally been attributed to Paleo-Tethys oceanic subduction. Here we report new data that indicate a continental-subduction origin of the Pianshishan eclogites along the Longmuco-Shuanghu Paleo-Tethys suture in northern Tibet. Phase equilibrium modeling and zircon U-Pb dating constrain eclogite-facies metamorphism of ∼2.1 GPa/530 °C to have occurred ca. 235 Ma. Xenocrysts of ca. 1850 Ma metamorphic zircons and crustal trace element signatures reveal a continental protolith for the Pianshishan eclogites, demonstrating deep subduction of continental passive margins during the early Late Triassic. The Qianmai eclogites along the Changning-Menglian suture in Southwest China have the same petrogenesis, indicating that these two coeval eclogites resulted from continental subduction that extended over 2500 km along the Paleo-Tethys suture. This collision not only marks the end of the Paleo-Tethys Wilson cycle but also could have formed a high-elevation range, comparable in length to the Himalaya, that amplified Tethyan megamonsoons during the Late Triassic Carnian Pluvial Episode. [ABSTRACT FROM AUTHOR]

We investigate equilibrium magnetic phases of spin s = 3/2 system with SU(4) symmetry of exchange interaction. The classification equations for order parameters that violate SU(4) symmetry have been derived and exact solutions of these equations for subgroups SO(3), SO(3) × U(1), SO(3) × SO(3), SU(3), SU(3) × U(1), SO(4), SO(4) × U(1), SO(5) symmetry have been obtained. [ABSTRACT FROM AUTHOR]

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]

Tungsten mineralization in the Bodó mineral district (9 Mt with an average grade of 2% WO3) is in a sequence of metasomatized marbles and W-(Mo)-skarn lenses in the Seridó Belt, northern Borborema Province. The marble lenses have variable amounts of diopside, grossular, scapolite, phlogopite, and tremolite. The skarn lenses are mainly composed of massive grossular, diopside, vesuvianite, epidote, and quartz. A spatially related granite yielded a SHRIMP U‒Pb zircon date of 536.6 ± 3.4 Ma and a 40Ar/39Ar biotite date of 490.65 ± 0.67 Ma, whereas a nearby pegmatite yielded a 40Ar/39Ar muscovite date of 501.63 ± 0.59 Ma. Literature data for molybdenite in the skarn mineralization yielded a Re‒Os date of 510 ± 2 Ma, which is coeval with U‒Pb dates of columbite-tantalite from other regional pegmatites (515–509 Ma). Therefore, it is likely that pegmatite magmatism acted as the source of fluid and heat for the mineralization. The C–O stable isotope data for marbles and skarns are consistent with interaction of magmatic fluid and host marble at variable XCO2 conditions. T-XCO2 pseudosections define peak conditions of metamorphism/metasomatism at 650–600 °C over a wide range of XCO2 (between 0.4 and 0.8), whereas the retrograde stage started at ~ 550 °C. Late garnet crystallization at low XCO2 (< 0.2) indicates high H2O influx, while scapolite crystallization required high XCO2 (~ 0.8). Together with the interpretation of textural relationships, these observations indicate that skarn and marble formation occurred under open-system conditions with fluctuating XCO2 fluid composition as a consequence of magmatic fluid infiltration. [ABSTRACT FROM AUTHOR]

W-Mo-V high-speed steel (HSS) is a high-alloy high-carbon steel with a high content of carbon, tungsten, chromium, molybdenum, and vanadium components. This type of high-speed steel has excellent red hardness, wear resistance, and corrosion resistance. In this study, the alloying element ratios were adjusted based on commercial HSS powders. The resulting chemical composition (wt.%) is C 1.9%, W 5.5%, Mo 5.0%, V 5.5%, Cr 4.5%, Si 0.7%, Mn 0.55%, Nb 0.5%, B 0.2%, N 0.06%, and the rest is Fe. This design is distinguished by the inclusion of a high content of molybdenum, vanadium, and trace boron in high-speed steel. When compared to traditional tungsten-based high-speed steel rolls, the addition of these three types of elements effectively improves the wear resistance and red hardness of high-speed steel, thereby increasing the service life of high-speed steel mill-roll covers. JMatPro (version 7.0) simulation software was used to create the composition of W-Mo-V HSS. The phase composition diagrams at various temperatures were examined, as well as the contents of distinct phases within the organization at various temperatures. The influence of austenite content on the martensitic transformation temperature at different temperatures was estimated. The heat treatment parameters for W-Mo-V HSS were optimized. By studying the phase equilibrium of W-Mo-V high-speed steel at different temperatures and drawing CCT diagrams, the starting temperature for the transformation of pearlite to austenite (Ac1 = 796.91 °C) and the ending temperature for the complete dissolution of secondary carbides into austenite (Accm = 819.49 °C) during heating was determined. The changes in carbide content and grain size of W-Mo-V high-speed steel at different tempering temperatures were calculated using JMatPro software. Combined with analysis of Ac1 and Accm temperature points, it was found that the optimal annealing temperatures were 817–827 °C, quenching temperatures were 1150–1160 °C, and tempering temperatures were 550–610 °C. The scanning electron microscopy (SEM) examination of the samples obtained with the aforementioned heat treatment parameters revealed that the martensitic substrate and vanadium carbide grains were finely and evenly scattered, consistent with the simulation results. This suggests that the simulation is a useful reference for guiding actual production. [ABSTRACT FROM AUTHOR]

The depths of crustal reservoirs within volcanic systems may experience transitions over time. Here, we report the crystal and bulk rock compositions of the shield-forming basaltic lavas of the Tianchi composite volcano in the intraplate Changbaishan Volcanic Field, NE China, to constrain crustal magmatic evolution with time. We investigated samples covering the entire basaltic stratigraphic sequence, consisting of the Toudao (TD), Baishan (BS), and Laofangzixiaoshan (LFZ) units from bottom to top, respectively. The core compositions of olivine macrocrysts vary among the three units, i.e., the TD and BS olivine phenocrysts can be divided into two populations: a high-Fo population (~Fo76–80) and a low-Fo population (~Fo72–74). The LFZ unit only exhibits a high-Fo population (~Fo77–80). Phase equilibria modeling using rhyolite-MELTS suggests that the high-Fo populations were stored at depths of ~20 km for the TD and BS units and ~15 km for the LFZ unit. The low-Fo populations crystallized at shallow depths, i.e., 15 km for the TD unit and 13 km for the BS unit. We employ dynamic Fe-Mg interdiffusion modeling with constantly adapting boundary conditions in zoned olivine macrocrysts to constrain the magmatic environments and timescales during the pre- and posteruption phases, enabling us to clarify the magmatic histories recorded by the two olivine populations. The dynamic Fe-Mg interdiffusion modeling considers the variable boundary conditions caused by crystal growth and composition variations of melts during magma cooling. Calculated results suggest that the high-Fo populations from the TD and BS units recorded prolonged timescales ranging from six months to more than two years with lower cooling rates and slower crystal growth rates. These characteristics reflect a relatively hot and slow-cooling magmatic environment, and the modeled timescales correspond to the sum of the time, including shallow storage, magma ascent, and further cooling within the lava flows. Conversely, the high-Fo population from the LFZ unit and the low-Fo populations from the TD and BS units record shorter timescales (<140 days) with higher cooling rates and faster crystal growth rates. These results indicate relatively cold and highly undercooled magmatic environments; hence, the timescales record magma ascent in the conduits and further cooling during lava emplacement. Our study demonstrates that the Tianchi basaltic plumbing system experienced a structural transition over time. In detail, the TD and BS magmas experienced multi-stage stalling and ascent, first accumulating in deep reservoirs and then ascending to shallow reservoirs for storage before the eruption. The LFZ magmas accumulated in a mid-crustal reservoir, followed by a direct ascent to the surface without additional residence. [ABSTRACT FROM AUTHOR]

Twenty-five years ago, Hancock and Parks asked a provocative question: "what is the true solubility advantage for amorphous pharmaceuticals?" Difficulties in determining the amorphous solubility have since been overcome due to significant advances in theoretical understanding and experimental methods. The amorphous solubility is now understood to be the concentration after the drug undergoes liquid-liquid or liquid-glass phase separation, forming a water-saturated drug-rich phase in metastable equilibrium with an aqueous phase containing molecularly dissolved drug. While crystalline solubility is an essential parameter impacting the absorption of crystalline drug formulations, amorphous solubility is a vital factor for considering absorption from supersaturating formulations. However, the amorphous solubility of drugs is complex, especially in the presence of formulation additives and gastrointestinal components, and concentration-based measurements may not indicate the maximum drug thermodynamic activity. This review discusses the concept of the amorphous solubility advantage, including a historical perspective, theoretical considerations, experimental methods for amorphous solubility measurement, and the contribution of supersaturation and amorphous solubility to drug absorption. Leveraging amorphous solubility and understanding the associated physicochemical principles can lead to more effective development strategies for poorly water-soluble drugs, ultimately benefiting therapeutic outcomes. [Display omitted] [ABSTRACT FROM AUTHOR]

The present study focused on the phase equilibria in the PbO‐CaO‐AlO1.5 and PbO‐CaO systems in air. The high‐temperature phase equilibria in these systems were studied using the high‐temperature equilibration and quenching technique. The compositions of phases present in the quenched samples were then measured using the electron probe X‐ray microanalysis. The liquidus of the PbO‐CaO‐AlO1.5 system in air, including Ca3Al2O6, Ca12Al14O33, (Ca,Pb)Al2O4, CaAl4O7, (Ca,Pb)Al12O19, Ca2PbO4, corundum (Al2O3), lime (CaO), massicot (PbO), Pb9Al8O21, PbAl2O4, and PbCa2Al8O15 primary phase fields as well as the immiscibility gap in the liquidi of Ca3Al2O6, Ca12Al14O33, and (Ca,Pb)Al2O4 have been experimentally characterized. The experimental data obtained were used for the thermodynamic optimization of a self‐consistent set of parameters of the thermodynamic model for all phases of the PbO‐CaO‐AlO1.5 system in air, in agreement with the Cu‐Pb‐Zn‐Fe‐Ca‐Si‐Al‐Mg‐O‐S‐(As, Sn, Sb, Bi, Ag, Au, Ni, Cr, Co, and Na) gas/oxide liquid/matte/speiss/metal/solids system in support of the development and optimization of pyrometallurgical processes. The predicted liquidus projection of the PbO‐CaO‐AlO1.5 system was presented for the first time in the complete range of temperatures and compositions. [ABSTRACT FROM AUTHOR]

Salt lakes are a rich source of metals used in various fields. Rubidium is found in small amounts in salt lakes, but extraction technology on an industrial scale has not been developed completely. Clathrate hydrates are crystalline compounds formed by the encapsulation of guest molecules in cage-like structures made of water molecules. One of the most important properties for engineering practices of hydrate-based technologies is the comprehension of the phase equilibrium conditions. Phase equilibrium conditions of CO2 hydrate in rubidium chloride aqueous solution with mass fractions of 0.05, 0.10, 0.15 and 0.20 were experimentally investigated in the pressure range from 1.27 MPa to 3.53 MPa, and the temperature was from 268.7 K to 280.6 K. The measured equilibrium temperature in this study decreased roughly in proportion to the concentration of the RbCl solution from the pure water system. This depression is due to the lowering of the chemical potential of water in the liquid phase by the dissolution of RbCl. Experimental results compared with other salt solution + CO2 hydrate systems showed that the equilibrium temperatures decreased to a similar degree for similar mole fractions. [ABSTRACT FROM AUTHOR]

Our students are digital natives and smartphones are part of their identity. However, the use of mobile devices in the classroom continues to be a non-integrated issue. For academic purposes, teaching actions involving smartphone apps expressly linked to student participation could be an opportunity to improve their performance. Under this premise, the use of the Quizizz app as a way of enhancing the flipped classroom methodology is herein proposed. The reported experience took place within a mass transfer separation course, at the Master level, during the academic courses 2021–22 and 2022–23. Enhanced distillation, a topic that is instrumental to future professionals in the field of Chemical Engineering, was addressed. It was found that the proposed approach allowed the students to better interpret the vapor-liquid and vapor-liquid-liquid phase equilibrium diagrams. Hence, the students demonstrated more skilled performance when they were asked to propose suited separation schemes (complex fractional distillation) using the Aspen Plus process simulator. Such success was not only in terms of deeper understanding but also on the observed predisposition towards autonomous learning. [Display omitted] • Gamification was found to enhance previous autonomous work at home. • Deeper understanding of phase equilibrium diagrams yielded better process simulations. • McCabe diagrams were more difficult to interpret than T-x,y diagrams. • Multiple choice questions based on a visual environment helped capture the students' attention. [ABSTRACT FROM AUTHOR]

Copyright of Special Steel is the property of Daye Special Steel Co. Ltd. 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.)

Despite its importance, the Ag-Cu-Te system's phase diagram remains poorly understood. This study addresses this gap by investigating the equilibrium phases in equilibrated Ag-Cu-Te alloys. Combining these experimental results with existing literature and the phase diagrams of the Ag-Cu, Ag-Te, and Cu-Te binary systems, the isothermal sections of the Ag-Cu-Te ternary phase equilibria at 600 °C and 400 °C are proposed. The phase diagrams of the binary systems, Ag-Te and Cu-Te, were reassessed. In the Ag-Te binary system, there are three compounds, Ag2Te, Ag1.9Te, and Ag5Te3. There are three binary compounds, Cu2Te, Cu3Te2, and CuTe, in the binary Cu-Te system. Ag and Cu whiskers were discovered along the Cu-Cu2Te-Ag2Te-Ag section, which prevented the determination of phase equilibria results in this region. One ternary compound, AgCuTe, was identified in the system. There are six and nine three-phase regions at 600 °C and 400 °C, respectively. There are limited Ag solubilities in the Cu3Te2 and CuTe 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 reservoir fluid PVT model is necessary to all types of hydrodynamic modelling (field development, well flow, well test, basin modelling, etc.). The PVT model, when not properly tuned, can result in significant inaccuracies in calculating PVT properties and field production of volatile oil and gas-condensate systems. The process of tuning the reservoir fluid PVT model is a complex and time-consuming task. Various methods, such as regression and machine learning (ML), have been employed for reservoir oil PVT model tuning; however, a definitive approach has not yet been identified. This paper introduces a novel and efficient step-by-step approach for developing and tuning reservoir fluid PVT which enables engineers to tune PVT models much faster than before. The new proposed approach can assist in the initialisation of a PVT model by employing effective methods for initial data pre-processing. Furthermore, it can accurately reproduce the results obtained from field measurements and basic laboratory studies conducted on representative samples, in a model using a cubic equation of state. Tuning the PVT model enables the reliable modelling of the PVT properties of all five types of reservoir fluids (black oil, volatile oil, gas condensate, wet gas, dry gas) in various applications; the applications include the design and monitoring of field development, multiphase flow calculations in wells and field pipelines, and basin modelling. It is possible to algorithmise and automate the application of this approach in specialised software. This study considered eight Russian reservoir oil and gas-condensate systems, for which the PVT models were tuned, using the proposed approach. The comparison between proposed approach and other tuning methods in modern PVT simulators (PVTi, PVTsim, Multiflash, PVT Designer) is shown in the article. These examples show the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

Copyright of Chemical Engineering (China) / Huaxue Gongcheng is the property of Hualu Engineering Science & Technology Co Ltd. 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.)

Mixing Gibbs energy and phase equilibria of aqueous solutions of polyglycine were studied theoretically by means of polymer reference interaction site model integral equation theory combined with the Gibbs–Duhem method. In addition to the ordinary liquid–liquid phase separation between dilute and concentrated solutions, the theoretical calculation predicted the coexistence of two coacervate phases, namely, the lower- and higher-density coacervates. The relative thermodynamic stabilities of these two phases change with the polymerization degree of polyglycine. The higher-density coacervate phase was rapidly stabilized by increasing the polymer length, and the lower-density phase became metastable at large polymers. The hydrogen bonds between the peptide chains were strengthened, and water was thermodynamically destabilized in the higher-density coacervate. A possible relation with the formation of amyloid fibril within a liquid droplet is also discussed. [ABSTRACT FROM AUTHOR]

Natural gas hydrates, mainly existing in permafrost and on the seabed, are expected to be a new energy source with great potential. The exploitation technology of natural gas hydrates is one of the main focuses of hydrate-related studies. In this study, a large-size liquid aqueous solution wrapping a methane hydrate system was established and molecular dynamics simulations were used to investigate the phase equilibrium conditions of methane hydrate at different methane concentrations and interfacial geometries. It is found that the methane concentration of a solution significantly affects the phase equilibrium of methane hydrates. Different methane concentrations at the same temperature and pressure can lead to hydrate formation or decomposition. At the same temperature and pressure, in a system reaching equilibrium, the size of spherical hydrate clusters is coupled to the solution concentration, which is proportional to the Laplace pressure at the solid–liquid interface. Lower solution concentrations reduce the phase equilibrium temperature of methane hydrates at the same pressure; as the concentration increases, the phase equilibrium temperature gradually approaches the actual phase equilibrium temperature. In addition, the interfacial geometry of hydrates affects the thermodynamic stability of hydrates. The spherical hydrate particles have the highest stability for the same volume. Through this study, we provide a stronger foundation to understand the principles driving hydrate formation/dissociation relevant to the exploitation of methane hydrates. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In oil and gas reservoirs with significant hydrocarbon columns the dependency of the initial hydrocarbon composition on depth – the compositional gradient – is an important factor in assessing the initial amounts of components in place, the position of the gas-oil contact, and variations of fluid properties throughout the reservoir volume. Known models of the compositional gradient are based on thermodynamic relations assuming a quasi-equilibrium state of a multi-component hydrodynamically connected hydrocarbon system in the gravity field, taking into account the influence of the natural geothermal gradient. The corresponding algorithms allow for calculation of changes in pressure and hydrocarbon fluid composition with depth, including determination of the gas-oil contact (GOC) position. Above and below the GOC, the fluid state is considered single-phase. Many oil-gas-condensate reservoirs typically have a small initial fraction of the liquid hydrocarbon phase (LHC) – scattered oil – within the gas-saturated part of the reservoir. To account for this phenomenon, a special modification of the thermodynamic model has been proposed, and an algorithm for calculating the compositional gradient in a gas condensate reservoir with the presence of LHC has been implemented. Simulation cases modelling the characteristic compositions and conditions of three real oil-gas-condensate fields are considered. The results of the calculations using the proposed algorithm show peculiarities of variations of the LHC content and its impact on the distribution of gas condensate mixture composition with depth. The presence of LHC leads to an increase in the level and possible change in the type of the fluid contact. The character of the LHC fraction dependency on depth can be different and is governed by the dissolution of light components in the saturated liquid phase. The composition of the LHC in the gas condensate part of the reservoir changes with depth differently than in the oil zone, where the liquid phase is undersaturated with light hydrocarbons. The results of the study are significant for assessing initial amounts of hydrocarbon components and potential efficiency of their recovery in gas condensate and oil-gas-condensate reservoirs with large hydrocarbon columns.

AbstractAsphaltene deposition and permeability damage due to CO2 injection pose significant challenges to the development of low-permeability reservoirs. This study conducted CO2-crude oil phase equilibrium tests and performed CO2 flooding and CO2 huff and puff experiments using long cores to analyse the recovery and asphaltene deposition characteristics of low-permeability reservoirs under different CO2 injection methods. The findings reveal that the recovery of CO2 flooding experiments at 8 MPa (immiscible), 16 MPa (miscible), and 24 MPa (miscible) representing improvements of 10.83% (±0.6%), 20.98% (±0.84%), and 22.5% (±1.05%) compared to CO2 huff and puff. The dynamic deposition rates of asphaltene after CO2 flooding mark decreases of 27.74% (±1.48%), 15.3% (±1.38%), and 13.6% (±1.26%) compared to CO2 huff and puff. However, the permeability damage rates of cores after CO2 flooding were 9.31% (±1.33%), 15.22% (±1.95%), and 19.44% (±1.38%) higher than those of CO2 huff and puff, respectively, and asphaltene deposits were more uniformly distributed in the long core after CO2 flooding. In addition, this study found that the asphaltene plugging, accounting for over 75% of the permeability damage after CO2 flooding, was the primary mechanism. In contrast, both asphaltene plugging and deposition contributed to permeability damage after CO2 huff and puff, with plugging being more prominent near the injection end after CO2 huff and puff, gradually decreasing along the direction of CO2 injection. Therefore, asphaltene plugging is the primary mechanism causing permeability damage in CO2 flooding, while both plugging and deposition play important roles in permeability damage after CO2 huff and puff. [ABSTRACT FROM AUTHOR]

ABSTRACT Robust quantification of the prograde P–T trajectories of eclogite exhumed from subduction zones is fundamental for deciphering the thermal structure evolution and understanding the geodynamic processes during continental subduction. In this study, we investigate four metabasites located in Hong'an within the western Dabie HP/UHP metamorphic belt. Based on detailed petrographic observations and mineral chemistry analyses, combined with phase equilibrium modelling, average‐T calculation and conventional thermobarometry, we quantify the prograde to peak P–T paths for each of the four metabasites and the retrograde P–T conditions for two samples. The results show that three of the four metabasites have similar prograde P–T paths evolving from 15.5–18.5 kbar, 440–485 °C (M0 stage) to 18.5–20.5 kbar, 500–525 °C (M1 stage). On the other hand, although the fourth sample shares a similar P–T evolution for a segment of the late prograde stage from 18.0–19.0 kbar, ~500 °C to 20.0–22.0 kbar, ~550 °C, it attains Pmax at a notably higher pressure of ~26.0 kbar at 550–560 °C (M2 stage). During exhumation, we identify an early retrograde stage occurring at 9.0–12.5 kbar, 545–580 °C (M3 stage), followed by a later retrograde stage at 3.5–8.0 kbar, 540–580 °C (M4 stage). In combination with previous studies, we propose a common dual‐segmented P–T path for the late prograde evolution of the HP/UHP rocks in western Dabie. The initial segment exhibits a gentle slope with apparent geotherms of 7–8 °C/km, whereas the subsequent segment displays a steeper slope with apparent geotherms of 5–6 °C/km. We interpret the turning point at 20.0–23.0 kbar (corresponding to depths of 70–80 km) as marking the maximum decoupling depths (MDD) between the subducting slab and the overlying mantle wedge. Notably, this prograde dual‐segmented geotherm for eclogite in western Dabie and the corresponding MDD are similar to computational geodynamic models. [ABSTRACT FROM AUTHOR]

ABSTRACT The Neoarchean Era is a key period in Earth's history as it witnessed a significant pulse of crustal formation corresponding to the assembly of several cratons, potentially coeval with a transition in the global tectonic regime. Neoarchean metasedimentary subprovinces of the Superior Craton, the largest unreworked Archean craton on Earth, were formed shortly before its final assembly and cratonization, thus providing valuable insights into the tectonic style, thermal state and architecture prevailing during this key period. Among these, the Pontiac Subprovince is one of the most studied, yet has a largely debated geodynamic history. In its northern extent, metamorphosed turbiditic sequences display a southward succession of index minerals—biotite, garnet, staurolite, kyanite and sillimanite—that may be indicative of a Barrovian‐like metamorphic gradient. However, the origin and evolution of this apparent gradient and its link to Neoarchean tectonics remain unclear. New mapping of metamorphic isograds and zones, petrological and microstructural analyses, whole rock and mineral chemistry analyses and phase equilibria modelling are integrated to decipher the Pontiac Subprovince tectonothermal evolution. Our analysis indicates that the peak equilibrium assemblages from the garnet, staurolite and sillimanite/melt zones developed early to late relative to the main regional deformation event (D2) and its associated steeply dipping S2 schistosity. Garnet zone rocks recorded a burial‐heating path with peak P–T conditions at 8.1–8.2 kbar and 582°C–585°C, along a low T/depth ratio of ~20°C/km. In contrast, staurolite and sillimanite/melt zone rocks followed isobaric heating and isothermal decompression paths with peak P–T conditions at 5.9–6.1 kbar and 610°C–625°C and 6 kbar and 700°C, respectively, along a moderate T/depth ratio of ~30–33°C/km. Since there is clear D2 structural continuity across the metamorphic zones over ~12 km and metamorphism occurred pre‐ to post‐D2, we interpret that the diverse P–T paths and contrasting T/depth ratios likely represent a spatially heterogeneous thermal structure developed within a single coherent structural block during and shortly after the formation of the subvertical S2 schistosity. Such features are hardly compatible with either modern inverted or continuous Barrovian sequences—known for consistent P–T evolution paths and similar T/depth ratios—or with discontinuous sequences requiring diachronicity. Our findings therefore do not fully reconcile with the existing accretionary/collisional models for the Pontiac Subprovince, given differences in their predicted apparent thermal gradients, metamorphic evolution and structural patterns. Alternatively, our data more closely match predictions for a sagduction‐dominated vertical process, where high heat influx at the base of the crust causes pooling/diapiric ascent of voluminous S‐type plutons, bordered by sagging synclines. This process led to the development of steeply dipping tectonic fabrics and pre‐ to late‐kinematic mineral assemblages along diverse P–T paths at contrasting yet coeval T/depth ratios. Our study provides insights into the evolution of the southeastern Superior Craton and highlights the need to apply an integrated quantitative approach to decipher its thermal structure and constrain the likely geodynamic processes that operated in the Neoarchean. [ABSTRACT FROM AUTHOR]

Traditional methods for stimulating carbonate formations primarily rely on the use of highly reactive acids, such as hydrochloric acid (HCl), to create wormholes. However, the limitations of this approach in certain scenarios have prompted the exploration of alternative strategies. In this study, we investigate the synergistic potential between microemulsion and ethylenediaminetetraacetic acid (EDTA) for stimulating carbonate formations. Microemulsion systems were formulated using a nonionic surfactant, sec-butanol as a cosurfactant, xylene as the oily phase, and an aqueous solution of EDTA as the water phase. The microemulsions were characterized by phase equilibrium and rheological behavior. Coreflooding and static dissolution experiments were performed. We employ microCT imaging to evaluate the change in porosity in static dissolution experiments. The results reveal that microemulsions containing EDTA presented remarkable stability and were able to significantly enhance carbonate rock permeability up to 85%, indicating that dissolution occurred and the rock was stimulated. Analyses of microCT images on static dissolution experiments of Indiana limestones in reactive microemulsions indicate an increase in porosity, confirming the dissolution process. These findings highlight the synergistic effect of EDTA in microemulsion media for enhancing the rock permeability of carbonate formation as an alternative as low reactive system. [ABSTRACT FROM AUTHOR]

The phase equilibria information of the CaO–SbOx system in the range of 700–1580°C in air was obtained for the first time using quenching method and thermal analysis. The equilibrium phase compositions were determined using x‐ray diffraction and Scanning Electron Microscopy‐Energy Dispersion Spectrum. The invariant reaction temperatures were determined using thermogravimetry‐differential scanning calorimetry. A perovskite solid solution between Ca2Sb2O7 and CaO, designated as (Ca6Sb2O11)s.s, was observed. Within this solid solution, three polymorphic forms were identified: orthorhombic, tetragonal, and cubic. The transition temperatures between these polymorphic forms vary with compositional changes. Additionally, the crystal structure of cubic Ca6Sb2O11 was analyzed. CaSb2O6 was observed to decompose into Ca2Sb2O7, Sb4O6, and O2 above 1336 ± 5°C. The eutectic temperature of α‐Sb2O4 and CaSb2O6 was found to be 1220 ± 5°C. [ABSTRACT FROM AUTHOR]

Phase equilibria studies were undertaken on the "CuO 0.5 "-PbO-CaO system in equilibrium with Cu/Pb metal as part of the integrated experimental and thermodynamic modelling study of phase equilibria in the Cu-Pb-Zn-Fe-Ca-Si-Al-Mg-O-S-(As, Sn, Sb, Bi, Ag, Au, Ni, Cr, Co and Na) gas/oxide liquid/matte/speiss/metal/solids system in support of the development and optimisation of pyrometallurgical processes. The equilibration and quenching technique followed by the electron probe X-ray microanalysis (EPMA) was used in the present study. The primary phase fields of massicot (PbO), copper plumbite (Cu 2 PbO 2), cuprite (Cu 2 O) and lime (CaO) were experimentally characterised. The experimental data obtained in the present study, as well as available literature data on the phase equilibria and thermodynamics of the "CuO 0.5 "-PbO-CaO system in equilibrium with Cu/Pb were used for the optimisation of the model parameters of the discussed system in agreement with the Cu-Pb-Zn-Fe-Ca-Si-Al-Mg-O-S-(As, Sn, Sb, Bi, Ag, Au, Ni, Cr, Co and Na) gas/oxide liquid/matte/speiss/metal/solids system to obtain a self-consistent set of parameters of the thermodynamic model for all phases. The predicted liquidus surface of the "CuO 0.5 "-PbO-CaO system was presented for the first time in the complete range of temperatures and compositions. [ABSTRACT FROM AUTHOR]

High-entropy alloys (HEAs) with ultrafine grained and high strength can be prepared by mechanical alloying (MA) followed by sintering. Therefore, MA, as a unique solid powder processing method, has many effects on the microstructures and mechanical properties of the sintered bulk HEAs. This work focused on the alloying behavior, morphology, and phase evolution of FexCrNiAl (x = 1.0, 0.5, 0.25) HEAs by MA. The X-ray diffraction results show that the powders achieved a supersaturated solid solution body-centered-cubic (BCC) phase after MA; the crystalline size reached the nanoscale and was refined to ~80 nm. The morphology and composition of the alloyed powders were studied by scanning electron microscopy with energy dispersive spectroscopy. The results indicate that the powder was decreased to 1.59 μm for Fe1.0 powder with excellent homogeneity in composition. There exists a phase transformation during high-temperature annealing, as the non-equilibrium BCC supersaturated solid solution phase transformed into the equilibrium phase of BCC and ordered BCC (B2) phases. [ABSTRACT FROM AUTHOR]

The phase rule of Gibbs is one of the basic equations in phase equilibria. Although it has been with us for 150 years, discussions, interpretations and extensions have been published. Here, the following new content is provided: (i). the choice of independent components is discussed, and the component rule is introduced, (ii). independent state variables are divided into compositional and non-compositional ones, (iii). the generalized phase rule is derived replacing number two in the original phase rule by the number of independent non-compositional state variables introduced above, (iv). the degree of freedom is decreased by the number of compositional constraints in special points (azeotrope and congruent melting) of phase diagrams, (v). a rule is derived connecting the maximum number of coexisting phases with the dimensions of the phase diagram, (vi). examples show how to apply the phase rule to unary, binary and ternary phase diagrams and their sections, (vii). the same is extended with the discussion of calculable and not calculable phase fractions, (viii). it is shown that the current definition of the degree of freedom is not sufficient in the number of cases, (ix). the current definition of the degree of freedom is extended, (x). the application of the generalized phase rule is demonstrated when other non-compositional state variables are applied for nano-phase diagrams, and/or for phase diagrams under the influence of electric potential difference, external magnetic field, mechanical strain or the gravitational field. [ABSTRACT FROM AUTHOR]

Using density functional theory (DFT), the electronic structure, lattice parameters, magnetic and thermodynamic properties of TlIn1–xCrxS2 with a monoclinic system were calculated. The influence of the degree of doping with chromium impurities on the properties of TlIn1–xCrxS2 supercells has been studied. Calculations were carried out using ab initio methods in the local electron density approximation (LDA) and in the generalized gradient approximation (GGA). Spin-orbit and Coulomb interactions were taken into account in DFT calculations. A change in the concentration of chromium impurity (x = 0.001–0.02) in TlInS2 does not lead to a change in the equilibrium lattice parameters and the type of magnetic ordering in TlIn1–xCrxS2. Phase equilibria and stability of binary and ternary compounds were studied by the thermodynamic method and the functional DFT GGA method in the Tl–In–S ternary system. The constructed isothermal section of the phase diagram at 298 K confirms the insignificant region of homogeneity, based on intermediate ternary compounds, of the Tl–In–S system.The formation energies of the compounds TlInS2 and TlIn1–xCrxS2 (x = 0.001–0.02) were calculated by the DFT method and are thermodynamically consistent with each other. The energy of formation of the TlInS2 compound, calculated by theoretical methods, is also consistent with experimental data. This indicates the adequacy of the calculation models used. In order to determine stable doping conditions, we analyzed the thermodynamic properties of the phases of the Tl–In–S system, established stable states of multicomponent phases, stable equilibria between binary and ternary compounds of the TlIn1–xCrxS2 system. Polycrystals were synthesized and TlIn1–xCrxS2 single crystals with different chromium impurity concentrations (x = 0, 0.001 and 0.02) were grown from them. The crystal structure, thermodynamic, dielectric, electrical and dosimetric characteristics of TlIn1–xCrxS2 single crystals were studied. The calculated thermodynamic and physical properties of the TlIn1–xCrxS2 phases are compared with experimental data. [ABSTRACT FROM AUTHOR]

This study presents a detailed flow-by-flow petrographic modal description and major element data integrated into the stratigraphic framework for the central part of the southeastern Ethiopian plateau (the Chole Section). The stratigraphic data are placed in the context of the regional stratigraphic framework and correlated with existing geochronology of the province, allowing us to estimate the timing and duration of volcanic activity in the area. Based on petrographic variations and physical volcanological features, the Chole section is divided into: (1) lower basalt; (2) middle basalt; and (3) upper basalt. The phase assemblages and major element data show that the lower and upper basalts underwent possible fractionation involving olivine, plagioclase, and augite. In contrast, the middle basalt equilibrium phase and major element data exhibits low-degree fractionation involving olivine, clinopyroxene, and orthopyroxene at greater depths. The stratigraphic position and the petrographic data suggests, the lower and middle basalt successions likely correlate with the Oligocene to Early Miocene basaltic succession (28–15.5 Ma) of the southeastern Ethiopian volcanic province. The presence of several volcanic hiatuses and the decrease in flow thickness in the middle basalt suggest a waning of magmatic activity during this period. The upper basalt of the Chole section correlates with the upper Miocene basalt of the southeastern volcanic province (15.5–11 Ma). From this, we determine that volcanic activity in the southeastern Ethiopian volcanic province is well constrained within the broader tectono-magmatic framework of the East African volcanic province. [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]

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]