Phase Inclusions Research Articles

Compact A15 Frank-Kasper nano-phases at the origin of dislocation loops in face-centred cubic metals

It is generally considered that the elementary building blocks of defects in face-centred cubic (fcc) metals, e.g., interstitial dumbbells, coalesce directly into ever larger 2D dislocation loops, implying a continuous coarsening process. Here, we reveal that, prior to the formation of dislocation loops, interstitial atoms in fcc metals cluster into compact 3D inclusions of A15 Frank-Kasper phase. After reaching the critical size, A15 nano-phase inclusions act as a source of prismatic or faulted dislocation loops, dependent on the energy landscape of the host material. Using cutting-edge atomistic simulations we demonstrate this scenario in Al, Cu, and Ni. Our results explain the enigmatic 3D cluster structures observed in experiments combining diffuse X-ray scattering and resistivity recovery. Formation of compact nano-phase inclusions in fcc structure, along with previous observations in bcc structure, suggests that the fundamental mechanisms of interstitial defect formation are more complex than historically assumed and require a general revision. Interstitial-mediated formation of compact 3D precipitates can be a generic phenomenon, which should be further explored in systems with different crystallographic lattices.

Magma Composition and Formation Conditions of Alkaline-Salic Rocks of the Early Mesozoic Adaatsag Bimodal Association of the Kharkhorin Rift Zone, Central Asia: Data from the Study of Melt Inclusions in Minerals

The composition and formation conditions of magmas of comendites of the Early Mesozoic Adaatsag volcanic association are determined using electron and ion microprobe analysis of melt inclusions, and mechanisms favorable for the accumulation of trace and rare earth elements are identified. The melt and fluid inclusions are found in quartz of comendites sampled in various parts of the section of a volcanic sequence. The melt inclusions consist of glass, a gas bubble, and daughter minerals (fluorite, polylithionite, and K-feldspar). The composition of a gas phase in melt inclusions was studied using Raman spectroscopy. The dominant gas phase components include water and hydrogen. The fluid inclusions are aqueous fluids probably corresponding to KF. The thermometric studies of melt inclusions and the analysis of glasses of homogenized melt inclusions in quartz phenocrysts of comendites showed that magmas crystallized from water-saturated rare metal melts with high Li, Zr, F, Rb, Nb, Y, and Th contents at a temperature of 880–930°C and a pressure of 1000 bar at a depth of ~3.5 km accompanied by degassing. The comparison of our data of the study of melt inclusions in phenocrysts of alkaline salic rocks of the coeval Adaatsag, Dzarta-Khuduk, and Sant volcanic associations, which occur within the Kharkhorin Rift Zone, revealed common principles of magma evolution. This allowed us to propose a similar mechanism of their formation, involving the accumulation of many rare and rare-earth elements, as well as volatile components (F, H2O) in the process of crystallization differentiation. Subsequently, a salt melt rich in Li, F and water could be separated from such comendite magmas. The detection of fluoride aqueous inclusions in quartz allows us to suppose the further evolution of the salt melt leading to the appearance of a concentrated aqueous fluid and the possible participation of the latter in metasomatic processes.

Formation mechanism of (Mn,Cr)Te inclusion in Fe-13Cr stainless steel and its doped atomic structure

ABSTRACT In this study, the formation mechanism of telluride inclusion in Te-containing Fe-13Cr stainless steel was discussed via equilibrium phase diagram calculation, nucleation kinetics, and inclusion characterisation. The first principles method was used to discuss the effects of Fe and Cr atoms on the stability, metallicity, and magnetism of MnTe crystal structure. The observed inclusions are mainly single-particle spherical MnTe and irregular MnTe-MnS composite inclusion (TSCI), Cr can dissolve in MnTe to form (Mn,Cr)Te. The atomic ratio of tellurium to sulphur, Te/S(at.%), in composite inclusions determines the nucleation order of MnTe and MnS in composite inclusions. (Mn0.9375, Cr0.0625) Te is the most likely stable doped crystal structure. Fe can increase the metallicity of MnTe, while Cr atoms reduce the metallicity of MnTe. The solid solution of Fe leads to an increase in ferromagnetism in Mn-Fe-Cr-Te and Mn-Fe-Te systems, while Cr can maintain good ferromagnetism in Mn-Cr-Te systems

Rock physics based velocity-porosity correlations developed for estimation of the elastic properties of the Bakken formations of the Williston Basin, North Dakota

Rock physics models are predictive tools used to estimate the velocity, or elastic properties of formations, based on strong theoretical foundations, as opposed to some of the simple empirical correlations that have been developed for specific regional formations. While the basic rock physics models use simplified assumptions and involve less input, more complex models, such as inclusion-based models, estimate velocity-porosity relation as function of different parameters including pore's fluid saturation and type, cementation, confining pressure and diagenesis. The downside is that these models require performing tedious calculations and in some cases solving complex differential equations. These models may also differ depending on the type of formation, for example, separate models may be used for shales compared to the siliciclastic or carbonate formations.In this paper, we present newly developed correlations that can substitute the rock physics modeling. The developed velocity-porosity correlationsare based on the mineralogical data from the Bakken formation in the Williston Basin, North Dakota, however, they can be used with good accuracy for other formations too. These models were developed based on large volumes of data from simulation of many cases using the differential effective medium (DEM) theory, a commonly used rock physics model. DEM models were developed for composite rock, but assuming single mineral type constituting the rock. The inclusion phase was incrementally added to the matrix phase. The pores were then modeled with three phase fluid (water, oil, and gas) at different saturation levels and finally, different pore's aspects ratios (AR) were assumed to simulate pores heterogeneity (i.e., crack, intraparticle, intergranular and moldic type pore geometries). The correlations constants were extracted for different key minerals in the Bakken, including quartz, calcite, dolomite, anhydrite, illite and kerogen. Having the volume fraction of minerals from lab-based XRD or Elemental Capture Spectroscopy (ECS) logs, linear averaging was applied to estimate the equivalent velocity and elastic properties of the formations.The correlations were applied to several case studies in the Bakken and also compared with the existing lab data, which showed a good agreement with the DEM model. The simplicity of using the correlations consists of simply entering the input values in an excel template that accounts for the constant parameters, using a single approach for different type of formations. This offers a great advantage for their applications. The workflow of developing the correlations and its applications in one case stduy using data from a Well in the Mountrail County will be presented.

Low temperature (<700 °C) SiO2 and Si-rich SiO2 films: Short review

SiO2 layers deposited at temperatures (lower than 700 °C) have attracted a great deal of attention for a large variety of applications, since they can be used for dielectric isolation, a needed approach for multilayer, multifunctional coatings that exhibit two or more properties simultaneously. A similar phenomenon occurred with Si-rich SiO2, a two-phase material in which excess silicon, introduced during the deposition process of the films, forms a Si inclusion phase uniformly embedded in a SiO2 matrix, modifying its optical and electrical characteristics. In this short review, the synthesis methods to obtain high electronic quality SiO2 deposited films at low temperatures, as well as Si-rich SiO2 films (mainly the chemical vapor deposition technique in different versions), precursor materials, and characteristic properties, will be described together with some of their applications, beyond integrated circuit technology, that have become relevant in recent times. This is the case of solar filters, antireflecting coatings for solar cell panels, light emitting devices or liquid crystal displays, and bioimaging and theranostic applications.

TRENDS AND OUTCOMES IN FLIPPED LEARNING-BASED INSTRUCTION IN TEACHING READING: SYSTEMATIC LITERATURE REVIEW

Despite the flipped learning growing popularity, empirical research to increase students' reading abilities is still lacking. The majority of research concentrates on students' impressions of the English language rather than particular language abilities. If there is, speaking, listening, and writing is dominant. This systematic literature review summarizes study findings on trends and outcomes of flipped learning-based instruction in teaching reading. The identification, screening, feasibility, and inclusion phase found thirty-one articles between 2015 and 2022 from the Scopus database with a premium Scopus account to access all sources without limits. The results showed that the research trend of flipped learning in teaching reading was less attractive to researchers than other English skills. It can be seen from the lack of publications from year to year and even tends to decline until May 2022. Further research on flipped learning in teaching reading can enrich the literature on knowledge. In addition, Flipped Learning has positive outcomes in influencing students' performance, especially if combined with other methods. For future research, several different research scopes can be considered, such as creating models or designs to apply flipped learning to students' reading performance and comprehension.

СИНТЕЗ И ЛЮМИНЕСЦЕНТНЫЕ СВОЙСТВА КУБИЧЕСКОЙ КЕРАМИКИ ZrO2-Y2O3-Eu2O3 И HfO2-Y2O3-Eu2O3

In this work samples of ZrO2-Y2O3-Eu2O3 and HfO2-Y2O3-Eu2O3. ceramics are synthesized. Cathodoluminescent studies were carried out. It is shown that, under the chosen synthesis regimes, the ZrO2-Y2O3-Eu2O3 ceramic is stabilized in the cubic phase and is single-phase. The HfO2-Y2O3-Eu2O3ceramic is also stabilized in the cubic phase with small amount of inclusions of the tetragonal phase. Also, in the HfO2-Y2O3-Eu2O3 sample, an inhomogeneous distribution of point defects associated with oxygen deficiency is observed.

Nonlinear micromechanical modeling of fully coupled piezo-elastic composite under large deformation and high electric field

This paper presents mathematical modeling and predictions of effective nonlinear electro-mechanical behavior of piezoelectric materials under large deformation and high electric field. The heterogeneous inclusion problem is extended to investigate the fields dependent electro-elastic behaviors under high fields. The associated strain field dependent Green tensors are introduced. The field dependent interaction tensors, related to Eshelby’s tensors, are explicitly formulated and used to derive micromechanical models based on the Mori–Tanaka approach and the self-consistent model. Due to electric-strain field dependence nonlinear algebraic tensors equations are resulted. Iterative incremental schemes based on the Newton–Raphson algorithm are elaborated and explicit semi-analytical formulations of electric-strain field dependent effective electro-elastic moduli of piezoelectric multi-phase composites are obtained for various inclusion types. Strain and electric field’s effects on effective properties can be analyzed for various electro-elastic composites. Numerical results of field dependent effective electro-mechanical properties are given for several inclusion’s volume fraction and shapes as well as types of matrix and inclusions phases.

The study of homogeneity of the hexagonal Ti3AlC2 phase with inclusions of the titanium carbide

Maps of spatial distributions of Ti, Al, and C on two surfaces of the Ti3AlC2 hexagonal phase (the so-called MAX phase) with inclusions of the TiC phase and Al2O3 were obtained by means of the energy-dispersive X-ray spectroscopy. Volume fractions of phases were 0.848, 0.107, and 0.045, respectively. The sample was cut from the synthesized tablet. One of the analyzed surfaces of the sample was the free outer surface of the tablet (surface 1), and another surface was the cut (surface 2). Histograms of the concentration distributions of elements were plotted. For both surfaces, histograms of all elements have Gaussian forms with mean values of about their stoichiometric concentrations in Ti3AlC2 and TiC phases. Histograms for the carbon have maxima at 34–36 at. %, which is close to the stoichiometric content of the carbon in the Ti3AlC2 MAX phase (33 at. %), and at about 50 at. % that corresponds to the stoichiometric concentration of the carbon in the TiC phase. However, Gaussian standard deviations from these mean values are large (up to 7 at. %), which proves the existence of th vacancies and interstitials of the carbon in phases. The histogram for the aluminum on surface 1 has an additional distribution near zero value of the concentration, and the histogram for carbon on surface 2 has an additional distribution near 27.7 at. %. Both found particularities can be explained by supposing that the outer surface of the original tablet cools down more rapidly than its inner parts.

The Effect of Thermodeformation Treatment on the Structure and Strengthening of the Al–7.1% Zn–2.8% Mg–1.4% Ni–1.1% Fe Alloy Produced via Casting in an Electromagnetic Crystallizer

A calculation technique (Thermo-Calc software code) and experimental methods (scanning and transmission electron microscopy and X-ray spectral analysis) have been used to study the effect of thermodeformation treatment on the structure and strengthening of the Al–7.1% Zn–2.8% Mg–1.4% Ni–1.1% Fe alloy produced via casting in an electromagnetic crystallizer (EMC). It has been shown that at a cooling rate higher than 103 K/s, the entire amount of iron, which exceeds its content in the grade AZ6NF alloy (GOST 4784–2019) by two times, is bound into eutectic inclusions of the Al9FeNi phase of a submicron size. Thecombination of high hardness (more than 190 HV) and ductility indicates the advantages of applying the EMC technology to this alloy.

Exploring the Relationship of Microstructure and Conductivity in Metal Halide Perovskites via Active Learning-Driven Automated Scanning Probe Microscopy.

Electronic transport and hysteresis in metal halide perovskites (MHPs) are key to the applications in photovoltaics, light emitting devices, and light and chemical sensors. These phenomena are strongly affected by the materials microstructure including grain boundaries, ferroic domain walls, and secondary phase inclusions. Here, we demonstrate an active machine learning framework for "driving" an automated scanning probe microscope (SPM) to discover the microstructures responsible for specific aspects of transport behavior in MHPs. In our setup, the microscope can discover the microstructural elements that maximize the onset of conduction, hysteresis, or any other characteristic that can be derived from a set of current-voltage spectra. This approach opens new opportunities for exploring the origins of materials functionality in complex materials by SPM and can be integrated with other characterization techniques either before (prior knowledge) or after (identification of locations of interest for detail studies) functional probing.

Thermal and electrical properties of nanocrystalline superionic NaxCu1.75S (x=0.1, 0.15, 0.2, 25) compounds

The paper presents the results of the studies of thermal properties of nanocrystalline superionic Na x Cu 1.75 S (x = 0.1, 0.15, 0.2, 25) compositions, and preliminary results of Na 0.1 Cu 1.75 S using as energy stored cathode material in Na-ion half-cell with NaPF 6 electrolyte and Na anode. The compositions contain a few copper sulfide phases: monoclinic chalcocite Cu 2 S, orthorhombic anilite Cu 1.75 S, triclinic roxbyite Cu 1.74÷1.82 S, also the compositions can contain monoclinic Na 2 Cu 4 S 3 , orthorhombic Na 2 S, cubic Cu 2 O as inclusion phases. The sizes of powder particles lie in the range from 10 to 113 nm. Differential scanning calorimetry revealed in Na 0.1 Cu 1.75 S the endothermic thermal effects with critical temperatures near 123 o C, 422 o C and 442 o C, caused by structural transitions in copper sulfide. Fourth endothermic peak at 323 o C presumably belongs to Na 2 S phase. The minimum for the Fermi level at about 420°C is found with using of the e.m.f. E of the electrochemical cell of the Cu/CuBr/Na 0.10 Cu 1.75 S/Pt, which corresponds to minimum for the carrier concentration. This conclusion correlates well with the observed conductivity minimum at about 410°C. Electrode material Na 0.10 Cu 1.75 S achieved a significant specific energy density 146.5 mAh/g in half-cell assembled from the cathode active material, electrolyte (NaPF 6 in 0.5 mol PC) and Na anode.

Models for effective elastic constants of irradiated U-10Mo fuels with distributed fission gas bubbles

The multi-scale related models for the effective elastic constants of porous U-10Mo fuels under the irradiation conditions are developed with the proposed multi-level homogenization method. The grain recrystallization effects are taken into account, with fission gas bubbles (FGBs) distributed in the external bubble-contained region of Representative Volume Element (RVE). Performing theoretical analysis and numerical simulation, the effective elastic performances are firstly obtained for the bubble-contained region, and then are volumetrically averaged with those of the internal no-bubble region. The effective elastic constants of irradiated U-10Mo fuels determined in this study agree well with some available experimental data in the references. The research results indicate that: (1) the effective elastic constants of porous U-10Mo fuels are hardly affected by the pore pressure, mainly depending on the macroscopically average porosity; (2) the theoretically derived model for the effective bulk modulus is the same as the degraded Mori-Tanaka model, with the inclusion phase there regarded as bubbles having zero elastic constants. The developed models correlate the elastic constants of irradiated U-10Mo fuels with their continuously varying porous structures, which lay a foundation for modeling the multi-scale irradiation-induced thermo-mechanical coupling behaviors.

Average Eshelby tensor of an arbitrarily shaped inclusion from convexity to non-convexity: Effective elastic properties of composites

The effective mechanical properties of composites are strongly influenced by the morphology, volume fraction, and properties of the inclusion phase. Extensive theoretical models for the evaluation of effective properties are mainly based on the continuum micromechanics derived from the well-known Eshelby’s solution of an ellipsoidal inclusion problem, which are subjected to the limitations on the Eshelby tensor for a non-ellipsoidal inclusion. This work devises a three-step method to derive the average Eshelby tensor of an arbitrarily shaped inclusion from convexity to non-convexity in an elastic field. The proposed three-step method is user-friendly and avoids the singularity that arises from solving the complicated integrals for an arbitrarily shaped inclusion. The calculated average Eshelby tensors of inclusions with different morphologies, including Platonic solids, superballs, superellipsoids, doughnuts, helices, and non-convex particles, are thereafter compared against the existing data reported in the literature, in order to verify the reliability of the present method. Moreover, we also incorporate the proposed method into a micromechanical model to predict the effective elastic moduli of two-phase composites, in which congruent non-ellipsoidal inclusions of a specific volume fraction are randomly distributed in a homogeneous matrix. Comparisons with the direct finite element method (FEM) simulations indicate that the developed micromechanical model is a reliable means to evaluate the elastic properties of composites. The proposed average Eshelby tensor of an arbitrarily shaped inclusion can also be generalized to the theoretical predictions of the effective transport properties of composites with inclusions of diverse types and shapes, such as particles, rocks, granules, pores, fibers, and cracks.

Development of the teacher’s technological pedagogical content knowledge (TPACK) from the Lesson Study: A systematic review

A systematic review is presented with the purpose of exploring the trends associated with the development of technological pedagogical content knowledge (TPACK) from Lesson Study. In the 21st century, technology established a complex and necessary relationship with different sectors of society, enabling different conceptual and practical models for the incorporation of technologies in teaching. TPACK was one of the most outstanding. In this perspective, a systematic literature review is presented taking into account 16 studies published between 2015 and 2021 with the purpose of analyzing the development of TPACK in teachers, in research that uses the Lesson Study (LS) as an intervention strategy. The review was carried out in April 2022 using the following databases: Scopus, Web of Science, Spinger Link, Proquest Central, Science Direct, Redalyc, Dialnet and Scielo. The phases of identification, screening, selection and inclusion of the flowchart of the PRISMA guide were applied. The results reveal that the LS constitutes a theoretical and practical framework that provides contextualized opportunities to work on the training needs and interests of teachers, promoting self-assessment and the construction of new conceptions about teaching with technologies. Therefore, the theoretical discussion reveals that the integrative vision of TPACK is the perspective that predominates the development of this type of research.

Investigation of phase separation as a source of optical losses in IR glasses for fiber optics

Extremely tough requirements for the optical transparency of IR glasses for fiber optics determine the specifics of the study of phase separation in such materials. Theoretical approaches and experimental techniques of such research are proposed. The permissible contents of phase inclusions in IR glasses for active and passive fiber optics are estimated. The priority field of their control is identified and highly sensitive methods for its implementation are selected. Their effectiveness in choosing the most resistant to crystallization and liquation glasses for fiber optics is demonstrated by the example of GeSx (1.3 ≤ x ≤ 1.5) glasses. The selection criterion is the scattering losses caused by phase separation. For the first time, micro-liquation has been revealed in the studied compositions. Based on data on the sizes, contents, and refractive indices of phase inclusions, scattering losses in glasses obtained under various quenching conditions are estimated. The most promising glass compositions for fiber applications are established.

Analysis of Lead Smelting Technology in the Early Bronze Age Based on Smelting Slag from the Central Plains of China

To explore the source of Pb in Bronze Age artefacts from the Central Plains (Zhongyuan) in China, we investigated non-ferrous minerals from the Qingyuan archaeological site in Yuanqu County near the Zhongtiao Mountains. Fragments of smelting slag from the Erlitou cultural layer were collected. The smelting slag was investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and lead isotope analysis. The SEM and EDS results confirmed that the slag contained Pb, Pb–As, and Cu–Pb–Sn inclusions and non-metal impurities such as low-Zn spinels. The XRD results signified that the bulk of the slag comprised Fe–Mn–Si phases. The chemical state of Pb was mainly Pb–O with some metallic Pb, as identified by XPS. The theoretical melting point was calculated using FactSage7.1 based on the composition and phase characterisation. The calculated temperature was 1100–1200 °C, which agreed well with the actual melting point of 1114–1354 °C. The slag composition and inclusion phases indicated that Pb–Zn–O ores with Mn and As were added during reduction smelting in Qingyuan. The raw materials of smelting included crude Pb with minor amounts of Cu, As, and Sn. Lead isotope analysis revealed that the lead materials produced in Qingyuan were likely transferred to Yanshi City in the Shang Dynasty. The findings of this study provide significant clues for exploring lead mineral production in the Central Plains during the Early Bronze Age.

MAGMA COMPOSITION AND FORMATION CONDITIONS OF ALKALI-SALIC ROCKS OF THE EARLY MESOZOIC ADAATSAG BIMODAL ASSOCIATION OF THE KHARKHORIN RIFT ZONE OF CENTRAL ASIA (DATA FROM THE STUDY OF MELT INCLUSIONS IN MINERALS)

Based on the method of investigation of melt inclusions using electron and ion microprobe, the magma composition and formation conditions of comendites of the Early Mesozoic Adaatsag volcanic association (Mongolia) were studied. The mechanisms leading to the accumulation of rare and rare earth elements in them were determined. Melt and fluid inclusions are found in quartz from the comendites, collected from different parts of the volcanic sequence. The melt inclusions consist of glass, a gas bubble and daughter minerals represented by fluorite, polylithionite and potassium feldspar. The use of the Raman spectroscopy method made it possible to study the composition of the gas phase in melt inclusions. It is determined that the predominant components of the gas phase are water and hydrogen. Fluid inclusions are represented by aqueous solutions that correspond to KF in composition. The concentration of KF in the solution reach up to 4.0–4.1 wt. %. Thermometric experiments with melt inclusions and analysis of the composition of glasses of homogenized melt inclusions in quartz of the comendites showed that the crystallization of magmas of these rocks occurred from water-saturated rare-metal melts with high contents of Li, Zr, F, Rb, Nb, Y and Th at temperatures of 880–930°C and at a pressure of 1000 bar at a depth of ~3.5 km and was accompanied by degassing processes. Comparison of the obtained data on the study of melt inclusions in the phenocrysts of the alkali-salic rocks of the same age volcanic associations Adaatsag, Dzarta-Кhuduk and Sant, developed within the Kharkhorin rift zone, revealed general patterns of their magma evolution. This allowed us to propose a similar mechanism of their formation, involving the accumulation of many rare and rare-earth elements, as well as volatile components (F, H2O) in the process of crystallization differentiation. Subsequently, a salt melt rich in Li, F and water could be separated from such comendite magmas. The detection of fluoride aqueous inclusions in quartz allows us to suppose the further evolution of the salt melt leading to the appearance of a concentrated aqueous fluid and the possible participation of the latter in metasomatic processes.

Brain changes in neuroimaging of adult patients with vitamin D deficiency: systematic review protocol

IntroductionBrain abnormalities detected through neuroimaging are described in patients with vitamin D deficiency, however, it is still not clear which cerebral alterations are more frequent and characteristic in this population....

Exploring Justice in the Process of Redesigning Local Development Strategies for LEADER: Representation, Distribution, and Recognition

After its first funding period from 1991 to 1994, LEADER was positively evaluated as a successful strategy to empower actors at the regional level, enable regional development and contribute to territorial cohesion within the European Union. Critical studies, however, have highlighted elitist tendencies in LEADER processes and asked whether the proclaimed goal of strengthening ‘the local’ contributes to new or other forms of social and spatial injustice. Our research focus lies in how representation, distribution, and recognition—as the three interrelated dimensions of justice according to Nancy Fraser—are featured in the discourse related to redesigning a local development strategy (LDS). During this process, which is conceived as the most open and inclusive phase in each LEADER funding period, we conducted expert interviews and participatory observations in a case study region and gathered media reports, documents, and official regulations. In our analysis of issues of representation, distribution, and recognition, we also focus on the spatial scales that are referred to and the ways in which the involved actors challenge and justify the status quo. Our analysis explicates the actors’ implicit normative understandings as well as their different perspectives and positions considering perceived injustice. Even though the LDS process provides opportunities to negotiate these positions and to work towards more just representation, distribution, and recognition, they are partly constrained by structural and individual dependencies.