This work presents the thermodynamic assessment of the Na+, K+, Mg2+ // Cl-, SO42- system, carried out through a combined experimental and modelling approach. Differential thermal analysis coupled with thermogravimetric analysis (DTA/TG), and differential scanning calorimetry (DSC) were employed to investigate phase equilibria and to determine key thermodynamic properties of the relevant subsystems. These experimental results provided a solid foundation for the development of a robust thermodynamic database, enabling accurate description of the system and reliable extrapolation to higher-order systems. Such predictive capability is particularly valuable for the screening and identification of promising candidates for phase change materials (PCMs). The three reciprocal subsystems (Na+, K+ // Cl-, SO42-; Na+, Mg2+ // Cl-, SO42-; K+, Mg2+ // Cl-, SO42-) of the multicomponent system were experimentally investigated and thermodynamically modelled based on the data presented in this work. In addition, the two ternary systems (NaCl-KCl-MgCl2; Na2SO4-K2SO4-MgSO4) were re-assessed, and the thermodynamic database was developed accordingly. In the framework of the PCM-Screening project, the low-melting compositions KCl(58.4 mol%)-MgSO4(41.6 mol%) and NaCl(66.4 mol%)-MgSO4(33.6 mol%) were experimentally characterised and their latent heats of fusion were measured to be 20.1 ± 0.4 kJ/mol and 42.0 ± 0.6 kJ/mol by DSC, respectively.

This work provides a comprehensive analysis of the reciprocal system Mg2+, Ca2+ // Cl- , SO42- , which was experimentally investigated using thermal analysis, calorimetric techniques, and structural characterisation, and thermodynamically modelled using the FactSage software. The study aimed to deepen the understanding of phase equilibria and thermodynamic behaviour within this system, with a particular focus on exploring its potential as high-temperature phase change materials (PCMs). Within the framework of the reciprocal system, the phase equilibria of the four binary systems (MgCl2-CaCl2, MgSO4-CaSO4, MgCl2-MgSO4, CaCl2-CaSO4) are presented alongside sections representing the ionic exchange reaction (MgCl2-CaSO4 and CaCl2-MgSO4). The experimental results on phase equilibria and thermodynamics of MgCl2-CaCl2, MgCl2-CaSO4 and CaCl2-MgSO4 systems supported the modelling work. Given the presence of the intermediate sulphate-based compound CaMg2(SO4)3, the phase equilibria in the quasi-binary systems involving this phase and the chlorides (MgCl2CaMg2(SO4)3 and CaCl2-CaMg2(SO4)3) were experimentally investigated. Based on all experimental findings, the Gibbs energy dataset in the reciprocal system Mg2+, Ca2+ // Cl-, SO42- was generated and presented in this study, contributing to the development and refinement of the thermodynamic database of inorganic salts, and providing valuable insights into the phase relationships and thermochemical behaviour of the reciprocal system.

This study aims to provide a comprehensive investigation of the reciprocal system Na+, Ca2+ // Cl-, SO42- by integrating experimental analysis with thermodynamic modelling. The experimental approach involved the complementary use of Differential Thermal Analysis/Thermogravimetry (DTA/TG), Differential Scanning Calorimetry (DSC), and High-Temperature X-ray Diffraction (HT-XRD). These techniques provided essential experimental evidence for the phase equilibria description and served as a foundation for thermodynamic modelling. The reciprocal system was examined within the framework of phase change material (PCM) screening and identification for thermal energy storage applications. Based on the results obtained in this work, the thermodynamic database was developed for the aforementioned salt system. Notably, experimental findings highlighted significant modifications in the description of the binary system Na2SO4-CaSO4, namely the formation of the solid solution based on the high temperature modification of Na2SO4 and the identification of intermediate compounds Na4Ca(SO4)3, which replaces the previously assumed Na6Ca(SO4)4 compound. Additionally, while Na2Ca(SO4)2 had already been reported in prior studies, this work has provided a more precise definition of its thermal stability window, based on new experimental evidence. Furthermore, the experimental study of the NaCl-CaSO4 and CaCl2-Na2SO4 systems, representing the ionic exchange reaction, enabled a more detailed investigation of the reciprocal system, contributing to an improved thermodynamic description within the current database. This study reports, for the first time, the enthalpy of fusion of the eutectic composition in the NaCl-CaSO4 system, determined to be 39.3 ± 1.7 kJ/mol, with a corresponding melting temperature of 724 °C (997 K). Through the thermodynamic assessment of the sub-systems investigated both in this study and in previous works, an updated thermodynamic database has been developed, providing a comprehensive description of the entire reciprocal system and enabling a more accurate estimation of eutectic compositions within it. These findings enhance the accuracy of phase equilibria modelling and provide valuable insights into the thermal properties of potential PCM candidates.

This study aims to provide a comprehensive investigation of the reciprocal system Na+, Ca2+// Cl-, SO42- by integrating experimental analysis with thermodynamic modelling. The experimental approach involved the complementary use of Differential Thermal Analysis/Thermogravimetry (DTA/TG), Differential Scanning Calorimetry (DSC), and High-Temperature X-ray Diffraction (HT-XRD). These techniques provided essential experimental evidence for the phase equilibria description and served as a foundation for thermodynamic modelling. The reciprocal system was examined within the framework of phase change material (PCM) screening and identification for thermal energy storage applications. Based on the results obtained in this work, the thermodynamic database was developed for the aforementioned salt system. Notably, experimental findings highlighted significant modifications in the description of the binary system Na2SO4-CaSO4, namely the formation of the solid solution based on the high temperature modification of Na2SO4 and the identification of intermediate compounds Na4Ca(SO4)3, which replaces the previously assumed Na6Ca(SO4)4 compound. Additionally, while Na2Ca(SO4)2 had already been reported in prior studies, this work has provided a more precise definition of its thermal stability window, based on new experimental evidence. Furthermore, the experimental study of the NaCl-CaSO4 and CaCl2-Na2SO4 systems, representing the ionic exchange reaction, enabled a more detailed investigation of the reciprocal system, contributing to an improved thermodynamic description within the current database. This study reports, for the first time, the enthalpy of fusion of the eutectic composition in the NaCl-CaSO4 system, determined to be 39.3 +/- 1.7 kJ/mol, with a corresponding melting temperature of 724 degrees C (997 K). Through the thermodynamic assessment of the sub-systems investigated both in this study and in previous works, an updated thermodynamic database has been developed, providing a comprehensive description of the entire reciprocal system and enabling a more accurate estimation of eutectic compositions within it. These findings enhance the accuracy of phase equilibria modelling and provide valuable insights into the thermal properties of potential PCM candidates.

In this study, the Li2CO3–Na2CO3 system was investigated experimentally and a new thermodynamic dataset for this system was established using the CALPHAD approach. Thermodynamic data from literature were collected and critically analyzed. The phase equilibria of this system were further investigated experimentally by Differential Thermal Analysis (DTA) measurements and High temperature X-ray Diffractometry (HTXRD): three solid solution phases based on three solid modifications of pure Na2CO3 were determined. The heat capacity of Na2CO3 and the intermediate compound LiNaCO3 was obtained experimentally by three types of Differential Scanning Calorimeter (DSC) devices. The Gibbs energies of the studied compounds and solutions were evaluated using available literature data together with our experimental results. The new dataset for the Li2CO3–Na2CO3 system can improve the accuracy of phase diagram calculations and the prediction of thermodynamic properties for various applications.

Porous architectures with a high strength-to-weight ratio, large surface area, and high resilience have recently garnered interest for applications in gas storage, battery electrodes, and fuel cells. These materials' desired properties can be achieved by tuning pore characteristics, such as wall thickness, pore size, and pore directionality, and by using various constituent materials. Another important application of such materials is carbon dioxide capture, which helps mitigate global warming caused by rising atmospheric CO2 levels. In this study, a hierarchical structure with controlled pore direction was fabricated through directional freeze-casting using different types of bio-nanofibers from nature, such as cellulose, chitin, or chitosan. These free-standing structures with controlled pore orientation were then pyrolyzed at 700 degrees C, resulting in free-standing carbon with controlled pore direction. The carbonized structure made from chitosan nanofiber demonstrated a CO2 capture performance up to 13 times higher than its powder-type counterpart, with stable cyclability.

This work provides a comprehensive analysis of the reciprocal system Mg2+, Ca2+ // Cl−, SO42−, which was experimentally investigated using thermal analysis, calorimetric techniques, and structural characterisation, and thermodynamically modelled using the FactSage software. The study aimed to deepen the understanding of phase equilibria and thermodynamic behaviour within this system, with a particular focus on exploring its potential as high-temperature phase change materials (PCMs). Within the framework of the reciprocal system, the phase equilibria of the four binary systems (MgCl2-CaCl2, MgSO4-CaSO4, MgCl2-MgSO4, CaCl2-CaSO4) are presented alongside sections representing the ionic exchange reaction (MgCl2-CaSO4 and CaCl2-MgSO4). The experimental results on phase equilibria and thermodynamics of MgCl2-CaCl2, MgCl2-CaSO4 and CaCl2-MgSO4 systems supported the modelling work. Given the presence of the intermediate sulphate-based compound CaMg2(SO4)3, the phase equilibria in the quasi-binary systems involving this phase and the chlorides (MgCl2-CaMg2(SO4)3 and CaCl2-CaMg2(SO4)3) were experimentally investigated. Based on all experimental findings, the Gibbs energy dataset in the reciprocal system Mg2+, Ca2+ // Cl−, SO42− was generated and presented in this study, contributing to the development and refinement of the thermodynamic database of inorganic salts, and providing valuable insights into the phase relationships and thermochemical behaviour of the reciprocal system.

Thermodynamic properties of MgCl2-MgSO4 and CaCl2-CaSO4 binary systems hold significant importance in the exploration of potential phase change materials for thermal energy storage applications. This study aims to elucidate the phase diagrams and thermodynamic properties of the eutectic mixtures within these systems, employing experimental techniques such as Differential Thermal Analysis (DTA) and Differential Scanning Calorimetry (DSC). Through comprehensive experimental investigations, the phase diagrams of the MgCl2-MgSO4 and CaCl2-CaSO4 systems were meticulously delineated, revealing the eutectic compositions and transition temperatures. Specifically, the eutectic composition for MgCl2-MgSO4 was proposed to be 28.0 mol% MgSO4 with a melting temperature of 663 +/- 5 degrees C, while for the CaCl2-CaSO4 system it was found to be at 14.0 mol% CaSO4 and 722 +/- 5 degrees C. Additionally, the enthalpy of fusion of these eutectic mixtures was for the first time determined, providing crucial insights into their thermal behaviour. They are 38.2 +/- 1.0 kJ/mol for the Mg-containing system and 30.2 +/- 0.4 kJ/mol for the Ca-containing system, respectively. The experimental data obtained in this study served as the foundation for the development of a new Gibbs energy dataset, which is essential for conducting thermodynamic calculations. The utilisation of this dataset enables accurate predictions of thermodynamic properties across the entire composition and temperature ranges of the systems under investigation.

This work presents a comprehensive experimental investigation into the thermal properties of the binary system MgSO4-CaSO4, alongside thermodynamic modelling of its thermodynamic properties, with a focus on enhancing its application in thermal energy storage. The phase diagram and thermodynamic properties of the pure sulphates and intermediate compounds were determined using Differential Thermal Analysis (DTA) and Differential Scanning Calorimetry (DSC). The DSC results led to the refinement of the enthalpy values for phase transitions of MgSO4, with updated values of 14.6 kJ/mol and 43.4 kJ/mol for the solid-solid and solid-liquid transitions, respectively. High-Temperature X-ray Diffraction (HTXRD) was employed to study the intermediate compounds, leading to the identification of CaMg2(SO4)3. For the first time, the melting temperature and the enthalpy of fusion for this compound were experimentally determined, yielding a value of 145.5 kJ/mol at 1213 +/- 5 degrees C. A novel phase with the composition CaMg(SO4)2 was identified using DTA, HTXRD, and Scanning Electron Microscopy (SEM). This phase exhibits a melting temperature of 1309 +/- 5 degrees C, as determined by DTA, and demonstrates thermal stability within a high-temperature range of 1020-1308 degrees C. These experimental data were used to update the thermodynamic database for the system MgSO4-CaSO4 for more accurate thermochemical calculations and predictions.

Inorganic halide perovskites have become attractive for many optoelectronic applications due to their outstanding properties. While chemical synthesis techniques have been successful in producing high-quality perovskite crystals, scaling up to wafer-scale thin films remains challenging. Vapor deposition methods, particularly physical vapor deposition and chemical vapor deposition, have emerged as potential solutions for large-scale thin film fabrication. However, the control of phase purity during deposition remains problematic. Here, we investigate single-source (CsPbBr3) and dual-source (CsBr and PbBr2) physical vapor deposition techniques with the aim of achieving phase-pure CsPbBr3 thin films. Utilizing Knudsen effusion mass spectrometry, we demonstrate that while the single-source CsPbBr3 evaporation is partially congruent, it leads to compositional changes in the evaporant over time. The dual-source evaporation, with a precise control of the PbBr2/CsBr flux ratio, can improve phase purity, particularly at elevated substrate temperatures under excess PbBr2 conditions. Our results give direct evidence that the growth is CsBr-limited. Overall, our findings provide critical insights into the vapor phase deposition processes, highlighting the importance of evaporation conditions in achieving the desired inorganic perovskite stoichiometry and morphology.

The binary system La2O3-WO3 was thermodynamically assessed using the available experimental information on phase equilibria and thermodynamic properties of binary lanthanum tungstates. The Gibbs energies of eight compounds (La2O3)m(WO3)nwere for the first time generated based on thermal (Differential Thermal Analysis-DTA), calorimetrical and EMF (Electro-motive force) measurements from the literature. The melting temperature of the compound La6W2O15 was determined by high-temperature dilatometry. The modified associate species model was successfully applied for description of the liquid phase. The solid solution based on the compound La10W2O21 (called LaWO) with defective fluorite type structure shows promising conductive properties and can be applied as proton conductor in various electrochemical devices. Therefore, this phase was included in the dataset and modelled using a multi-sublattice model. The calculations on phase equilibria and thermodynamic properties are in good agreement with the available experimental data. The dataset obtained can be used for calculations of the thermodynamic stability of the relevant ceramic phases in order to predict the properties of the complex systems containing functional materials and environmental conditions (temperature, chemical compositions).

To support the sustainable industrialization of solid oxide cell (SOC) stacks, the present study proposes and experimentally validates a recycling pathway to recover interconnect assemblies from end-of-life J & uuml;lich SOC stacks. The recycling process utilizes scrap-based steelmaking operations to produce steels with comparable chemical composition, microstructure, and hardness to commercial-grade AISI 304 steels. Results from smelting demonstrate a high metal yield of 95.7% and controlled deportation of metallic resources into the slag phase. X-ray computed tomography analysis of the slag shows metal inclusions with sizes less than 1.7 mm and accounting for approximate to 2.01 vol% of the slag. Furthermore, the slag contains a relatively high amount of chromium (3.61 wt% Cr), and minor amounts of iron (1.02 wt% Fe) and manganese (0.90 wt% Mn). Subsequent refinement and heat treatment of the smelted alloy have successfully produced austenitic steel with less than 4.0% delta-ferrite area fraction. Microindentation tests confirm that its hardness values are consistent with the typical values for AISI 304 steels. Furthermore, high-temperature X-ray diffraction analyses provide valuable insights into the recycled steel's relative austenite stability regions. Finally, potential challenges and opportunities associated with scaling up the proposed recycling route are discussed.

High entropy alloys (HEAs) are solid solution alloys containing at least 5 elements in equiatomic or near-equiatomic composition. In the present study we report on an alloy design route for refractory HEAs based on Mo-Nb-V-xTi alloys (x denotes mole per cent of Ti, x = 5, 10, 15, 20, 25, the mole per cents of Mo, Nb, and V are equal). The thermodynamic activities of Ti and V were determined by Knudsen effusion mass spectrometry and the measured data were compared to the calculated data obtained by CALPHAD method.

Salts and their mixtures play an important role for industrial and energy sectors, eg metallurgy, biomass gasification and combustion, nuclear and solar powerplants and electrochemical processes. Depending on the composition of salts (eg Li+, Na+, K+, Mg2+, Ca2+ // NO3-, F-, Cl-, CO32-, SO42-, etc), the temperature range for different applications can vary starting from room temperature and going up to 1500°C. For the proper design and modelling of heat exchangers and other equipment, it is necessary to have reliable and validated data sets of thermophysical properties. The 50 mol per cent NaNO3 – 50 mol per cent KNO3 salt mixture as a well-studied composition was selected for validation of relevant thermophysical properties (heat capacity, enthalpy of phase transitions, thermal expansion, viscosity and thermal conductivity). To study these properties of the liquid phase, special crucibles and approaches should be implemented. Verification of these crucibles for different methods (differential scanning calorimetry (DSC), thermomechanical analysis (TMA), laser flash analysis (LFA) and rheometers) has been performed. The low thermal conductivity of salts is one of the main problems in implementing latent heat storage. In this project, the authors intend to develop a fundamental solution to this problem using chemically bonded metals with salts. These are known as metal-salt solutions. To fit the main parameters of new phase change materials to the requirements of thermal energy storage, a wide variety of possible combinations should be considered. CALPHAD modelling is used together with thermal analysis for the development of a consistent thermodynamic database including chloride salts (Li, Na, K, Mg, Ca // Cl) and corresponding metals (Li, Na, K, Mg, Ca). The results of the study of quasi-binary and multicomponent metal-salt (eg Mg-KCl and Ca-KCl) systems as well as the selection of suitable crucible materials and challenges by studying of these systems will be discussed.

The present study provides fundamental information on the resource recyclability of the interconnect assembly, i.e., the steel interconnector and the nickel meshes, from an end-of-life JÜLICH Solid Oxide Cell Stack—F10 design. The interconnector is composed of iron, chromium, and less than 4 wt.% of other alloying elements, mainly cobalt and manganese. Calculated blended compositions with the nickel meshes revealed their potential as a raw material in the production of 4xx, 2xx, or 3xx stainless steels. The melting behavior of the interconnect assembly was investigated under different conditions, i.e., in inert and oxidizing atmospheres, with and without the addition of slag-forming fluxes. The results demonstrated preferential oxidation of chromium in a trivalent state within the stable cubic spinel phase. Finally, the experimental results were compared with the thermodynamic equilibrium calculations based on the available databases (FToxid, SGTE, and SGPS) in FactSage 8.1 software. The calculated tendency to oxidize is in the order of Cr > Mn > Fe > Co > Ni at P(O2) greater than 10−10 bar, validating the experimental results.

Calcium and magnesium oxide are important components of metallurgical slag systems. However, the literature values for the standard enthalpy of formation Δ_fH_298^^∘ of both oxides exhibit large variations in some cases. Since Δ_fH_298^^∘ is crucial for the modeling and prediction of equilibrium states and, thus, also for process optimization; it was determined by Knudsen effusion mass spectrometry (KEMS). Pure CaO as well as MgO were investigated in an iridium Knudsen cell. For this purpose, the intensities of the main species present in the gas phase were recorded in a temperature range between 1825 K to 2125 K and 1675 K to 2075 K, respectively, and their partial pressures were obtained. It was observed that CaO and MgO evaporated congruently with the main species in the gas phase, Ca, Mg, O, and O 2 . The experimental vapor pressures of the gas species in the study of MgO are in good agreement with the calculated values using FactSage TM 7.3 and the FactPS database, while those for the evaporation of CaO show significant differences. These calculations are based on available thermodynamic information, including the Gibbs energy functions of CaO(s), Ca(g), MgO(s), Mg(g), O(g), and O 2 (g). After calculating the partial pressures and equilibrium constants of reactions, an average formation enthalpy of Δ_fH_298^^∘ = − 624.5 ± 3.5 kJ/mol for CaO(s) and Δ_fH_298^^∘ = − 598 ± 10 kJ/mol for MgO(s) based on the third law method of thermodynamics were obtained. The deviation of Δ_fH_298^^∘ for MgO from the previous literature values can be attributed to the use of different ionization cross sections, temperature calibration, and variation of tabulated Gibbs energy functions.

Inorganic halide perovskites have become attractive for many optoelectronic applications due to their outstanding properties. While chemical synthesis techniques have been successful in producing high-quality perovskite crystals, scaling up to wafer-scale thin films remains challenging. Vapor deposition methods, particularly physical vapor deposition and chemical vapor deposition, have emerged as potential solutions for large-scale thin film fabrication. However, the control of phase purity during deposition remains problematic. Here, we investigate single-source (CsPbBr3) and dual-source (CsBr and PbBr2) vapor deposition techniques to achieve phase-pure CsPbBr3 thin films. Utilizing Knudsen Effusion Mass Spectrometry, we demonstrate that while the single-source CsPbBr3 evaporation is partially congruent, it leads to compositional changes in the evaporant over time. The dual-source evaporation, with a precise control of the PbBr2/CsBr flux ratio, can improve phase purity, particularly at elevated substrate temperatures at excess PbBr2 conditions. Our results give direct evidence that the growth is CsBr-limited. Overall, our findings provide critical insights into the vapor phase deposition processes, highlighting the importance of evaporation conditions in achieving the desired inorganic perovskite stoichiometry and morphology.

BaCe0.65Zr0.2Y0.15O3-delta (BCZ20Y15) has raised great interest due to its good protonic conductivity and chemical stability. However, the sintering of the material is considerably challenged by its refractory nature. In the current work, almost fully densified single-phase BCZ20Y15 with grain sizes exceeding 10 mu m was successfully fabricated by sintering at 1500 degrees C by using calcined powders consisting of naturally separated perovskite phases and 0.5 wt % NiO. The role of NiO as sintering aid was elucidated by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) and Atom Probe Tomography (APT) methods, concerning global and local material composition. Furthermore, the mechanism leading to the promoted densification and grain growth is elucidated based on current experimental results and a comprehensive review of the literature.