Formation Of Crystalline Phases Research Articles

Thermal, Surface, and Structure Analysis of Molybdenum substituted Bioactive Glass Ceramics SiO2-CaO- MoO3-P2O5

This study explores the incorporation of molybdenum oxide (MoO3) as a dopant in SiO2-CaO-P2O5 (BGC) glass-ceramics through a meticulously designed sol-gel synthesis process to optimize properties for regenerative medicine applications. Comprehensive characterization techniques, including thermal analysis (TGA/DSC), Raman spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR), elucidate the morphological and structural modifications induced by MoO3 doping. Results reveal that MoO3 affects the glass transition temperature, crystallization behavior, and surface morphology, leading to enhanced glass stability, crystallinity, and surface properties. The mechanical properties, such as fracture toughness, also significantly improved with MoO3 doping due to the formation of crystalline phases and densification of the material structure. Notably, the doping of MoO3 promotes the formation of CaMoO4 crystalline phases and influences the synthesis of hydroxyapatite—critical for bone tissue regeneration—when immersed in simulated body fluid (SBF). The study highlights the hydrophilic nature of the doped samples, facilitating bone development and cell adhesion, while also showing that increased MoO3 content reduces the rate of hydroxyapatite formation and material degradability. These findings demonstrate that MoO3 doping via the sol-gel method offers a promising approach for tailoring BGC glass-ceramics' properties, making them more suitable for regenerative medicine applications. This research underscores the potential of MoO3 in advancing biomaterial development for tissue engineering and implantology.

High Specific Surface Area TiO2 Aerogels Incorporated in situ with Co/Mn Oxides as Stable Electrochemical Capacitor Electrodes

Nanocomposite aerogels comprised of TiO2 and metal (Co and Mn) oxides are synthesized via an in situ sol–gel method in this study, and their structural, compositional and electrochemical properties are evaluated for possible applications as electrodes in energy storage devices. The inclusion of metallic oxides into TiO2 aerogels hinder the formation of titania crystalline phases, preserved particle sizes close to their original dimensions and yielded higher specific surface areas compared to pure TiO2 aerogels after heat treatment. High specific surface areas in aerogels positively affect the electrochemical properties, allowing a high electrochemical activity of the electrodes, in addition to intensifying the transport of ions and solvents through the mesoporous network of this material. Evaluation of the electrochemical properties of the aerogel‐based nanocomposites involves galvanostatic charge–discharge, cyclic voltammetry, and impedance spectroscopy. The nanocomposites exhibit enhanced electrochemical properties and stable performance within the range suitable for supercapacitor applications, as indicated by the Ragone chart. Notably, aerogels with higher incorporation of cobalt and manganese oxides in TiO2 aerogels exhibit significantly elevated specific surface areas, reaching 562 and 555 m2 g−1, respectively. These values are notably high for nanocomposites, underscoring the potential of these electroactive materials for electrochemical capacitors.

Mechanically Alloyed FeNi and Fe Powders Crystalline Size, Phase Formation, and Morphology: Investigation on Milling Time Impact

Mechanically Alloyed FeNi and Fe Powders Crystalline Size, Phase Formation, and Morphology: Investigation on Milling Time Impact

Mechanically Alloyed FeNi and Fe Powders Crystalline Size, Phase Formation, and Morphology: Investigation on Milling Time Impact

Mechanically Alloyed FeNi and Fe Powders Crystalline Size, Phase Formation, and Morphology: Investigation on Milling Time Impact

Tailoring the crystalline and amorphous phase ratios of TiO2 through the use of organic additives during hydrothermal synthesis

The photocatalytic properties of TiO2 are primarily determined by its crystallinity and crystalline phase ratios. To improve the photocatalytic properties of TiO2, greater control over the formation of crystalline and amorphous phases during synthesis is therefore required. In this study, we demonstrate how the addition of minute amounts of three organic compounds (isopropanol, acetone and acetic acid) during hydrothermal treatment affects the amorphous and crystalline phase ratios: the addition of isopropanol or acetone accelerates the phase transition from anatase and brookite to rutile, whereas the addition of acetic acid inhibits the transformation of anatase to rutile, increasing the content of amorphous phase compared to samples where no organic compound was added. We show that the combination of the organic compound added, along with the duration of the hydrothermal treatment, can be used to tailor the phase composition of TiO2, so as to obtain either: i) TiO2 with a high content of both rutile and amorphous phase, ii) TiO2 with a high rutile content and iii) TiO2 with different ratios of all four phases, when the duration of synthesis is short (2–4 h). The materials synthesized exhibited high photocatalytic activity (in most cases higher than P25), which is attributed to the beneficial phase composition and high specific surface area.

Fe-rich X-ray amorphous material records past climate and persistence of water on Mars

X-ray amorphous material comprises 15-73 wt.% of sedimentary rocks and eolian sediments in Gale crater. This material is variably siliceous and iron rich but aluminum poor. The presence of volatiles is consistent with the existence of incipient weathering products. To better understand the implications of this material for past aqueous conditions on Mars, here we investigate X-ray amorphous material formation and longevity within terrestrial iron rich soils with varying ages and environmental conditions using bulk and selective dissolution methods, X-ray diffraction, and transmission electron microscopy. Results indicate that in situ aqueous alteration is required to concentrate iron into clay-size fraction material. Cooler climates promote the formation and persistence of X-ray amorphous material whereas warmer climates promote the formation of crystalline secondary phases. Iron rich X-ray amorphous material formation and persistence on Mars are therefore consistent with past cool and relatively wet environments followed by long-term cold and dry conditions.

Performance improvement of glass-based lightweight aggregates through thermodynamic modelling design and lightweight mortar validation

To reduce environmental impact of sintered lightweight aggregates (LWAs), in this study, novel glass-based LWAs were produced from municipal solid wastes at 900 °C. The mix was designed by thermodynamic modelling to optimize the phase composition, liquid phase properties, and microstructure of the LWAs. Results demonstrated that the inclusion of incinerated sewage sludge ash (ISSA) increased the viscosity of the liquid phase, resulting in a refined pore structure characterized by smaller, more isolated pores, and thicker pore walls. Additionally, ISSA facilitated the formation of various crystalline phases (e.g. wollastonite) to stabilize the pore structure, thereby enhancing densification and matrix strength. Leaching behaviour tests confirmed the suitability of glass-based LWAs for environmentally safe lightweight products. Lightweight mortars incorporating developed LWAs exhibited a high 28-day compressive strength (up to 57.9 MPa) with a low density of 1688 kg/m3 and a low thermal conductivity of 1.0 W/(m·K). The energy simulation revealed substantial reductions in energy consumption when the lightweight mortars were utilized in the building compared with the reference building using normal-weight C30 concrete, underscoring its promising role in conserving energy and reducing carbon emissions.

Glass and nanocrystalline phase formation in CuZrAg alloys: Insights from combinatorial thin film libraries studied by mapping synchrotron X-ray diffraction

We report detailed diffraction peak analysis and parameters indicative of the transition between fully amorphous microstructures and nanocrystal formation in sputter deposited thin film metallic glasses. Specifically, we fabricated ternary CuZrAg alloy films (2µm thickness) with a large compositional gradient on flexible, X-ray transparent polymer substrates in high vacuum conditions. The combinatorial libraries were subjected to point-by-point structural (XRD synchrotron radiation) and chemical (X-ray fluorescence spectroscopy) analysis, characterizing roughly 172 alloys. A strong correlation was found between peak symmetry and width, and early stages of crystalline phase formation. These nanocrystals are difficult to detect from the evolution of the peak position. In view of current literature, our data questions the recently claimed universality of the peak width as indicator of high glass forming ability. The addition of Ag significantly improves the poor glass formation of binary CuZr (36 alloys) under identical deposition conditions, as fully amorphous alloys are found for the majority of the investigated composition space. A thorough understanding of the microstructure of CuZrAg alloys on flexible substrates is highly relevant in view of favourable antibacterial properties and potential application as coatings for biomedical surfaces.

OBTAINING COPPER SELENIDE NANOWIRES IN SiO<sub>2</sub>/Si TRACK TEMPLATES

This paper presents a study of copper selenide nanowires obtained for the first time by template synthesis. This method allows precise control of the size and morphology of nanostructures, which indicates its high efficiency in obtaining homogeneous and well-deposited copper selenide nanowires. The SiO2/Si track template was obtained by irradiation on a DC-60 accelerator (Astana, Kazakhstan), after which the track template was chemically etched to form cylindrical pores. After irradiation and further chemical etching, copper selenide was deposited into the SiO2/Si track template by electrochemical deposition method. The morphology and amount of deposited nanoprecipitates were observed using a QUANTA 200i electron microscope with 3D scanning. X-ray diffractometer was used to determine the crystallographic structure of copper selenide nanoprecipitates. X-ray diffraction analysis (XRD) was carried out on a Rigaku miniflex 600 X-ray diffractometer. The XRD analysis revealed the formation of cubic crystalline phase of copper selenide nanowires electrochemically deposited on SiO2/Si track template. Photoluminescence (PL) spectra were measured on a CM2203 spectrofluorimeter to study the optical properties of the nanowires. The PL spectra were recorded at room temperature from 300 nm to 800 nm in 5 nm steps under a xenon lamp. Differential decomposition of the FL spectra showed two main peaks (2.5 and 2.8 eV).

External magnesium sulfate attack on hydrated Portland-limestone cements: Effect of the concurrent presence of sodium chloride in the corrosive environment and metakaolin admixture in the binder

Magnesium sulfate attack on Portland-limestone cement pastes at low temperature was investigated considering the concurrent presence of sodium chloride in the corrosive solution. The common deterioration mechanism, involving leaching of portlandite and C─(A─)S─H phase and formation of crystalline phases and amorphous cross-linked aluminosilicate structures, was mitigated in the pastes made from ordinary or Portland-limestone cements by increasing amounts of dissolved sodium chloride. Conversely, it was intensified in the blend with metakaolin by the additional decomposition of C─A─H phases with the formation of amorphous aluminate hydrate. The reduced cross-linking of the aluminosilicate structures is attributed to the structural association of sodium in the low-Ca/Si chains. C─A─H phase was also consumed in the heavily deteriorated cement paste with the highest limestone content. The mitigating effect of sodium chloride is proposed to be due to the corrosive environment's reduced acidity and the protective effect exerted by the sodium ions absorbed at the surface of aluminosilicate structures.

Novel titanium-based sulfur-containing BMG for PBF-LB/M

This paper investigates the additive manufacturing route for a novel glass-forming titanium-based sulfur-containing alloy of the composition Ti60Zr15Cu17S8\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{Ti}}_{60} {\ ext{Zr}}_{15} {\ ext{Cu}}_{17} {\ ext{S}}_{8}$$\\end{document}. This system is a promising candidate for medical devices since the lack of toxic components is combined with a high corrosion resistance and strength. Preliminary experiments and simulations show a general processability of bulk material by powder bed fusion technologies. TEM and XRD reveal an amorphous microstructure of laser-treated surfaces. Ultrasonic atomization is used to fabricate a flowable powder feed stock with spherical morphology and crystalline microstructure, which is suitable for processing in powder bed fusion. Correlations between detected crystalline phase formations and melt pool dynamics are revealed by SEM and EDX. It is shown that bulk samples with a high relative density and partially crystalline microstructure can be manufactured.

STUDY OF THE INFLUENCE OF FRIT VISCOSITY ON THE MELTING CHARACTERISTICS OF GLAZES FOR SINGLE-FIRED CERAMIC TILES

The need to expand the assortment of ceramic tiles and ceramic granite by modifying the structure and texture of glass coatings with special properties using the technology of one-time firing, taking into account the aspects of resource and energy saving and environmental friendliness of widely used finishing materials, is analyzed. The need to create new types of ceramic tiles and ceramic granite in domestic production, taking into account the needs of the fuel and energy complex and the domestic raw material base in the event of emergency situations, has been determined. The purpose and tasks of the work are formulated, which determine the need to study the fusible characteristics of glazes and their viscosity for ceramic tiles for one-time firing. The peculiarities of frit compositions are analyzed and the requirements for surface properties are established to ensure a defect-free glaze coating for one-stage firing of ceramic tiles. High-calcium zinc aluminum silicate frits with a short interval of formation of a vitreous coating during single firing with different textures on PJSC «Kharkiv Tile Plant». The change in the characteristics of the change in viscosity and melting point of frit during the formation of glass-crystalline coatings, depending on the chemical composition and phase transformations during heat treatment, was analyzed. It was determined that ensuring crystallization viscosity η = 108,1-8,5 Pa·s in the area of ​​nucleation temperatures 1050-1150 °С for experimental frits indicates intensive formation and growth of crystalline phases and is decisive for ensuring their melting in the range of temperatures 1100 -1200 °С. It was established that the rapid increase in the viscosity of frit determines the rapid change in the characteristic melting curves in a narrow temperature range when ensuring successive stages of softening, forming a sphere, a hemisphere and melting is an indicator of the possibility of using the developed frits by single firing technology. The use of developed frits in single firing technology will significantly increase the competitiveness of domestic ceramic tiles and contribute to the stabilization of the market in the conditions of sustainable development of the country.

Z-Scheme heterojunction Cu2(OH)3F/Bi2WO6 with improved photocatalytic activity for uranium removal from wastewater under air atmosphere

The proper treatment of uranium-contaminated nuclear wastewater is important for uranium resource recovery and environmental protection. Photocatalytic strategies have emerged as promising approaches for improving uranium removal efficiency. In this study, a Z-scheme heterojunction Cu2(OH)3F/Bi2WO6 (CFO/BWO) was synthesized by directly depositing CFO onto a BWO semiconductor for highly efficient photocatalytic removal of uranium from wastewater. The CFO semiconductor contains abundant O–H bonds and a high conduction band position, which can couple with BWO to form a heterojunction via interactions between the O and W atoms. Owing to the high electronegativity of CFO, electrons easily transfer from BWO to CFO, resulting in enhanced electron-hole separation and promoted electron transmission. Importantly, introducing CFO narrowed the bandgap of CFO/BWO compared to that of BWO, providing an appropriate band position, which is more conducive to the photocatalytic immobilization of uranium. Moreover, the mechanism of CFO/BWO heterojunction for photocatalytic immobilization of uranium revealed the formation of a stable crystalline phase of (UO2)O2·2H2O during the photocatalytic process. As a result, CFO/BWO could remove 91 % of uranium from simulated wastewater under an air atmosphere. The findings of this study provide a promising strategy by regulating the band position of heterojunctions for photocatalytic immobilization of uranium.

Molecular synthesis strategies for binary MO2 (M = V, Sn, Ti, Zr, Hf) high-entropy oxides as superior catalysts for enhanced oxygen evolution

Entropy stabilized multi-cation oxides are of significant interest in heterogeneous catalysis due to higher number of active sites, when compared to simple binary oxides, which reduces the overpotential for catalytic transformations. To control the enthalpy of mixing and suppress potential phase segregation, the use of molecular metal alkoxides for chemical cross-linking of different metal centers shows promise in creating homogenous high entropy chemical preceramic networks. Herein, we report on a high-entropy MO2 phase (M = V, Sn, Ti, Zr, Hf), synthesized by cross-linking partially hydrolyzed metal iso-propoxides [M(OH)n(OiPr)4-n]x. The amorphous xerogels calcined at 700 °C, 900 °C and 1250 °C revealed the formation of a single crystalline phase [(V, Sn, Ti, Zr, Hf)O2] that was verified by powder X-ray diffraction analysis, whereas the chemical composition was investigated by X-ray photoelectron spectroscopy and X-ray absorption spectroscopy. The HEO exhibited superior catalytic activity in oxygen evolution reaction with an overpotential of 312.7 mV and an electrochemically active surface area of 0.625 F cm−2. Furthermore, the chronopotentiometry measurements confirmed a high stability (> 90 h) for the HEO samples.

Nanotubes of a Different Kind: Stoichiometry and Geometry of the Orange II/γ-Cyclodextrin Complex in Water.

Orange II (O-II), a water-soluble ionic azo dye, aggregates and eventually forms needle-like crystals at concentrations greater than 0.15 M. However, when equimolar amounts of γ-cyclodextrin (γ-CD) are added to solutions containing O-II at 0.025 M or higher, the solution's appearance rapidly changes presenting a viscous, birefringent liquid, a lyotropic liquid crystalline solution. Birefringence is absent when viewing aqueous solutions of only O-II or γ-CD at concentrations greater than 0.03 M. Using ultraviolet-visible (UV-vis) and fluorescence spectroscopy, coupled with conductivity measurements, we postulate a structure for the basic "building block" of the self-assembly that eventually gives rise to a rodlike superstructure, leading to the formation of a lyotropic liquid crystalline phase.

Building Nitridic Networks with Phosphorus and Germanium-from GeIIP2N4 to GeIVPN3.

Nitridophosphates and nitridogermanates attract high interest in current research due to their structural versatility. Herein, the elastic properties of GeP2N4 were investigated by single-crystal X-ray diffraction (XRD) upon compression to 44.4(1) GPa in a diamond anvil cell. Its isothermal bulk modulus was determined to be 82(6) GPa. At 44.4(1) GPa, laser heating resulted in the formation of multiple crystalline phases, one of which was identified as unprecedented germanium nitridophosphate GePN3. Its structure was elucidated from single-crystal XRD data (C2/c (no. 15), a = 8.666(5), b = 8.076(4), c = 4.691(2) Å, β = 101.00(7)°) and is built up from layers of GeN6 octahedra and PN4 tetrahedra. The GeN6 octahedra form double zigzag chains, while the PN4 tetrahedra are found in single zigzag chains. GePN3 can be recovered to ambient conditions with a unit cell volume increase of about 12%. It combines PV and GeIV in a condensed nitridic network for the first time.

Manufacturing process and annealing influence on the dynamic mechanical properties and physical structure of LLDPE thin films

Thin films of Linear Low-Density Polyethylene are used for stratospheric balloon applications. They undergo tensile mechanical stress on a wide range of temperatures [-95; 55]°C. The aim of this study is to compare the influence of blown film and double-bubble manufacturing processes on the crystalline phase and mechanical properties of the films through their operating temperatures (flight, storage, and transportation temperatures). Dynamic Mechanical Analysis and Differential Scanning Calorimetry have been used to monitor the dynamic mechanical properties in tension mode and the crystalline phase of the films respectively. The films mechanical properties are dependent on their manufacturing process. The double-bubble process allows isotropic tensile mechanical properties regarding stretching direction, whereas the blown film process favors only transversal direction. To simulate different storage conditions, annealing has been performed. The influence of annealing on the tensile mechanical properties of the films depends mainly on the internal stress stored during manufacturing. The double-bubble process produces a biaxially stretched film with a higher stretching ratio than blown films. The dissipated internal stress can be associated with thermal shrinkage and goes up to 10 % for the biaxially stretched film. The more internal stress is stored, the more E′ and E″ increases. Annealing also favors the formation of a secondary crystalline phase that is dependent on annealing temperature and time, and exhibits αc relaxation. After annealing, the amorphous phase is less stretched, and the crystalline phase keeps its orientation.

Solution Processed Hybrid Lead Perovskite Films for White Light Emission and Lasing Applications

Abstract2D organic–inorganic hybrid lead halide perovskite films are fascinating optoelectronic materials for white‐light emission and lasing applications. Here, it is demonstrated that nano‐meter‐thick films of perovskites can be formed at room temperature using Langmuir–Schaefer (LS) deposition technique. In situ X‐ray measurements reveal a self‐assembly process of the 2D perovskite formation at the air–water interface. This formation process requires the presence of stearic acid monolayer on the water subphase having a solution of lead‐perovskite in dimethylformamide. Microscopy and X‐ray measurements of these nanofilms transferred onto substrates show crystalline phase formation that deviates from the known orthorhombic structure of the bulk crystals. The nanofilms exhibit novel broad optical emission with sharp band‐edge transition in temperature‐dependent photoluminescence studies. Also, their band‐edge emission is distinctly blue‐shifted compared to that of thicker 2D perovskite flakes prepared by the slow‐cooling chemical synthesis process. 2D flakes exhibit lasing that cannot be obtained in the LS nanofilms as their thicknesses are lower than the lasing wavelength prohibiting wave‐guide formation. The results show that the 2D single‐crystalline nature of the LS films and flakes are suitable materials to develop broad‐band white light emission across the entire visible range and to obtain lasing without external cavities, respectively.

Chemical looping reforming with water splitting (CLRWS) for syngas and hydrogen coproduction using the ternary metal-oxides (Ca-Fe-Cu–O) as oxygen carriers

In this work, chemical looping reforming with water splitting (CLRWS) using ternary metal oxides (Ca-Fe-Cu–O) as oxygen carrier (OC) was investigated for syngas and hydrogen coproduction. The introduction of Cu into the Ca-Fe-O system results in the formation of the main crystalline phases, which include Ca2Fe2O5, CuFe2O4, and a small amount of CaO. The presence of Cu enhances the oxygen transfer capacity (OTC) and reduces the reduction temperature of Ca-Fe-O oxides. When the ratio of Ca:Cu:Fe equals 0.5:0.5:2, the Ca0.5Cu0.5Fe2O4 exhibited the highest hydrogen yield and purity of 9.15 mmol/(g OC) and 96.80 %, respectively. The syngas yield, purity and fuel conversion were 66.48 mol/L, 74.76 % and 83.12 %, respectively. It can be attributed to the suitable ratio of brownmillerite Ca2Fe2O5 and the spinel CuFe2O4 in Ca0.5Cu0.5Fe2O4. The crystal phases of Ca2Fe2O5 and CuFe2O4 exhibit a synergistic effect in the Ca-Fe-Cu–O system, the formation of CuFe2O4 enhances the lattice oxygen activity, while the brownmillerite-structured Ca2Fe2O5 inhibits the sintering and agglomeration of CuFe2O4 due to the morphology effect. The Ca0.5Cu0.5Fe2O4 showed almost stable reactivity after 10 cycles.

Nanoparticles reinforced ceramic bonds derived from K-gel geopolymers composites at elevated temperature: Pore structure, micro and meso scale properties

The refractory alkaline activated materials gained attention in the various engineering and industrial applications due to its environmental and eco-friendly benefits. The present study deals with the evaluation of the effects of nano-ZrO2, nano-Al2O3, and nano-TiO2 particles reinforcement mechanism on the final properties of the geopolymer matrices subjected to thermal treatment from 900 to 1250°C. Three series of composite matrices were obtained by adding 2–8 wt% of nanoparticles content (Al2O3, TiO2 and ZrO2) within the activated mortar and were devoted RAi, RRi and RZi (i = 2, 3, 5 and 8%).The designed composite matrices were characterized using several analytical methods and techniques including the mechanical characterization, mercury intrusion porosimetry (MIP) as well as the microstructural characterization. The results revealed that the use of the high content of nanoparticles (8 wt%) favored formation of a cross-linkage chain around the crystalline phases present within matrices. Their resulting percolation-induced reinforcement acted as supplementary with the interlocked network from the crystalline phases within the matrices to rendering it denser and compact. The matrices with high content of the nanoparticles added exhibited high mechanical properties at 1250°C. Flexural strength and young modulus were 70.7, 52 and 78.4 MPa, and 28.15, 22.61 and 29.86 GPa for RA, RR and RZ series respectively. Furthermore, the formation of the new crystalline phase like cordierite, mullite and leucite contributed to hindering the crack propagation within the matrices and increased the level of crystallization of the matrices by providing a homogeneous and well-dispersed structure. The produced matrices emerged stable at high temperature treatment and therefore could be used as a potential candidate for the materials for elevated temperatures applications.