Growth Of Crystalline Phase Research Articles

Mono-axial stretching-induced growth of crystalline phase of melt-processed perfluoroalkoxy alkane (PFA) films for protecting inner layer of battery pouch films

Cast polypropylene (CPP) is employed as an inner layer of pouch films; however, CPP shows poor electrolyte, mechanical, and electrical stability, which can lead to instability during cell operation. In this study, we pioneered the use of perfluoroalkoxy alkanes (PFA) in the melt extrusion process to fabricate films based on their high melting flow index, establishing optimal conditions for producing uniform films. We further enhanced the functionality of these films by controlling the crystalline phase orientation through high-temperature uniaxial stretching, which is aimed at applications in battery pouch films. The stretched PFA films exhibited dramatically improved mechanical and insulation properties compared to traditional CPP films, 307.4% increase in tensile strength and 1,748.8% increase in breakdown strength, respectively. Based on these findings, we proposed that stretched PFA films, with their superior performance, are viable substitutes for CPP as the inner layer in battery pouch films. This research not only advances the material science of polymer films but also contributes to the development of safer and more efficient battery technologies.

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.

Advanced structure research methods of amorphous Co69Fe4Cr4Si12B11 microwires with giant magnetoimpedance effect: Part 3 – Cluster growth and crystal nucleation

This Part 3 focuses on the detailed study of the nanostructures forming in amorphous microwires which were previously received and described in the Part 2. The clustering process was studied at long-term DC Joule heating’s much lower the crystallization temperature. Particular attention is paid to the study of the redistribution of the components of the initial stage of crystallization. The studies were carried out using the Atom Probe Tomography method (APT), which allows for the identification of individually considered atoms. A description and analysis of APT data processing techniques are provided for studying the cluster structure and distribution of elements in the amorphous matrix and crystalline phases. To identify crystalline phases, data obtained using High-Resolution Transmission Electron Microscopy (HR-TEM) and Scanning Transmission Electron Microscopy (STEM), as well as X-Ray Powder Diffraction (XRPD) with synchrotron radiation source were used. The applied techniques made it possible to establish that the formation of nuclei of crystalline phases is preceded by three stages of the amorphous microwire matrix evolution. At the first stage, clusters of the first and second coordination spheres appear. At the second stage, the clusters coagulate and become more than 2 nm in diameter, the stage ends with the predominance of Co-rich and silicide Me-Si clusters. At the third stage, they grow to an average diameter of 4.5 nm, the predominance of clusters of this type remains, and the formation of nuclei of crystalline phases α-Co and Co2Si, with a size of about 8 nm, occurs. This stage is characterized by high stable soft magnetic properties. With a further increase in the heat treatment temperature, a gradual deterioration of the soft magnetic properties and further structural transformation occur – structures of joint crystalline phases from two crystalline phases α-Co and Co2Si are formed in the amorphous matrix, and crystallization occurs with the alternation of these two phases. This leads to a significant redistribution of alloy components. As a result, an amorphous barrier layer is formed in the amorphous matrix near the surface of the growing two-phase substructures, enriched in chromium and silicon; this layer affects the growth of crystalline phases, slowing it down.

Monitoring decomposition of Eu3+ doped LaPO4 nanocrystals in glass using Eu3+ as an optical probe for applications in temperature sensing

The methods to directly introduce crystals of known chemistry, size, and optical properties into a glass matrix are useful to circumvent some limitations related to the control of the growth of crystalline phases in glass-ceramics. The emission spectrum of LaPO4:Eu3+ is characteristic for highly symmetrical coordination of Eu3+ and very distinct from the emission spectrum of Eu3+ in amorphous host, which allows for its application as an optical probe. Here, Eu3+ - doped LaPO4 crystals were prepared using solid state reaction and added into various phosphate glass melt before quenching. From the changes in the micro-luminescence spectra, the decomposition occurs along with the diffusion of the Eu3+ ions into the glass confirming that the measurement of the micro-luminescence allows one to precisely track the crystal's decomposition inside the composite. It is demonstrated, for the first time to our knowledge, that the thermometric sensitivity of the Eu3+ ions can be enhanced by adding the LaPO4:Eu3+ crystals into phosphate fluoride glasses due to special separation of the crystallites during the composite preparation and also to the reduction of the self-absorption of the 5D1→7F1 emission. The composite material is promising for applications in temperature sensing.

A green synthetic approach for the morphological control of ZnO-Ag using β-cyclodextrin and honey for photocatalytic degradation of bromophenol blue

Green synthetic approaches aid control of physicochemical properties of nanoparticles and decrease the environmental footprint of the nanoparticles. Herein, novel synthesis of ZnO nanoparticles (NPs) using natural surfactants and sequential investigation of their optical, physicochemical and photocatalytic properties are conducted. This work utilizes β-cyclodextrin (βCD) and honey as surfactants during the production process. It is demonstrated that these natural surfactants have the ability to control size, shape, crystalline phase growth and dispersion of NPs (denoted as ZnO-C and ZnO-H). Subsequent coupling of ZnO NPs with Ag to form the binary nanostructures (ZnO-xAg, ZnO-C-xAg and ZnO-H-xAg) further assists controlling their physicochemical properties. With a variation of Ag NPs loading, the 3 wt% Ag loaded nanophotocatalysts were more efficient and their associated properties were revealed by various characterization techniques. Nanoparticles of different shapes were fabricated with a surface area of up to 10 m2.g−1 and crystalline sizes of 9.38 nm. Photoluminescent spectroscopy indicated that Ag nanoparticles enhanced the life span of electron-hole pairs. Thus, photodegradation of bromophenol blue (BPB) indicated enhanced NPs photoactivity upon modification with CD, honey, and Ag NPs. BPB photodegradation was > 99.84% using ZnO-H-3Ag with reaction rates of k0app=518.8×10−2min−1 and up to 75% total organic carbon was removed by ZnO-H-3Ag at a rate of 8.19×10−3min−1.

Study of crystallization mechanism of Al-based amorphous alloys by in-situ high temperature X-ray diffraction method

The role of transition metals (TMs) addition on the formation and crystallization of amorphous Al85TMs10Y5 alloys was described using in-situ high-temperature X-ray diffraction. The structural results were compared with differential scanning calorimetry and dynamical mechanical analysis to obtain detailed information about the nucleation and growth of crystalline phases. The performed analysis confirmed that Fe and Cu addition drastically changes the crystallization temperature and the phase composition of the fully crystallized alloys. While for Al85Ni10Y5 alloy, the second crystallization step is related to the formation of Al19Ni5Y3 phase, for Al85(Ni, Fe)10Y5 and Al85(Ni, Fe, Cu)10Y5 alloys crystallization of Al15Fe9Y2 phase was observed. Interestingly, the performed analysis showed that forming a homogenous amorphous phase is not necessary to obtain the best corrosion resistance. It was noted that the precipitation of the YCr2Al20 phase in the Cu-rich amorphous matrix should be a much more interesting approach.

Modulation effect on mechanical properties of nanolayered MoN/MoSiN coatings

The combination of molybdenum nitride, MoN, and molybdenum silicon nitride, MoSiN, to be a naolayered MoN/MoSiN film was developed by the reactive radio frequency, r.f., magnetron sputtering system. The MoN and MoSiN building layers were designed and fabricated with a crystalline and an amorphous/nanocrystalline feature, respectively. The effect of thickness modulation of the c-MoN and a-MoSiN layers on microstructure and mechanical properties of the MoN/MoSiN coatings were investigated. With a fixed 50.0 nm crystallines MoN building layer, the amorphous/nanocrystalline MoSiN building layer with a designed thickness of 25.0 nm would suppress the continuous growth of crystalline phases. For mechanical characterization, the change in modulation did not lead to significant influence on hardness and Young's modulus. When a large thickness ratio of c-MoN/a-MoSiN was applied, phenomenal increase in scratch and wear resistance was observed due to higher volumetric ratio of hard crystalline MoN layer and discontinuity of crystalline phase growth through building layers in the nanolayered MoN/MoSiN coatings.

Ultrastrong behaviors of a non-equiatomic Ti-Zr-Ni-Cu-Be high entropy metallic glass with ultrahigh glass forming ability

We studied the thermodynamics and kinetics of a non-equiatomic Ti32.8Zr30.2Ni5.3Cu9Be22.7 high entropy metallic glass (HEMG, ΔSconfig.∼1.44R) with a critical size for glass formation over 50 mm. The characteristic transition temperature, enthalpy of transition and specific heat capacity along with the relaxation time at different heating rate were determined using differential scanning calorimeter (DSC) measurements. It reveals that the present HEMG supercooled liquid shows the lowest thermodynamic driving force against the nucleation and growth of crystalline phases with comparing to other typical MG formers. Meanwhile, it exhibits the ultrastrong behavior near glass transition in terms of the Angell's fragility concept. The alloy has a fragility index of D* = 45.2, higher than all the typical MG formers reported so far. Both thermodynamic and kinetic factors are responsible for the ultrahigh glass-forming ability of the HEMG alloys.

Enhanced Electromagnetic Wave Absorption for Y2O3-Doped SiBCN Ceramics

Polymer-derived SiBCN ceramics (PDCs-SiBCN) are promising ultrahigh-temperature ceramics owing to their excellent high-temperature oxidation resistance and electromagnetic wave (EMW)-absorbing capability. In this paper, the microstructure evolutions, the dielectric properties, and EMW absorption properties of Y2O3-doped SiBCN ceramics were investigated. The results reveal that Y2O3 acting as a catalyst promotes the formation of SiC, BN(C), and graphite crystalline phases in the SiBCN ceramics, and these crystalline phases are constructed as conduction phases and polarization phases to enhance the EMW-adsorbing properties. The minimum reflection loss (RLmin) reaches -42.22 dB at 15.28 GHz, and the effective absorption bandwidth is 4.72 GHz (13.28-18.00 GHz). In addition, there is only 0.56 wt % mass loss for the Y2O3-doped SiBCN ceramics when they are heated from ambient temperature to 1500 °C in air, indicating that the Y2O3-doped SiBCN ceramics obtain excellent oxidation resistance at high temperature. We believe that rare metal oxidation is beneficial for the growth of crystalline phases in the PDCs, resulting in high EMW-absorbing properties and oxidation resistance. Thus, the research extends a novel method and design strategy for microstructure regulation and property enhancement of PDCs.

Crystal growth of PPS nanofibers during annealing studied by solid‐state 13C CPMAS NMR

AbstractInitial crystalline phase growth property for poly(p‐phenylene sulfide) (PPS) nanofibers during annealing are studied by means of the 13C high‐resolution solid‐state cross‐polarization/magic‐angle‐spinning NMR (13C CPMAS NMR) with spectral editing procedure using the difference in 1H spin‐lattice relaxation time in the rotating frame (T1ρH) between the crystalline and non‐crystalline phases. The PPS nanofibers are prepared by drawing the solid microfibers melted by a high‐power carbon dioxide (CO2) laser with supersonic jet velocity of 300–600 ms−1 in a vacuum chamber (CLSD method). The crystallinity and molecular orientation of the pristine drawn PPS nanofibers increase with decrease of the chamber pressure (pch). The growing process and the ordered chain packing of the crystalline phase during annealing depend on the initial chain orientation. The low pressures at pch = 30 and 10 kPa significantly relate to the initial nucleation growth of the PPS nanofibers. In the initial crystal growth of PPS nanofibers obtained at pch = 30 kPa for the low temperature annealing, the rearrangement of chains occurs, but for those at pch = 10 kPa the rearrangement does not occur. This is because the highly ordered chain alignments and packing are already achieved for PPS nanofibers obtained at pch = 10 kPa.

ОСОБЕННОСТИ ФОРМИРОВАНИЯ МИКРОСТРУКТУРЫ ГРАНУЛИРОВАННЫХ ЗАПОЛНИТЕЛЕЙ НА РАЗНЫХ ВЯЖУЩИХ КОМПОЗИЦИЯХ

This work includes a study of the microstructure of granular aggregates prepared on various binding compositions. The presented work includes three parts devoted to the analysis of the microstructures of granular aggregates taking into account the change in the percentage of the mineral filler in binding compositions. The article deals with the main aspects of the formation of the structure of granular aggregates during the hydration of Portland cement (PC 500-D0-N) and a binder composition (PC 500-D0-N + 10 % quartz sand) prepared in a vortex jet mill. The main regularities of the influence and dispersion of quartz mineral filler (fractions ≤0.16; ≤0.315; ≤0.63 mm) on structure formation during the hydration of binding components differing in the composition and particle dispersion are revealed. The paper analyzes physical and mechanical tests of the most promising samples with a study of their microstructure features. The study of the sample microstructures reveals the general regularities of the growth of crystalline phases of different densities. It is established that the introduction of 1 0% mineral fine-dispersed filler, in the form of quartz sand, contributes to the formation of sub-microcrystalline hydrate phases, which are centers of hydration, additionally binding individual grains of granular aggregates and compacting the structure of the overall system. In all samples, the formation of a block-rhythmic structure is observed, with the presence of individual block-aggregates. There is an overgrowth of microscopic pores with small crystalline neoplasms of calcium hydrosilicates. It is revealed that the structure of granular aggregates prepared on the basis of binder composition No. 1 (BK-1) has higher density than on Portland cement PC 500-D0-N.

Advanced structure research methods of amorphous Co69Fe4Cr4Si12B11 microwires with giant magnetoimpedance effect: Part 1 – Crystallization kinetics and crystal growth

The initial stage processes of nucleation and growth of crystalline phases in Co-based amorphous microwires in a glass shell were studied by processing kinetic curves using various theoretical models. The results of X-ray diffraction for research of the microstructure evolution at Synchrotron Radiation Source and High Resolution Transmission Electron Microscopy were considered. The study of the crystallization process kinetics was carried out by a non-conventional method, in particular based on data of sample magnetization changes over time and with temperature at a unique in situ vibromagnetometer. The analysis of the kinetic curves for isothermal and non-isothermal crystallization process led to the similar conclusions and made it possible to establish the values of the Avrami exponent for the initial stage of surface and bulk crystallization, to establish the dimensionality of crystal growth, and to conclude that there was no nucleation in the process of crystal growth. Based on the analysis of kinetic curves by three methods, the activation energy of the primary crystallization process was determined, its high value is associated with the presence of chromium in the alloy, which determines its nanocrystallization. The microstructure and shape of crystals were analyzed.

Free Energy of Nucleus Formation during Growth of III–V Semiconductor Nanowires

An expression for the free energy of nucleus formation from liquid phase of a catalyst during growth of III–V semiconductor nanowires (NWs) via the vapor–liquid–solid (VLS) mechanism has been derived with allowance for depletion of the number of atoms of the group V element (As) in the drop as a result of the island growth during As deposition from the gas–vapor phase. Various regimes of island formation, including a regime with growth arrest at small As concentrations in the drop have been theoretically studied. It is established that the growth arrest takes place when the As concentration decreases to an equilibrium level. The obtained results can be used in simulations of the growth kinetics of III–V semiconductor NWs, statistics of their nucleation, and NW length distribution functions, as well as for modeling of the crystalline phase growth and doping processes.

New insights into the crystallization process of sol‐gel–derived 45S5 bioactive glass

AbstractIn this work the influence of thermal treatment conditions on crystallization of a sol‐gel‐derived 45S5 bioactive glass was evaluated using DSC, XRD, TEM, EDX, and X‐ray nanocomputed tomography (nano‐CT). Temperature and time of the thermal treatment strongly influence the composition of the crystalline phases. At the onset of the glass transition temperature (600°C), combeite crystallizes as the main phase along with a calcium silicate‐phosphate phase, which decomposes into rhenanite from 2 hours of thermal treatment at this temperature. At the crystallization temperature (700°C), combeite remains as the main crystalline phase. Additionally, Na2Ca2Si2O7 crystalline phase is formed. Our results provide a basic platform for tailoring the crystalline phases by controlling the nucleation and growth of crystalline phases via thermal treatments. Different morphologies (round particles, stacked layers, toothpick‐like, and long features) were discerned by TEM as a function of temperature and time of treatment. It is the first time that bioactive glass is investigated by nano‐CT at laboratory scale. This novel technique enables the 3D visualization of features in the nanometer range, giving clear information about the volumetric distribution of phases in the sample.

Development and characterization of low temperature metallic glazes in Na2O-B2O3-SiO2 (NBS) system

This paper presents the results of an investigation into crystal formation in NBS system for glaze with metallic appearance experimentally produced by embedding metallic substances as AgNO3, BaCl2, CuSO4 and CuCO3 and their characterizations. Composition of NBS was calculated by using Seger Method. According to the quantity of components, crystal phases were marked on Na2O-B2O3-SiO2 ternary diagrams. The amount of AgNO3 (2 wt%) was kept constant that other metallic substances (BaCl2, CuSO4 and CuCO3) were added in an amount of 5 wt% as had an impact on the mechanism of crystalline phase growth. These glaze compositions were applied over the surface of the commercial bodies and fired at 1040 °C, cooled to 750 °C and then reduced in the reductive atmosphere in order to obtain metallic layer on glaze surfaces for 20 min. These glaze layers characterized under mineralogical, microstructural and chemical points of view by means of X-Ray Diffraction (XRD), optical microscopy (OM), Scanning Electron Microscopy coupled with Energy Dispersive X-ray (SEM-EDX) and Ulltraviolet Visible Spectroscopy (UV–Vis) techniques. The results showed that silver and copper particles/crystals developed near/on the glaze surfaces creating multicolored metallic shine. Diffusion of metallic particles/crystals shown on the glazed layers as Ag and Cu followed by nucleation and growth in a reductive atmosphere.

Nanorose-like ZnCo2O4 coatings synthesized via sol–gel route: morphology, grain growth and DFT simulations

Ternary cobalt-based metal oxide (ZnCo2O4) has been successfully coated onto aluminum substrate via sol–gel method. The coatings were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and UV–Vis–NIR spectrophotometry. Thermal degradation of the coatings was probed by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). Model of crystal growth kinetics and density functional theory (DFT) calculations further probed the crystalline structure evolution. The predicted ZnCo2O4 crystalline structures were confirmed by XRD and EDX. The grain growth kinetic model for ZnCo2O4, derived from Lifshitz–Slyozov–Wagner (LSW) theory, determined that the growth of crystalline phases is unaffected by the annealing temperature; however, the crystallites’ sizes decreased with the increase in precursor concentration. DFT analysis indicated that structural energy stability between the bulk state and slabs of ZnCo2O4 was at two oxygen layers (O-layers) with an optimum grain width of 17.21 A. Interestingly, the morphology of ZnCo2O4 represented a rose-like template structure formed by inter-connecting layers of nanosheets. This unique surface morphology enhanced the optical absorptance properties up to α = 70.7%.

Mathematical model of solidification kinetics of epoxy compound

A mathematical model of the solidification kinetics of an epoxy compound reflecting the effect of the technological modes of microwave treatment on its structure, physical and mechanical properties was developed. The equation of the crystalline phase growth for the case of microwave solidification of an epoxy compound, which allows the description of the mechanism of the non-thermal effect of the microwave electromagnetic field on the compound, was obtained

EXPOENTE DE AVRAMI PELA EQUAÇÃO DE JMAK PARA MÉTODO NÃO-ISOTÉRMICO DE ANÁLISE TÉRMICA

This work reports a discussion about of the general theory for phase transformations of Melh-Johnson-Avrami-Kolmogorov in process involving non-isothermal crystallization. This model allows determine as occurs the mechanism of the nucleus formation and of growth of crystalline phases during the crystallization process. To demonstrate the validity this theory, the Avrami exponent ( n ) of the LiO 2 -TeO 2 -WO 3 vitreous system was determined from DSC non-isothermal measurements. The obtained results indicate that the nucleation process is volumetric with two-dimensional or three-dimensional crystal growth. DOI: http://dx.doi.org/10.30609/JETI.2018-2.5566

EXPOENTE DE AVRAMI PELA EQUAÇÃO DE JMAK PARA MÉTODO NÃO-ISOTÉRMICO DE ANÁLISE TÉRMICA

This work reports a discussion about of the general theory for phase transformations of Melh-Johnson-Avrami-Kolmogorov in process involving non-isothermal crystallization. This model allows determine as occurs the mechanism of the nucleus formation and of growth of crystalline phases during the crystallization process. To demonstrate the validity this theory, the Avrami exponent (n) of the LiO2-TeO2-WO3 vitreous system was determined from DSC non-isothermal measurements. The obtained results indicate that the nucleation process is volumetric with two-dimensional or three-dimensional crystal growth. DOI: http://dx.doi.org/10.30609/JETI.2018-2.5566

Ultra-thin MoO3 film goes wafer-scaled nano-architectonics by atomic layer deposition

From the technical and design points of view, it is quite difficult to maintain the integrity of nano-films during the deposition process to fabricate practical devices based on ultra-thin semiconductor films. Thus, defect-free wafer-scaled development of ultra-thin quasi two-dimensional (2D) oxide semiconductor films represents serious challenges. Plasma-enhanced atomic layer deposition (PE-ALD) made it possible to fabricate ultra-thin MoO3 nano-films (4.6nm) over the wafer-scaled granular Au electrode. The detailed ALD recipe for ultra-thin MoO3 film was established and verified. The C12H30N4Mo and O2 plasma were used as Mo precursor and oxygen source, respectively. The growth of crystalline phases was observed when the ALD temperature of 250°C was employed. Higher ALD temperature resulted in an increase of growth rate over Au substrate (1.21Ǻ/cycle). The precise recipe design enabled the scalable fabrication of environmental sensors based on ultra-thin MoO3 films with precise thickness controllability. Electrochemical sensors based on the fabricated MoO3 nanostructures demonstrated reliable performance to hydrazine (N2H4) detection.