Diffraction Properties Research Articles

Surface Integrity of Cryogenically Finished Additively Manufactured and Conventional Ti-6Al-4V Alloy

Additive manufacturing (AM) is used for the fabrication of solid components of complex geometries for customized applications. However, AM-fabricated components frequently require finishing operations such as abrasive grinding, which causes a different surface characteristic compared to the conventionally manufactured components. Thus, it is essential to study the effect of process parameters and the heat treatment on surface quality of the AM components because these may behave differently to the conventional manufactured components. In this study, surface characteristics of AM samples of Ti-6Al-4V with a cryogenically cooled finishing operation is compared with that of conventionally processed samples. The samples under investigation were fabricated by two different methods, namely, Direct Metal Laser Sintering (DMLS) and conventional processing. The effect of the two processes on surface characteristics, such as microhardness, surface roughness, X-ray diffraction (XRD), and mechanical properties has been studied. The average surface roughness from cryogenic grinding was reduced by 27.25% and 23.15% for the AM, and 30.08% and 29.13% for conventional samples, as compared to dry and moist conditions, respectively. The finished DMLS and conventional samples showed increase of microhardness by 14.07%, 14.27%, 17.54% and 17.48%, 8.06%, 38.68%, in dry, moist, and cryogenic conditions, respectively. In cryogenic conditions, as the DOC and table feed increased, a greater increase in peak broadening was observed. The peak broadening in XRD of finished DMLS components indicates that a significant level of plastic deformation occurred compared to the finished conventionally manufactured Ti-6Al-4V samples, which suggests that the DMLS samples are more sensitive to the finishing process. Compared to dry and moist grinding, cryogenic grinding was found to have the smallest grains in the layer just below the surface. The impact of cryogenic cooling on surface properties of AM Ti-6Al-4V samples is higher as compared to that on conventionally processed Ti-6Al-4V samples.

Phase evolution and strong temperature‐dependent electrostrictive effect in (1−x)Pb(Mg1/3Nb2/3)O3‐xPbTiO3 solid solutions

Abstract(1−x)Pb(Mg1/3Nb2/3)‐xPbTiO3 (PMN‐xPT) ceramics with x ranging from 0.1 to 0.3 were synthesized by solid‐state reaction method. X‐ray diffraction, dielectric and ferroelectric property characterizations were systematically investigated. As x rises, the PMN‐xPT transitions from a cubic to a rhombohedral phase, resulting in an enhancement in ferroelectricity. Our findings show that the electrostrain and longitudinal electrostrictive coefficient Q33 both increase and then decrease within a critical region located between the depolarization temperature TFR and Tm (corresponding to the maximum permittivity), demonstrating strong temperature‐dependent characteristics. In x = 0.2, the maximum Q33 of 0.0361 m4/C2 is obtained, and a phase diagram of studied system is built. Our findings not only shed light on the phase evolution in this system but also reveal a strong temperature‐dependent electrostrictive effect that can be used to improve electrostrains in PMN‐based solid solutions if the critical region can be regulated to a suitable temperature region using engineering strategies.

Stabilizing the anti-ferroelectric phase in NaO–Nb2O5–CaO–B2O3–SiO2–ZrO2 glass-ceramics using the modification of K+ ion

NaNbO3 anti-ferroelectric (AFE) material exhibits a unique and irreversible phase transition, which makes it change into ferroelectric phase and prevents its implementation in high energy storage material. In this work, we use an approach to stabilize the anti-ferroelectric phase at room temperature by the modification of K+ in NaO–Nb2O5–CaO–B2O3–SiO2–ZrO2-xK + glass-ceramics. The correlation between K+ content and anti-ferroelectric stability is studied through the X-ray diffraction, microstructure, and dielectric properties. It is found that ferroelectric phase gradually transforms to anti-ferroelectric phase first and then anti-ferroelectric phase disappears with K+ doping in glass-ceramic due to two mechanisms that the un-crystallized modifier K+ into glass network reduce the connectivity of the glass network, the activation energy needed for crystallization and the tolerance factor (t), besides overmuch K+ into NaNbO3 crystalline phase leads to the increase of tolerance factor and the production of impurity phase. The phase transition has been confirmed through the double polarization loops, AFE phase and permittivity peak. The results show that the K+ doped into NaO–Nb2O5–CaO–B2O3–SiO2–ZrO2-xK + glass system can effectively stabilize AFE phase, when x＞4%, the stability of NaNbO3 anti-ferroelectric phase will decrease and impurity phases will precipitate in glass-ceramic.

Thermally crosslinked electrospun nanofibrous mat from chrome-tanned solid wastes for cationic dye adsorption in wastewater treatment

Chrome-tanned solid wastes from the tannery were used to extract collagen hydrolysate (CH) for the fabrication of electrospinning nanofibrous mat with polyvinyl alcohol (PVA) to remove cationic dye from wastewater. The nanofibrous mat was thermally crosslinked by heat curing to make it stable in neutral, acidic, and basic environments. The prepared nanofibrous mat was characterized by attenuated total reflectance infrared spectroscopy (ATR-IR), thermogravimetry (TGA), X-ray diffraction (XRD), and water dissolution properties. The detailed experimental results revealed that the nanomat prepared from CH: PVA (2:3) yielded better stability in an aqueous solution after thermal crosslinking. The nanofibrous mat was used as adsorbent and its adsorption properties were evaluated from the adsorption behaviour of methylene blue (MB), a common cationic dye. The adsorption results demonstrated that the nanomat showed maximum adsorption capacity of 99.9 mg g−1 with 88.8% removal efficiency at pH 12. The adsorption parameters were optimized and revealed to be highly pH sensitive, with 12.0 being the optimum pH for the highest dye removal. The experimental results revealed that the adsorption capacity of the nanofibrous mat grew with increasing initial dye concentration and decreased with increasing adsorbent doses. The thermodynamic study indicated that the adsorption kinetics (R2 > 0.99) followed pseudo-second-order equation, and the equilibrium data was the best suited by the Langmuir model (R2 > 0.99). On the other hand, the electrospun nanofibrous mat showed significantly better adsorption than the prepared CH-PVA composite film. The results for cationic dye adsorption suggest that the potential broader applications of collagen hydrolysate-based nanofibrous mat for pollution control may include its use as potential adsorbent for wastewater treatment.

Synthesis and crystal structure of a new three-dimensional Pb(II) hole structure coordination polymer based on based on 5-(3′,4′-Dicarboxylphenoxy)-isophthalic acid

A new Pb(II) polymer [Pb(dic)]n 1 (H4dic = 5-(3′,4′-Dicarboxylphenoxy) -isophthalic acid) was synthesized. synthesized under hydrothermal conditions. The compound crystallizes in the Triclinic system, space group P-1 with a = 7.3690(2), b = 11.0528(3), c = 11.2613(3) Å, α = 62.4120(10)°, β = 83.7290(10)°, γ = 75.6590(10)°, V = 787.58(4) Å3, Z = 2, Mr = 774.60, Dc = 3.266 Mg/m3, μ = 21.411 mm−1, F(000) = 696, the final R = 0.0240 and wR = 0.0610 for 2923 observed reflections with I > 2σ(I). The compound presents a three-dimensional (3D) network extended by dic4- anions in which the dic4- anions employ a chelating coordination mode. Infrared spectroscopy, elemental analyses, thermogravimetric analysis and the single-crystal X-ray diffraction properties of 1 are also investigated.

STUDY THE EFFECT OF ADDING A pbO NANOPARTICLE WITH A PERCENTAGE OF 0.3 OF Bi AND AN ADDITION OFF SrTiO₃ NANOPARTICLES OF 0.1,0.3,0.5 OF Ba ON THE STRUCTURAL,ELECTRICAL AND MAGNETIC PROPERTIES OF THE SUPERCONDUCTING COMPOUND(Bi₂Ba₂Ca₂Cu₃O₁₀₊δ)AT HIGH TEMPERATURES

Four samples of the compound (Bi₂Ba₂Ca₂Cu₃O₁₀₊δ) were prepared by solid-state reaction method, using annealing method, at a temperature of 800 ℃ and under hydraulic pressure of 8 tan/cm² by partial substitution of the nanoparticle lead by 0.3 from bismuth, strontium and titanium nanoparticles at a ratio of (0.1,0.3,0.5) of the element barium Ba of the compound. Electrical tests showed an increase in the value of the critical temperature Tc when compensation the material with a value of X = 0.3 for the PbO nanoparticle values of Bi and y = 0.1 compensation for the values of SrTiO₃, and from the element Ba, where the critical temperature Tc reached a value of 146.5 k and When compensation the substance with a value of x = 0.3 for the values of pbO nanoparticle from the element Bi and y = 0.3 for the values of SrTiO₃ from the element Ba, the highest increase in the value of the critical temperature Tc was 143.5 k, but it decreased when compensation the substance with x =0.3 for the values of the PbO nanoparticle From the Bi element and y = 0.5 compensation for the values of SrTiO₃, from the Ba element to 142.5 K. The structural properties of the X-ray diffraction of the models showed the presence of a certain phase in the three values with varying differences in the dimensions of the network a, b, c with a clear increase in the dimension c. When examining the samples with a fesem device with a magnification rate of 500kx ---100.00kx, it was found that the average particle size of the best samples was 27.48 nm at the sample X=0.3 and y=0.1. The images of the four models show very high-resolution images and are very detailed, and it appears that light structures belong to the light elements and dark areas belong to the heavy elements. The study under consideration showed the magnetic properties through the hysteresis curve of the samples and the relationship between the saturation magnetism Ms and the remanence magnetization Mr and the coercive force Hc that the hysteresis rings formed in the superconducting samples are narrow and there is an inverse relationship between the tightness of the rings and the improvement of the critical temperature Tc.

Magnetically Tunable One-Dimensional Plasmonic Photonic Crystals.

Integrating plasmonic resonance into photonic bandgap nanostructures promises additional control over their optical properties. Here, one-dimensional (1D) plasmonic photonic crystals with angular-dependent structural colors are fabricated by assembling magnetoplasmonic colloidal nanoparticles under an external magnetic field. Unlike conventional 1D photonic crystals, the assembled 1D periodic structures show angular-dependent colors based on the selective activation of optical diffraction and plasmonic scattering. They can be further fixed in an elastic polymer matrix to produce a photonic film with angular-dependent and mechanically tunable optical properties. The magnetic assembly enables precise control over the orientation of the 1D assemblies within the polymer matrix, producing photonic films with designed patterns displaying versatile colors from the dominant backward optical diffraction and forward plasmonic scattering. The combination of optical diffraction and plasmonic properties within a single system holds the potential for developing programmable optical functionalities for applications in various optical devices, color displays, and information encryption systems.

Asymmetric acoustic metagrating enabled by parity-time symmetry

Passive parity-time (PT) symmetric metamaterials as a fundamental carrier to investigate non-Hermitian systems have attracted significant interest, but previous studies have rarely focused on the diffraction properties of the PT system, especially the diffraction effect in the metasurfaces with phase gradient modulation. Here, by merging two concepts of phase gradient and PT symmetry together, we design and study a non-Hermitian acoustic gradient metasurface (i.e., metagrating). We show that the PT symmetry breaks spatially the symmetry of reflected wave diffraction in the acoustic metagrating, making it an asymmetric mirror. In particular, at the PT-ensured exceptional point, for incident waves from one side, such metagrating behaves as a phase gradient metasurface, in which high-efficiency retroreflection governed generalized Snell's law occurs. For an incident wave from the opposite direction, such a metagrating is a common grating, whose diffraction in the reflection follows the common diffraction equation. Our work builds a bridge connecting the phase gradient and passive PT symmetric system, enriching the methods for wavefront manipulation and exhibiting potential applications in the design of multifunctional acoustic devices.

The development of ultra-high aluminium graphene metal matrix composites (MMC) and improved the thermo-mechanical properties

Powder metallurgy has made it easier to develop Ultra high Al-Gr (5 wt% Gr) composite materials for commercial solar thermal collectors. This work seeks an optimum aluminumgraphene composite with superior thermo-mechanical properties for the thermal collector. Experimentally found that an AMMC matrix with 1.0 wt% of Gr has 282 W/mK thermal conductivity, 129 percent developed than Al (123 W/mK), and also found Al+Gr has a lower thermal expansion coefficient than pure Al. Predicted different composite densities and focused to retain 96.5 percent of aluminum density after sintering. Investigated analytical techniques and included some investigation like Raman spectroscopy, X-ray diffraction, FESM, and electricity-dispersive X-ray grain size and property and also identified high-quality composites and predicted their homogeneity and invulnerability. Predicted suitable Sintering temperature was 626 degrees Celsius which increased from 300 degrees Celsius. Energy and thermal conductivity were found that increases with increasing temperature and compared to pure Al. According to this investigation, when increased the graphene weight percentage proportion from 0 to 5.0 wt%. Results show that conductivity increases from 210 to 412 W/mK and mechanical characteristics slightly drop from 16 to 19% as pH rises from 5 to 5.5. Based on this investigation Al+Gr composites may be used for solar thermal collectors and heat sinks and also appropriate ultra-high Al+5.5 wt% suitable for solar collectors.

Evaluating residual stresses in compositionally graded TiN films via ab initio and Rietveld simulation

The grazing incidence X-ray diffraction (GIXRD) stress measurement method, based on the classic sin2ψ method, is a well-established procedure for the evaluation of compressive residual stresses (CRS) in thin deposited films. Problems arise when using this approach in single-phase compositionally graded films, since both mechanical and diffraction properties vary with film depth. A method of obtaining CRS gradient was developed which consists in simulating a stressed GIXRD pattern via Rietveld simulation and ab initio obtained X-ray elastic constants (XECs) in order to evaluate the stress profile across the film. This work successfully describes the CRS profile of compositionally graded TiN films obtained by Grid Assisted Magnetron Sputtering (GAMS), insofar as the biaxial stress assumptions are valid and within the limits imposed by the sin2ψ method.

Application of machine learning to reveal relationship between processing-structure-property for polypropylene injection molding

Revealing relationship between processing–structure-property using machine learning (ML) is beneficial to shorten the development cycle of polymer materials, which could be a promising solution to break through the traditional mode of trial-and-error. In this work, the quantitative data of processing field, polymorphic structure and mechanical properties of samples are successfully obtained based on microfocus wide-angle X-ray diffraction and mechanical property measurements, which provides the dataset for the application of machine learning. An initial step toward predicting the contents of polymorphic structure (α and β) and mechanical properties of isotactic polypropylene injection molding is taken by applying four algorithms of machine learning to establish regression models. The importance of processing descriptors is further analyzed. The prediction models for the contents of polymorphic structure and mechanical properties demonstrate satisfactory performance (R2max = 0.95). Compared with the prediction for the content of α-crystals, the results of feature importance analysis indicates that the injection pressure and shear rate of filling end in the processing descriptors charge higher contribution to the prediction for the β-crystals. And mold temperature plays an important role in predicting mechanical properties, which is consistent with the results of the signal-to-noise (S/N) ratio analysis.

High pO2 Flux Growth and Characterization of NdNiO3 Crystals

Single crystals of the perovskite nickelate NdNiO3 with dimensions of up to 50 μm on edge have been successfully grown using the flux method at a temperature of 400 °C and oxygen pressure of 200 bar. The crystals were investigated by a combination of techniques, including high-resolution synchrotron X-ray single-crystal and powder diffraction and physical property measurements such as magnetic susceptibility and resistivity. Resistivity measurements revealed a metal-insulator transition (MIT) at TMIT~180 K with apparent thermal hysteresis; however, no superlattice peaks or peak splitting below TMIT, which corresponds to a structural transition from Pbnm to P21/n, was observed. The successful growth of NdNiO3 crystals at relatively low temperatures and oxygen pressure provides an alternative approach for preparing single crystals of interesting perovskites such as RNiO3 (R = Sm-Lu) and parent phases of superconducting square planar nickelates.

Tuneable optical diffractive structures from liquid crystalline materials incorporated into periodic polymeric scaffolds

ABSTRACTDiffractive optical elements (DOEs) are micro-structured components used in various photonic devices to manipulate propagation direction and often also polarisation state of optical beams. The simplest type of DOEs are one-dimensional diffraction gratings. We perform theoretical investigation of electrical and magnetic tunability of such gratings composed as a periodic assembly of polymer and ferromagnetic nematic liquid crystal (LC) layers. We analyse how various grating parameters and boundary conditions influence the LC configuration in the assembly. For static response to external electric and/or magnetic fields, the distortion profile of the director field is determined numerically and analytically by minimisation of the Landau-de Gennes free energy, while for the dynamic response only numerical solutions are provided. The resulting optical diffraction properties are determined numerically via solving the Maxwell’s equations by using the rigorous coupled-wave analysis. We demonstrate that the described methodology provides an efficient tool for designing various new types of polarisation-sensitive LC-based DOEs, such as three-state polarisation switches for application in spectroscopic, optical communication, and remote sensing systems.

Analytical Research on the Mitigation of Structure-Borne Vibrations from Subways Using Locally Resonant Periodic Foundations

Filtering properties of locally resonant periodic foundations (LRPFs) have inspired an innovative direction towards the mitigation of structural vibrations. To mitigate the structure-borne vibrations from subways, this study proposes an LRPF equipped with a negative stiffness device connecting the resonator and primary structure. The proposed LRPF can exhibit a quasi-static band gap covering the ultra-low frequency range. These frequency components have the properties of strong diffraction and low attenuation and contribute the most to the incident wave fields impinging on nearby buildings. By formulating the interaction problem between the tunnel-ground and LRPF-superstructure systems, the mitigation performance of the proposed LRPF is evaluated considering the effects of soil compliance and superstructure. The performance depends on the dynamic properties of the ground, foundation, and superstructure as well as their coupling. Transmission analyses indicate that the superstructure responses can be effectively attenuated in the quasi-static band gap by adjusting the negative stiffness. Considering the coupling of the flexible ground, the peak responses of the LRPF-superstructure system occur not only at its eigenfrequencies but also at coupled resonance frequencies due to the contribution of the soil compliance. This study provides an analytical tool for mitigating the structure-borne vibrations from subways with the LRPF.

A (NiMnCo)-Metal-Organic Framework (MOF) as active material for Lithium-ion battery electrodes

A (NiMnCo)-Metal-Organic Framework and its oxidized and pyrolysed derivatives have been tested as electrode materials for lithium-ion batteries. Materials have been fully characterized by Scanning Electron Microscopy (SEM), powder X-Ray Diffraction (XRD), Thermogravimetric Analyses (TGA), Infrared (IR) spectroscopy and electrochemical properties have been determined in coin cells using lithium metal as the counter electrode. Studies have revealed specific capacities of 860 mAh g−1 and 800 mAh g−1 at 15 mA g−1 respectively for the MOF and the oxide (690 and 190 mAh g−1 after 50 cycles) whereas the corresponding pyrolysed compound has shown limited electrochemical performances. Ex situ XRD has been performed to highlight the evolution of the material structure during cycling. These results show that electrochemical storage is based on a conversion reaction.

Preparation and Characterization of Stellera Chamaejasme-Based Carbon Molecular Sieves

The activation effect of boric acid as an activator is good, and we investigate the best activation conditions for the boric acid impregnation method. To represent the structural characteristics and adsorption performance of the Stellera Chamaejasme based carbon molecular sieves, we use Brunner-Emmet-Teller (BET) measurements, scanning electron microscope (SEM), Raman spectra (Raman), X-ray diffraction (XRD), and adsorption property measurement. When the loading ratio was 0.68:1, the specific surface area was 532.21 m2/g, the total pore volume was 0.24 cm3/g, the average pore size was 1.81 nm, the adsorption value of methylene blue was 145.28 mg/g, and the adsorption value of iodine was 713.33 mg/g, the results showed that boric acid had better activation effect. The carbon molecular sieves made from Stellera Chamaejasme and activated with boric acid produce two peaks on the aperture distribution graph that are densely distributed in the micropore range. This indicates that boric acid’s pore-forming tendency is primarily micropore.

Far and near fields of Hermite–Gaussian beams passing through an annular aperture and its numerical simulation by the angular spectrum method

This research focuses on the analysis of the free propagation of Hermite–Gaussian beams diffracted by a symmetrical annular aperture placed at the beam waist plane. The propagation is studied analytically and numerically using the angular spectrum method and the 2D fast Fourier transformation. Numerical simulation examples illustrate the propagation characteristics of the Hermite–Gaussian beams diffracted by an annular aperture. The beam truncation parameters and obscuration ratio influence Hermite–Gaussian beam diffraction properties.

FABRICATION OF ZINC OXIDE NANOPARTICLES BY CHEMICAL AND BIOLOGICAL METHODS

In the current study, nanoparticles (NPs) of zinc oxide (ZnO) were prepared followed by determination of their characters among chemical and biological tools. In aqueous media from zinc acetate dihydrate and sodium hydroxide ZnONPs were fabricated by a precipitation method. To characterize the physicochemical properties of ZnO NPs transmission electron microscopy (TEM) and X-ray diffraction (XRD) were applied. The chemically fabricated ZnONPs (cZnO NPs) characterized with by crystalline structure with hexagonal structure of the wurtzite. The morphology of cZnO NPs was spherical with a primary size of 5-30 nm. Aqueous leaves extract of Ocimum sanctum was used for biological preparation, which may be more ecofriendly and economical compared to other commonly used methods. Results of XRD patterns confirmed the crystalline nature of biologically fabricated ZnONPs (bZnO NPs). Electron micrographs revealed that the resultant bZnO NPs characterized by a spherical shape and a particle size ranged from 8.92 to 37.9nm.The results revealed the crystalline nature of biologically produced ZnO NPs (bZnO NPs). Electron micrographs of the fabricated ZnO NPs also were identified with spherical shape and a particle size distribution of 8.92-37.9 nm.

Simulated LCSLM with Inducible Diffractive Theory to Display Super-Gaussian Arrays Applying the Transport-of-Intensity Equation

We simulate a liquid crystal spatial light modulator (LCSLM), previously validated by Fraunhofer diffraction to observe super-Gaussian periodic profiles and analyze the wavefront of optical surfaces applying the transport-of-intensity equation (TIE). The LCSLM represents an alternative to the Ronchi Rulings, allowing to avoid all the related issues regarding diffractive and refractive properties, and noise. To this aim, we developed and numerically simulated a LCSLM resembling a fractal from a generating base. Such a base is constituted by an active square (values equal to one) and surrounded by eight switched-off pixels (zero-valued). We replicate the base in order to form 1 ×N-pixels and the successive rows to build the 1024×1024 LCSLM of active pixels. We visually test the LCSLM with calibration images as a diffractive object that is mathematically inducible, using mathematical induction over the N×N-shape (1×1, 2×2, 3×3, …, n×n pixels for the generalization). Finally, we experimentally generate periodic super-Gaussian profiles to be visualized in the LCSLM (transmission SLM, 1024×768-pixels LC 2012 Translucent SLM), modifying the TIE as an optical test in order to analyze the optical elements by comparing the results with ZYGO/APEX.

Metasurface for polarization-independent asymmetric transmission of diffraction property using mixed cavity-aperture array

Asymmetric optical systems have been actively researched in various applications in terms of products and services in optical communication and diffractive optics technologies. Among the various methods for achieving optical asymmetry, using metasurfaces are quite suitable because of their high-compactness. In this paper, a polarization-independent metasurface for asymmetric optical diffraction is proposed by using a checkerboard pattern of two-types of nanohole structures. The key principle for asymmetric optical diffraction is an optimal design of effective optical period, which can be achieved by tuning the cavity-aperture geometry. The proposed structure shows asymmetric diffraction properties without complicated multilayer structure. We expect that the proposed asymmetric diffractive metasurface has great potential for polarization-independent miniaturized asymmetric optical diffraction systems or asymmetric Janus holographic imaging in the near-infrared region.