Formation Of Phase Structure Research Articles

Morphologically modified CuO nanorod structure @ stainless steel as high performing supercapacitor electrode prepared by spray pyrolysis

Copper oxide (CuO) nanorods are successfully grown onto the stainless steel substrates through varying different concentrations of non-aqueous Cu(NO3)2.3H2O by using the spray pyrolysis technique. Structural information and phase formation confirmation are carried out using X-ray diffraction. The as-grown nanorods possess a monoclinic crystal structure with the CuO phase. The growth of nanorods and morphological modifications with different molar concentrations are viewed through field emission scanning electron microscopy. It confirms morphological modifications from randomly oriented nanostructures to well oriented nano-cuboids with the increase in molar concentration of precursor solution. Further transmission electron microscopy confirms the agglomeration of interconnected nanograins to form nano-cuboids. It is observed that specific capacitance increases with an increase in the CuO nanorod size with the molar concentration of the precursor solution. As-prepared CuO electrode exhibits outstanding electrochemical performances with a capacitance of 827.40Fg-1. Encouragingly, morphologically modified CuO nanorod electrode achieves a maximum specific energy of 108.18Whkg−1 and outstanding cycling stability with 87.78% capacitive retention after 5000 cycles, which indicates a great potential for practical application. The diffusion coefficient of the electrolyte ions for the high performing CuO electrode is 2.75 × 10−17 cm2s−1, which is suitable for the supercapacitor application.

DFT, molecular docking, photocatalytic and antimicrobial activity of coumarin enriched Cinnamon bark extract mediated silver nanoparticles

• Silver nanocatalysts synthesized by simple precipitation process. • Structural phase formation shows Face centred cubic structure. • The photocatalytic degradation of cationic dye and antimicrobial activity were examined. • Silver nanocatalyst shows maximum degradation efficiency of 96% for MB. Water pollution is a severe and urgent issue on a global scale. Nanoparticles are capable of purifying contaminated water. Using plant extracts for green nanoparticle manufacturing minimises hazardous chemicals or energy requirements. This paper focuses on the eco-friendly synthesis of plasmonic Ag nanoparticles from cinnamon-derived natural materials and its potential in biomedicine, water treatment, and catalysis. An SPR peak confirmed the reduction of Ag + ions to Ag o nanoparticles at 449 nm in UV–Vis spectroscopy. The XRD and TEM analyses indicate FCC and polydisperse nanoparticles with a spherical shape. Under visible light illumination, the photocatalytic activity of plasmonic AgNPs was evaluated against Methylene Blue (MB) dye. After 120 minutes, plasmonic Ag NPs displayed high antibacterial activity and 97% photo degradation efficiency. Metallic Ag NPs exhibited more catalytic activity than commercial TiO 2 NPs. According to DFT experiments, coumarin in cinnamon bark reduces Ag + ions to Ag o . To the best of our knowledge, the current paper is the first to use cinnamon-mediated plasmonic Ag photocatalysis for efficient antibacterial action and degradation of MB dye.

Direct synthesis of nanosized CHA zeolite free of organic template by a combination of cations as structure directing agents

There is an increasing demand for porous materials able to separate the components of natural gas, mainly CH4 and CO2. Flexible small pore zeolites are interesting candidates due to their high sorption capacity and ability to selectively separate molecules of similar sizes. This selectivity comes from their small pores, large cavities, and pore shapes which can be controlled by the introduction of different extra-framework cations such as Na+, K+, Cs+. Furthermore, the extra-framework cations selectively provide access to the pores and cages of the zeolite depending on the nature of the molecules present. The strategy to prepare CHA-type zeolites across a range of particle sizes, from micron-sized dimensions to nanocrystals with a size of 50 nm, was investigated. The quantities of extra-framework cations and the hydrothermal conditions were optimised in order to avoid the formation of secondary structural phases and selectively target the CHA phase. The CHA-type zeolites were characterised by electron microscopy, elemental analysis, MAS NMR and FTIR spectroscopy, and PXRD. The Si/Al ratio of the obtained CHA zeolite was between 1.7 and 2.6 which is ideal for gas separation applications. The nanosized as-synthesised CHA zeolite (Si/Al = 2.4) demonstrates a high CO2 storage capacity (4.6 mmol/g) making it an ideal candidate for gas separation applications.

Imitating Spiders to catch flying insects: Realizing high-strength bonding of bamboo scraps/magnesium oxychloride lightweight composite interface

Compatible interface is the key to designing low-carbon building materials containing plant fiber. Moisture migration causes steric hindrance at interfaces, resulting in materials with poor two-phase interface compatibility and low mechanical strength. Drop load presents a serious threat to the structural safety of future houses. Firmer cementation in composite becomes an urgent problem. We report on a strategy using polysaccharide chains between two different phases, and design high-strength adhesion interface. This new design is inspired by the behavior of spiders to catch flying insects. The presence of hydroxyl and amino groups on the spider silk surface allows binding of flying insects with high strength and using only small contact area. To mimic that strategy, MgO was used for orderly crystallization on the polymer chain and active hydroxyl groups with high specific surface area achieves multidimensional and multi-site adhesion of bamboo scraps. Improved interfacial compatibility facilitates the formation of heterogeneous but continuous phase structure. The compressive stress reaches 4.66 MPa and softening factor is 0.74 for density of 0.37. The designed material is an advanced composite in construction and decoration. Its low-loading characteristic can reduce carbon footprint calculations, suggesting this strategy has significant potential for future development.

Construction and high throughput exploration of phase diagrams of multi-component organic blends

During solvent-based fabrication of organic blends the blend composition changes significantly as solvent is removed from the blend triggering phase transformations and structure formation. The choice of the solvent in conjunction with the processing pathways (i.e. quench profile) affects this process. Using a combination of solvents as well as solvent additives has produced favorable structures for organic electronic applications. However, selecting which solvent, solvent blend, or additive to use becomes a combinatorially complex problem. Successful efforts to pre-screen based on solubility spheres, and in general thermodynamics arguments, suggest that the phase diagram can be a useful design tool for solvent composition selection. Here, we report a workflow for high-throughput construction of a library of phase diagrams, followed by an exploration of the solvent selection space guided by the library. Our analysis pipeline consists of (i) a convex-hull based method to determine phase diagrams of multi-component mixtures; and (ii) high throughput analysis of a large set of phase diagrams using dimensionality reduction coupled with clustering. Using this workflow, we illustrate exploration of solvent and the associated design rules for a model material system used in organic thin films fabrication. We envision this workflow to be useful for rapid exploration and selection of multi-component solvent blends and additive formulations.

Theoretical and experimental investigations: Synergetic effect of Yb–Cu substitution on different properties of hexagonal ferrites

This research project was designed to understand the synergetic effect of trivalent ion Yb3+ and divalent ion Cu2+ co-substitution on different properties of X-type hexagonal nano ferrites. For this purpose, a series of Sr2-xNi2YbXFe28-YCuYO46 X-type hexagonal nano ferrites with concentration (x = 0, 0.02, 0.06, 0.1 & y = 0, 0.1, 0.2, 0.3) was synthesized by adopting the sol gel method. The XRD (X-ray diffraction) results of synthesized samples reveal the formation of single phase for all samples with space group P63/mmc. All the XRD peaks coincided with the reference card (ICDD # 01-073-2034). The theoretical fitting was performed by implementing the Rietveld refinement method to further check the single phase of the samples. The crystallite size and unit cell volume decrease with increasing Yb3+ and Cu2+ contents. The VSM results indicated the hard magnetic nature of all the synthesized materials and theoretically calculated particle size was varied in the range between 9.2 and 11.5 nm. The saturation (Ms) and remanence magnetization (Mr) decreased with the increase in Yb–Cu contents. The value of coercivity (Hc) was first increased and then decreased with the substitutions. Furthermore, the Law of approach to saturation (LAS) was employed to theoretically fit the hysteresis loops. The mixture of spherical and rod shape grains was observed in the SEM micrographs. By adopting the line intercept method, the calculated grain size was varied in the range from 0.691 to 1.33 μm. FTIR spectrum exhibits no extra absorption band due to residual material which also confirms the formation of single hexagonal phase structure. The Thermogravimetric (TGA) analysis divulged the weight losses due to removal of nitrate, vaporization of water molecules and removal of organic compounds at different temperatures. The reflection loss (RL) values have been enhanced with the substitution of Yb–Cu contents.

Improving the wettability and corrosion behavior of Cp-Ti by applying anodization surface treatment with the addition of boric acid, graphene oxide and hydroxyapatite

In order to increase the surface wettability and corrosion resistance of commercial pure titanium (Cp-Ti), TiO2 anodic films were produced by anodization method using H2SO4/H3PO4 solution mixtures. Boric acid, graphene oxide and hydroxyapatite were added to the H2SO4/H3PO4 solution and their electrochemical properties and surface wettability were investigated. Characterization of anodic films was achieved by XRD, SEM, Raman and surface tension meter. Also, electrochemical analyses were performed to determine the corrosion behavior of anodic films. The differences in the morphological and chemical structures of the anodized samples played an important role in determining the surface wettability and electrochemical properties. While the open porous structures, which formed after anodization, samples increase the surface wettability, the best wettability was obtained in the anodic film with the addition of hydroxyapatite. Corrosion resistance of Cp-Ti improved due to the formation of anatase and rutile phase structure in anodic films.

Thermal property and failure mechanism of LaDyZrO thermal barrier coatings by electron beam physical vapor deposition

Thermal barrier coatings (TBCs) have attracted much interest several decades ago. Lanthanum zirconate La2Zr2O7 is known for its high melting point and good thermal stability in aircraft engine environment. The thermal property and failure mechanism of the advanced TBCs still remain a challenge. This study focuses on phase, thermal expansion coefficient, microstructure, composition, thermal durability, and failure behaviors in the LaDyZrO/YSZ/NiCoCrAlYHf TBCs. The LaDyZrO and YSZ ceramic layers are deposited by EB-PVD, and NiCoCrAlYHf metallic layer is deposited by AIP-PVD. The as-deposited TBCs exhibit good thermal cycling life and thermal shock life at 1100 °C due to the improvement of TEC, the formation of dual phase structure and columnar structure. The locally broken region of the YSZ/TGO interface, LaDyZrO/YSZ interface and further the LaDyZrO layer would facilitate propagation of the interface instability. The element diffusion and cracks evolution might be two critical factors for the failure mechanism of LaDyZrO/YSZ/NiCoCrAlYHf TBCs. This study of thermal property and failure mechanism would be used to explain the element diffusion behavior and microstructure evolution of other advanced TBCs.

Determination of dual magnetic phases and the study of structural, dielectric, electrical, surface morphological, optical properties of Ce3+ substituted hexagonal ferrites

The current research project was designed to investigate the influence of Ce3+ substitution on different properties of β-type hexagonal ferrite KCexFe11−xO17 (x = 0, 0.02, 0.06 and 0.1) and to verify the experimental obtained results through theoretical calculations/modeling by performing the curve fittings. For this purpose, the sol-gel auto-combustion route was adopted to synthesize the samples. The X-rays diffraction (XRD) analysis divulged the formation of single phase structure for all samples. It was observed that the structural parameters such as lattice constants a (Å) and c (Å), dislocation density (g/cm3), crystalline size (nm) and unit cell volume V (Å)3 varied with Ce3+ concentration. Moreover, the results obtained from Williamson Hall (W-H) technique revealed that both the pure and Ce-substituted samples exhibited the positive tensile micro strain. The formation of single phase hexaferrite was also confirmed by Fourier transform infrared (FTIR) spectra. The dielectric constant, dielectric loss and tangent losses have large values at low frequency region and declined with increase in frequency. The ac conductivity revealed the increasing trend with enhancement in frequency. The Cole-Cole plot specified the influence of both grains and grain boundaries for the capacitive and resistive nature of the material. The P-E (Polarization vs electric field) loops indicated the increase of resistive nature of sample with Ce3+ contents. The DC electrical resistivity of the sample at voltage range (−200 to 0 V) was found to be diminished with substitution of Ce3+ content. The M-H loops for all the samples represented the alteration in saturation magnetization (Ms) and coercivity (Hc) with the substitution of Ce3+ contents. Consequently, the M-H loop of one concentration surprisingly exhibited both the ferromagnetic and diamagnetic behavior simultaneously.

Phase classification of multi-principal element alloys via interpretable machine learning

There is intense interest in uncovering design rules that govern the formation of various structural phases as a function of chemical composition in multi-principal element alloys (MPEAs). In this paper, we develop a machine learning (ML) approach built on the foundations of ensemble learning, post hoc model interpretability of black-box models, and clustering analysis to establish a quantitative relationship between the chemical composition and experimentally observed phases of MPEAs. The originality of our work stems from performing instance-level (or local) variable attribution analysis of ML predictions based on the breakdown method, and then identifying similar instances based on k-means clustering analysis of the breakdown results. We also complement the breakdown analysis with Ceteris Paribus profiles that showcase how the model response changes as a function of a single variable, when the values of all other variables are fixed. Results from local model interpretability analysis uncover key insights into variables that govern the formation of each phase. Our developed approach is generic, model-agnostic, and valuable to explain the insights learned by the black-box models. An interactive web application is developed to facilitate model sharing and accelerate the design of MPEAs with targeted properties.

Effect of stacking sequence on the structural ordering and phase formation in the sequentially deposited copper zinc tin sulfide thin films

Effect of stacking sequence on the structural ordering and phase formation in the sequentially deposited copper zinc tin sulfide thin films

The Effects of Copolymer Compatibilizers on the Phase Structure Evolution in Polymer Blends-A Review.

This paper summarizes the results of studies describing the effect of block and graft copolymers on the phase structure formation and evolution in immiscible polymer blends. The main phenomenological rules for prediction of the copolymer compatibilization efficiency are briefly described and compared with selected experimental data. The results of the theories of equilibrium distribution of a copolymer between the blend interface and the bulk phases and its effect on the blend interfacial tension are summarized. The theories of the compatibilizer effect on the droplet breakup in flow are analyzed. The mechanisms of the copolymer effect on the coalescence of droplets in flow are compared and their effect on the droplet size is shown. The problems of reliable description of the effect of a copolymer on the coalescence in quiescent state are presented. Obstacles to derivation of a realistic theory of the copolymer effect on the competition between the droplet breakup and coalescence are discussed. Selected experimental data are compared with the theoretical results.

Influence of Temperature on Structural and Magnetic Properties of Gd3AlxFe5−xO12 (x = 2)

AbstractThis research work explores the effect of sintering temperature on morphology and magnetic properties of aluminum substituted gadolinium iron garnet Gd3AlxFe5−xO12 (x = 2). Sol–gel autocombustion method is adopted to prepare Gd3AlxFe5−xO12, and further sintered at 900, 1000, and 1100 °C. X‐ray diffraction (XRD) confirms the formation of garnet phase structure. Fourier transformation infrared ray further stands with result of XRD that reveals the presence of garnet phase. Field emission scanning microscope analysis shows the formation of average grain size 4, 6, and 13 nm for 900, 1000, and 1100 °C, respectively. Vibrating sample magnetometer results show that the coercivity decreases with increases in temperature, which indicates that this material can be used in switching devices. The calculated value of microwave operating frequency reveals that these materials can be used in ultrahigh‐frequency region.

Effect of Nitrogen Doping on Structural and Optical Properties of TiO2 Nanoparticles

AbstractTiO2 has materialized as an excellent heterogeneous photocatalyst for environmental and energy fields, including air and water splitting. It has 3.2 eV band gap with the absorption edge at near‐UV light. Tuning of the band gap of TiO2 into visible region is achieved by the doping of nitrogen. The optimum compositions of N doped TiO2 NPs are prepared by sol‐gel method at room temperature. The structural phase formation of materials is analyzed by XRD studies, which shows anatase phase. The crystallite size is calculated from XRD data, which is in nanometer range. FTIR spectra are studied to confirm the O‐Ti‐O, O‐Ti‐N bonding in N‐doped TiO2 and formation of ‐OH groups on the surface, which can extensively affect the TiO2 band structure and surface of catalyst. The morphology of samples is investigated by FESEM and HR‐TEM. The compositional stoichiometry is confirmed by EDAX analysis. An optical study is confirmed by UV‐Visible spectrophotometer.

Effect of energy density on the microstructure and properties of the CrFeCoNiNb high-entropy cladded layer

A synergistic combination of mechanical properties and corrosion resistance property is desired for most ocean engineering structural applications. In this paper, we prepared a high-entropy alloy (HEA) cladded layer of composition CrFeCoNiNb (atomic %). We aim to attain a balance between the mechanical property and the corrosion resistance property by adjusting the energy density. The prepared CrFeCoNiNb cladded layer with an energy density of 116.7 J/mm2 exhibited excellent mechanical properties and high corrosion resistance. The improved mechanical properties are attributed to fine grain strengthening, solid solution strengthening, and dispersion strengthening. Whereas, the excellent corrosion resistance is due to the formation of Laves corrosion-resistant phase structure and the compact passivation film. The variation of the mechanical properties and corrosion resistance with different energy densities are attributed to the phase composition. The proportion of the Laves phase decreases first and then increases with the increase of energy density, which is the main reason that the microhardness of the cladded layer follows a similar trend. The outcome of our research suggests that the prepared CrFeCoNiNb cladded layer could be explored to realize surface strengthening of load-bearing parts in marine engineering equipment.

Method to identify the phase structures of high entropy alloys with modified lattice distortion enthalpy

Severe lattice distortion is one of important characteristics of high entropy alloys (HEAs) and exercises considerable influence over phase structures, and atomic volume V is thought to be the key factor for lattice distortion. In the present work, the calculation of V was modified by taking the stacking density effects into consideration, and the calculation of lattice distortion enthalpy (∆HLD) caused by elastic lattice distortion for HEAs was optimized accordingly. With this method, two phase structure formation rules were proposed: valence electron concentration(VEC)−∆HLD rule for crystal structure of solid solution and chemical enthalpy(∆Hchem)−∆HLD rule for phase composition. The prediction effect of these two rules were verified by analyzing 100 existing HEAs, and the intrinsic effect of lattice elastic distortion on the phase formation of HEAs were discussed. The results of the research would be helpful in the composition design of HEAs.

Luminescence enhancement of La4Ti9O24:Eu3+ red-emitting phosphors via cation-substitution of M (Ga, Nb, Ta, Zr, Al) ions

Eu3+- and M (Ga3+, Nb5+, Ta5+, Zr3+, Al3+)-co-doped La4Ti9O24 phosphors were prepared by the solid-state reaction method. The structural phase formation, luminescence properties, and possible LED-lighting application were investigated. The undoped La4Ti9O24 shows an indirect transition with a band-energy of 2.88 ​eV La4Ti9O24 has a broad intrinsic emission band (350–700 ​nm) peaked at 530 ​nm (2.34 ​eV) at 300K. Eu3+-doped La4Ti9O24 presents red luminescence from 5D0→7FJ (J ​= ​0, 1, 2, 3, 4) transitions, which was obviously enhanced with the cation-substitution of M (Ga3+, Nb5+, Ta5+, Zr3+, Al3+) on Ti4+ sites in the lattices. The typical thermal quenching of La3.72Eu0.28Ti8.55M0.45O24 (M ​= ​Al) phosphor is ΔE ​= ​0.342 ​eV. Importantly, the optical excitation of the samples fit well with the commercial LED-chip because of its efficient absorption in near-UV region (395 ​nm) and blue (465 ​nm) wavelength region. The red-LED device packaging with the optimal phosphor was achieved, which has a luminous efficiency of 42 lm/W with a working current of 200 ​mA and a testing voltage of 3.2 ​V. The experiments suggest that the phosphor could be potential for solid-state LED-lighting and display.

Compatibility and high temperature performance of recycled polyethylene modified asphalt using molecular simulations

ABSTRACT The objective of this study was to explore the interaction mechanism between recycled polyethylene (RPE) and base asphalt to reveal the microscopic mechanism of the two–phase structure formation, separation, and high–temperature stability of RPE–modified asphalt. Density functional theory (DFT) and molecular dynamics (MD) simulations were used to explore the interaction of RPE–modified asphalt at the atomic and molecular scales, and the simulation results were verified by fluorescence microscopy and dynamic shear rheology experiments. The results show that the binding energy of RPE with light components (aromatics and saturates) (730–1030 Ha) was smaller than that of asphaltenes with light components (2750–4330 Ha) in the following order of magnitude: phenol > pyrrole > thiophene > RPE. The charge transfer numbers of RPE with asphalt molecules indicate that RPE interacted weakly with asphaltenes and resins. In addition, MD simulation results show that RPE elevates the diffusion coefficient of asphalt molecules. The two–phase structure of RPE–modified asphalt was observed using fluorescence microscopy, and the RPE phase became larger with increasing development time. The dynamic shear rheology experiment results show that RPE reduced the damping factor while enhancing the complex modulus and rutting factor of asphalt.

Significant magnetic, dielectric and magnetodielectric properties of CuO nanoparticles prepared by exploding wire technique

The CuO nanoparticles, prepared by exploding wire technique (EWT) followed by annealing in oxygen atmosphere at 900 °C, have been studied for phase purity and structure formation by employing X ray diffraction (XRD) method. Rietveld refinement and Debye-Scherrer analyses ensured the formation of monoclinic single phase of CuO nanoparticles with an average crystallite size of ~ 21 nm. Irregular shape nanoparticles in the size range of 5–30 nm were observed by Transmission Electron Microscopy. The temperature dependent (5–300 K) magnetization measurements have been performed to ascertain the magnetic properties of the prepared nanoparticles, which indicated the antiferromagnetic behavior around 230 K. The temperature dependent (10–300 K) dielectric measurements in 0 T and 1.3 T external magnetic fields demonstrated the frequency dependent dispersive behavior of CuO nanoparticles in the temperature range 100–200 K. The dielectric relaxation mechanism of CuO nanoparticles was further analyzed and found to follow the Arrhenius like behavior. Finally, we could observe that the Variable range hopping (VRH) is more precise in present case of CuO nanoparticles. Notably, the magnetodielectric response (MDR) of the order of 2.5 is also observed at 12 kHz frequency at the temperature around 150 K in the optimal magnetic field of 1.3 T. This proves to be an uncommon interesting property of prepared CuO nanoparticles and may lead to new technological applications.

Effect of high Fe content on the microstructure, mechanical and corrosion properties of AlCoCrFeNi high-entropy alloy coatings prepared by gas tungsten arc cladding

Abstract Arc cladding high-entropy alloy (HEA) coatings have the advantages of low cost and flexibility. It exhibits economic value to increase the proportion of Fe element in HEA systems. As a result, low-cost AlCoCrFeNi (Fe content of 42.5 at.%, 44.9 at.%, 47.5 at.%, 50.4 at.%) HEA coatings are prepared by gas tungsten arc (GTA) cladding and their microstructure, mechanical properties, and corrosion properties are investigated by XRD, SEM, EBSD, microhardness, nanoindentation, OCP, potentiodynamic polarization, and EIS. The valence electron concentration (VEC) plays an important role in the formation of phase structure. With the increase of Fe content, the phase structure of coating alloys changes from BCC to BCC + FCC, and the morphology changes from equiaxed grains to a dendritic structure. Coating alloy with higher Fe content displays lower microhardness and more active creep deformation due to the higher FCC fraction. The dual-phase (BCC + FCC) structure induces galvanic corrosion and deteriorates the corrosion properties. This work contributes to the fabrication of large-thickness and large-area HEA coatings at a low cost and provides an experimental basis for Fe-rich HEA design.