Substitutional Solution Research Articles

Thermodynamic modeling of B–Mo–Nb ternary system with modified B–Nb description

Based on a critical evaluation of the literature data, the B–Mo–Nb ternary system has been assessed by means of the CALPHAD (CALculation of PHAse Diagrams) technique. There is no ternary compound reported in this system. According to their crystal structures, the substitutional solution is adopted to model the ternary liquid, and the sublattice models are used to describe the Mo2B, αMoB, (Mo,Nb)B, (Mo,Nb)B2, Mo2B5, MoB4, Nb3B2, Nb5B6, Nb3B4, Nb2B3, (Mo,Nb) and (B) phases. The modeling covers the whole composition and temperature ranges. Due to the same crystal structure, the sublattice model of the NbB phase in the B–Nb binary system is adjusted as (Me,Va)0.5(B,Va)0.5, in order to be consistent with the βMoB phase in the B–Mo binary system. The obtained thermodynamic parameters of the B–Mo–Nb system are demonstrated to be self-consistent and reasonable by adequately comparing the calculated and reported thermodynamic information and phase diagram. Based on the present thermodynamic parameters, the liquidus projection and reaction scheme of B–Mo–Nb system are presented.

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

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

6Ag2Se + Ag8GeTe6 ↔ 6Ag2Te + Ag8GeSe6 Reciprocal System

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

Measurement of mixing enthalpies for Bi-Zn lead-free solder system

Integral mixing enthalpy, partial mixing enthalpy & interaction parameters of the Bi-Zn alloys system has been calculated at 823 K and 923 K by using the drop calorimetric technique. This will help to predict the thermodynamic properties of multi-component systems by using values of interaction parameters of the Bi-Zn binary system. It is widely recognized that high concentrations of any elements can lead to toxicity; however, Sn and Zn are relatively less hazardous due to their essential roles in the human diet. Bi is low-risk metal with a history of medical use. So it may be a good replacement for lead-based solder alloys as lead is a very toxic element. Argon gas is used as a carrier and auxiliary gas to provide an inert atmosphere in the furnace. It is also visible that the enthalpy of mixing is asymmetrical with a composition of Zn. The integral enthalpy of mixing of the Bi-Zn system at 823 K and 923 K is endothermic in nature all through the composition, and its most value at xZn = 0.79 is 3717.035349 Jmol−1 and 3780.695484 Jmol−1 respectively. The theoretical Redlich-Kister polynomial substitutional solution model was applied to the data from these measurements in order to find the binary interaction parameter by least-square fitting. When the estimated and measured values are compared, it is found that there is a good agreement between them.

A Feasibility Study on Translation of RGB Images to Thermal Images: Development of a Machine Learning Algorithm

The thermal image is an important source of data in the fire safety research area, as it provides temperature information at pixel-level of a region. The combination of temperature value together with precise location information from thermal image coordinates enables a comprehensive and quantitative analysis of the combustion phenomenon of fire. However, it is not always easy to capture and save suitable thermal images for analysis due to several limitations, such as personnel load, hardware capability, and operating requirements. Therefore, it is necessary to have a substitution solution when thermal images cannot be captured in time. Inspired by the success of previous empirical and theoretical study of deep neural networks from deep learning on image-to-image translation tasks, this paper presents a feasibility study on translating RGB vision images to thermal images by a brand-new model of deep neural network. It is called dual-attention generative adversarial network (DAGAN). DAGAN features attention mechanisms proposed by us, which include both foreground and background attention, to improve the output quality for translation to thermal images. DAGAN was trained and validated by image data from fire tests with a different setup, including room fire tests, single item burning tests and open fire tests. Our investigation is based on qualitative and quantitative results that show that the proposed model is consistently superior to other existing image-to-image translation models on both thermal image patterns quality and pixel-level temperature accuracy, which is close to temperature data extracted from native thermal images. Moreover, the results of the feasibility study also demonstrate that the model could be further developed to assist in the analytics and estimation of more complicated flame and fire scenes based only on RGB vision images.

Grain-boundary segregation and grain growth in nanocrystalline substitutional solid solution alloys

A model for describing solute segregation at grain boundaries has been developed for substitutional solid solution alloys, which integrates multiple factors from atomic to microstructural scales. A concept of molar Gibbs free energy of segregation was introduced to evaluate the segregating capability of the solute elements in a closed system, through which the influences of grain boundary structure, grain size, material composition, and external conditions were described. Based on the evaluation of various energy forms related to solute segregation and grain growth processes, the nature of the thermal stabilization of nanograin structures by solute segregation was disclosed. A criterion for the destabilization of nanostructures, which is determined by the competition of the change rates between the molar Gibbs free energy of segregation and the total energy of grain boundaries with grain size, has been proposed. This study provided guideline to achieve high-temperature stability of nanograin structures of solid solution alloys even for the weakly segregating nanocrystalline systems.

Solubility in the Ternary Water–Salt System GdCl3–TbCl3–H2O at 25°С

The solubility diagram of the ternary system GdCl3–TbCl3–H2O is studied by means of isothermal saturation in ampules at 25°С. A continuous series of solid solutions of isovalent substitution crystallizes in the system GdxTb1−xCl3⋅6H2O.GdTb1−Cl3⋅6H2O. The diagram of solubility in the three-component system GdCl3–TbCl3–H2O at 25°C is calculated according to the classical Pitzer model. Results from experiments agree convincingly with ones from thermodynamic modeling.

Rationality of two-phase coexistence with no element segregation in a CuZr-based amorphous alloy composite

Here, the structure features of Cu62Zr34.4Al3Nb0.6 amorphous alloy composites (AACs) are studied by combining experimental characterization with first-principles calculation. Element segregation, which is common in conventional alloy materials, does not occur in two phases (crystalline and amorphous phase) of the AACs due to complex solid solution. The lattice parameters, electron distribution, charge transfer and electrical potential, which are directly related to atomic bonding and lattice parameters of different structures, are obtained by calculating the various types of structural models, including interstitial solid solution, substitutional solid solution, B2 and amorphous phase. Finally, the formation and stability of solid solution in crystalline phase and amorphous phase are elucidated by first-principles calculation. The work has important guiding significance for understanding the two-phase structure and solidification mechanism in AACs materials.

PHASE RELATIONS IN THE Ag8SiS6–Ag8SiTe6 SYSTEM AND CHARACTERIZATION OF SOLID SOLUTIONS

Argyrodite family compounds and phases based on them are valuable ecologically friendly functional materials that exhibit a number of functional propreties, such as thermoelectric, photoelectric, optical, and other. On the other hand, having Cu+ and Ag+ ion conductivity, they are ionic conductors, and can be used as electrochemical sensors, electrodes, or electrolyte materials in solid-state batteries, displays, etc. In the present paper, phase relations in the Ag8SiS6–Ag8SiTe6 system were studied by differential thermal analysis and X-ray diffraction phase techniques and a T-x phase diagram was constructed. It is established that the system is quasi-binary and is characterized by the formation of a continuous series of substitutional solid solutions between Ag8SiTe6 and HT- Ag8SiS6 compounds. With the formation of solid solutions, the temperature of the polymorphic transition of the Ag8SiS6 decreases. This leads to the stabilization of the ion-conducting cubic phase in the range of compositions 30 mol. % Ag8SiTe6 at room temperature and below. The homogeneity regions based on RT-Ag8SiS6 are 10 mol. %. According to XRD data, the crystal lattice parameters of the obtained solid solutions were calculated and a their linear dependence on the composition is shown

#6825 ECOLOGICAL APPROACH FOR KIDNEY REPLACEMENT THERAPY IN CRITICAL CARE: SLED MAY BE A STRATEGY

Abstract Background and Aims Dialysis has an enormous environmental impact, not only for disposable consumables, but also for the water and energy consumption. Despite increasingly evidence regarding comparable outcomes between continuous kidney replacement therapy (CKRT) and slow low efficiency dialysis (SLED), ecological-based endpoints are not frequently evaluated. Literature in critical care concerning the environmental impact of these techniques is scarce. We aimed to determine the waste production, water and energy consumption in SLED and CKRT and identify the technique with higher environmental impact. Method We conducted a cross-sectional, observational, single-center study in patients with acute kidney injury requiring kidney replacement therapy admitted to an intensive care unit (ICU). We analyzed the waste weight of each dialysis technique (Fresenius Medical Care 5008 for SLED and Baxter Prismaflex for CKRT) before and after the treatment. We estimated the water consumption of a SLED session with a Qd of 300 ml/min for 8 hours and 12 hours sessions, considering a Reverse Osmosis (RO) system with a 50% rate water rejection and a CKRT session for an 80Kg patient, with a Qd of 1300 mL/h and a reposition solution flow of 500 mL/h. Both techniques included a disinfection volume of 14 L. Results A SLED session produced 1600 g of waste (1200 g was hazardous and 400 g was non-hazardous waste). A CKRT session produced 2700 g of waste, not considering the substitution solution volume, which can vary up to a maximum of 15000 g/treatment. Waste consumables for each technique are discriminated in Table 1. The unpurified water consume of 8-hours and 12-hours SLED treatment was 237 L and 345 L, respectively. For CKRT, we estimated a consume of 43.2 L a day and 129.6 L for a 72-hour treatment. SLED had an energy consumption of 5.71 kW and 8.43 kW, for 8-hours and 12 hours treatment, respectively. The CKRT consumed about 12 to 14.4 kW per day. Conclusion Our study highlights the quantity of waste produced, water and power consumption of dialysis techniques in the critical patient. CKRT produces more hazardous waste, that generates a larger carbon footprint. Hazardous waste cannot be recyclable and implies specific management and disposal, which is more expensive and laborious than non-hazardous. CKRT has also a higher power consumption due to treatment duration and technology used to generate electricity. SLED has higher water consumption, nevertheless, current strategies used in hemodialysis units could also be implemented in UCI to minimize this effect. For example, the rejected water can be reused to agriculture and toilet flushing; more efficient water purification system with a lower proportion of rejected water can also reduce water consumption. SLED has unequivocal clinical benefits in the critical patient and, from an ecological perspective, seems to be a more sustainable option.

Multilayer amorphous-crystalline high-entropy metal films

High-entropy alloys (HEA) are multi-element materials and contain at least five elements of similar concentration. HEA are, as a rule, single- phase thermodynamically stable substitutional solid solutions, mainly based on a body-centered cubic and face-centered cubic crystal lattice. Solid solution stabilization during the crystallization of a high-entropy alloy is provided by the interaction of a number of factors, namely, a high mixing entropy and low diffusion rate of components, and a low growth rate of crystallites from the melt. The purpose of this work was to obtain new knowledge about the structure and properties of high-entropy films synthesized on a metal substrate during deposition of a multi-element metal plasma in argon atmosphere. The plasma was formed as a result of independent plasma-assisted electric arc cathodes of the following metals: Ti, Al, Cu, Nb, Zr sputtering. As a result of the performed studies, the deposition mode was revealed, which allows the formation of films of various thicknesses of close to equiatomic composition. Transmission electron microscopy methods have established that the films are multilayer formations and have nanoscale amorphous-crystalline structure. Microhardness of the films significantly depends on the ratio of number of the forming elements and varies from 12 to 14 GPa, Young’s modulus – from 230 to 310 GPa. Crystallization of the films was carried out by irradiation with a pulsed electron beam. As a result of processing, a two-phase state is formed. The main phase is α-NbZrTiAl with a volume-centered cubic crystal lattice with a parameter of 0.32344 nm; the second phase of CuZr composition has a simple cubic lattice.

The role of Cr, P, and N solutes on the irradiated microstructure of bcc Fe

The objective of this study is to understand irradiation-induced and assisted defect evolution in binary body center cubic (bcc) Fe-based alloys. The broader class of bcc ferritic alloys are leading candidates for advanced nuclear fission and fusion applications, in part due to their exceptional void swelling resistance. However, their irradiated microstructure evolution is sensitive to solute species present, since these solutes can act as traps for irradiation-induced defects due to the surrounding tensile or compressive stress fields. Here, three alloys (Fe-9.5%Cr, Fe-4.5%P, and Fe-2.3%N) are selected for study because they systematically exhibit varying solute sizes and solute positions (i.e., substitutional or interstitial). Ex situ and in situ ion irradiations reveal that Fe-P has a considerably finer and denser population of irradiation-induced defects than Fe-Cr and Fe-N at the same irradiation conditions, which is attributed to strong defect trapping at undersized substitutional P, consequently hindering the development of extended defects. Meanwhile, oversized substitutional solutes (e.g., Cr) and interstitial solutes (e.g., N) may also suppress dislocation loop development due to weak solute-defect trapping.

Phase relations in the Si–Sn–As system

The goal of this work was to study phase relations in the ternary Si–Sn–As system: to establish cross sections, to construct a scheme of phase equilibria, and to identify the temperature of non-variant transformations. Ternary alloys were obtained through direct synthesis from simple substances and subjected to long-term solid-phase annealing. Alloys of four polythermal sections of the Si–Sn–As system were examined using X-ray phase and differential thermal analysis. The results of X-ray powder diffraction allowed establishing that the phase subsolidus demarcations was performed by the SnAs–SiAs2, SnAs–SiAs, Sn4As3–SiAs, and Sn4As3–Si sections. As a result of the experiment, taking into account the theoretical analysis, we suggested a scheme of phase equilibria in the system that involved the implementation of eutectic and four peritectic invariant equilibria, and we used differential thermal analysis to determine the temperature of these four-phase transformations. It was found that extended solid solutions were not formed in the system, and only a substitutional solid solution at least 3 mol % wide was formed based along the SnAs–SiAs2 section based on tin monoarsenide

Identification of Substitutional Solid Solutions Derived from Molybdenum–Vanadium Oxides Using Infrared Spectroscopy

Identification of Substitutional Solid Solutions Derived from Molybdenum–Vanadium Oxides Using Infrared Spectroscopy

X-Ray Diffraction in Mineralogical Research

A brief account of role of X-ray diffraction (XRD) in mineralogical research with special reference to radioactive and atomic minerals is given. Aspects of research methodology such as sample preparation, analysis time, limitations, search match methods for identification, and complimentary techniques are also given. The most common applications of XRD in mineralogical researches related to radioactive/atomic minerals include identification of primary and secondary uranium and associated ore and gangue minerals, determination of the oxidation grade of uraninites, identification of Th, Nb, Ta, Sn, Be, Li, Zr, Hf, Ti, rare-earth elements (REE) minerals, investigations on degree of structural disordering in Nb-Ta minerals, X-ray crystallographic and substitutional solid solution studies, clay minerals, triclinicity of K-feldspar, metamict minerals and influence of the degree of metamictisation on uranium beneficiation, characterisation of leached residue, beneficiated, heat-treated products, metallurgical slags and other mineralogical studies. The results of mineralogical research are used for elucidating physicochemical conditions and geologic processes that prevailed during mineral formation

X-Ray Diffraction in Mineralogical Research

A brief account of role of X-ray diffraction (XRD) in mineralogical research with special reference to radioactive and atomic minerals is given. Aspects of research methodology such as sample preparation, analysis time, limitations, search match methods for identification, and complimentary techniques are also given. The most common applications of XRD in mineralogical researches related to radioactive/atomic minerals include identification of primary and secondary uranium and associated ore and gangue minerals, determination of the oxidation grade of uraninites, identification of Th, Nb, Ta, Sn, Be, Li, Zr, Hf, Ti, rare-earth elements (REE) minerals, investigations on degree of structural disordering in Nb-Ta minerals, X-ray crystallographic and substitutional solid solution studies, clay minerals, triclinicity of K-feldspar, metamict minerals and influence of the degree of metamictisation on uranium beneficiation, characterisation of leached residue, beneficiated, heat-treated products, metallurgical slags and other mineralogical studies. The results of mineralogical research are used for elucidating physicochemical conditions and geologic processes that prevailed during mineral formation

Effects of niobium doping on perovskite La0.5Sr0.5Fe1−xNbxO3−δ structure

Perovskites based on lanthanum-strontium ferrite are considered promising electrode materials for use in various types of fuel cells. The strategy of modifying these materials by partial substitution of iron with highly charged ferroactive cations has proven to be an effective way to enhance their chemical stability. It was shown here that La0.5Sr0.5Fe1−xNbxO3−δ forms a continuous series of substitutional solid solutions up to niobium concentration x = 0.1. It was found for the first time that a further increase in the niobium concentration leads to a transformation of initial rhombohedral (hexagonal) perovskite structure (R3‾c) to less symmetrical structure of orthorhombic perovskite (Pbnm). The latter also forms a number of substitutional solid solutions in the range 0.1 < x ≤ 0.25. High-temperature diffraction analyses of perovskites of composition La0.5Sr0.5Fe1−xNbxO3−δ (x = 0.03, 0.05, 0.1) were carried out in the air atmosphere and in vacuum. It was demonstrated that with an increase in the Nb content in the perovskite, the temperature of the “hexagonal-cubic” phase transition goes up, which indicates an increase in the structural stability of the oxide in the range of operating temperatures of SOFCs/SOECs.

High energy storage performance in Sr0.64Bi0.18Na0.18TiO3-ZnO hybrid solid solution ceramics

Ceramic-based capacitors with excellent recoverable energy storage density (Wrec) and efficiency (η) are greatly desired for pulsed capacitors but challenge as well. In this work, the high energy storage performance with an Wrec of 5.1 J/cm3, an η of 93.4%, and an ultrafast discharge–charge speed t0.9 of 72 ns is achieved in unusual interstitial and substitutional hybrid solid solution of Sr0.64Bi0.18Na0.18TiO3-ZnO (SBNT-Zn), in which two Zn2+ ions occupy one A-site, while one Zn2+ ion occupies one B-site of ABO3 perovskite lattice simultaneously. The addition of Zn2+ increases lattice distortion and breaks long-range ferroelectric order, resulting in more highly dynamic polar nanoregions, higher relaxation behaviors as well as larger polarization (ΔP). Moreover, the extraordinary hybrid solid solution configuration enhances the bandgap of SBNT-Zn and ZnO as a sintering aid refines grain size, both help to enhance electric breakdown strength. This work affirms the feasibility and reliability of forming a hybrid solid solution to develop high-performance ferroelectric materials.

The influence of lattice misfit on screw and edge dislocation-controlled solid solution strengthening in Mo-Ti alloys

Mo-Ti alloys form solid solutions over a wide range of compositions, with lattice misfit parameters increasing significantly with titanium content. This indicates a strong increase in the critical stress for edge dislocation motion. Here, we probe the transition from screw to edge dislocation-dominated strengthening in Mo-Ti solid solutions with titanium content up to 80 at%. The alloys were scale-bridging characterized to isolate the impact of substitutional solid solution strengthening. Mechanical testing yielded no significant influence of grain boundaries or grain orientation. The results were corrected for the strengthening by unavoidable interstitial oxygen. Modelling of screw and edge dislocation-controlled solid solution strengthening was applied to the results to evaluate the contributions of both dislocation types. The analysis reveals that screw dislocation motion controls the strength in allows with less than 40 at% titanium, while edge dislocation motion provides comparable strength for 60–80 at% titanium. These results in a system of reduced chemical complexity support the recent investigations of edge dislocation-controlled strengthening found in high-entropy alloys.

Experimental investigation and thermodynamic optimization of the Co–Ta–Zr system

This work is focused on a deeper understanding of the solidification microstructure of the as-cast alloys, as well as the phase constituents and phase fractions of annealed samples in the Co–Ta–Zr system. Nine primary solidification regions were experimentally determined in the liquidus surface projection, and three primary solidification regions were deduced based on binary phase diagrams. Six three-phase equilibria were observed in the isothermal sections at 1373 and 1273 K. The maximum solubilities of Zr in μ and CoTa2 were determined to be ∼ 6.1 and ∼ 6.7 at% at 1373 K, and ∼ 3.9 and ∼ 5.9 at% at 1273 K, respectively. The maximum solubilities of Ta in Co23Zr6 and CoZr were determined to be ∼ 3.3 and ∼ 14.1 at% at 1373 K, and in Co23Zr6, CoZr and CoZr2 were determined to be ∼ 2.6, ∼ 13.5 and ∼ 11.9 at% at 1273 K, respectively. The Co–Ta–Zr system was optimized by CALculation of PHAse Diagram (CALPHAD) method based on the experimental data. Four solution phases, liquid, bcc, fcc, and hcp, were described as substitutional solution. The thermodynamic models of intermetallic phases Co11Zr2, Co23Zr6, CoZr2, Co3Ta, CoTa2, λ1, λ2 and λ3 were treated as (Co)11(Ta,Zr)2, (Co)23(Ta,Zr)6, (Co,Zr)(Ta,Zr)2, Co3(Co,Ta), (Co,Ta,Zr)(Co,Ta,Zr)2, (Co,Ta)2(Co,Ta), (Co,Ta,Zr)2(Co,Ta,Zr) and (Co,Ta)2(Co,Ta) using a two-sublattice model, respectively. CoZr3 was described as (Co,Zr)(Co,Zr)Zr2 by a three-sublattice model. μ phase was modeled as (Co,Ta,Zr)1(Ta,Zr)4(Co,Ta,Zr)2(Co,Ta,Zr)6 using a four-sublattice model. And CoZr with a B2 structure was described as an ordered phase of bcc_A2, and the model was treated as (Co,Ta,Zr,Va)0.5(Co,Ta,Zr,Va)0.5(Va)3. A set of self-consistent thermodynamic parameters of the Co–Ta–Zr system was obtained using CALPHAD method. The calculated solidification paths and phase fractions can provide theoretical guidance for material design and thermal processing.