X-ray Diffraction Experiments Research Articles

New Route to Synthesize High-Entropy Carbide Powders by Mechanical Alloying

A new route for the synthesis of the (NbTa)0.67\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{0.67}$$\\end{document}(TiHfZr)0.33\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{0.33}$$\\end{document}C and (NbTa)0.67\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{0.67}$$\\end{document}(MoHfW)0.33\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{0.33}$$\\end{document}C high-entropy carbides powders by mechanical alloying is presented. Namely, pure metal powders were wet-milled in toluene using a planetary mill under an argon atmosphere. The synthesized materials crystallize with a rock-salt structure (space group Fm3¯m\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$Fm{\\bar{3}}m$$\\end{document}). A significant reduction in structural defects with annealing of the samples was detected with X-ray diffraction and positron annihilation experiments. Simultaneously, only simple metallic properties without any trace of magnetic or superconducting phase transitions were observed.

Pore Structure and Fractal Characteristics of Coal Measure Shale in the Wuxiang Block in the Qinshui Basin

To study the fractal characteristics of the pore structure and the main controlling factors of coal measure shale in the Wuxiang block in Qinshui Basin, gas adsorption (CO2 and N2), mercury intrusion porosimetry (MIP), total organic carbon (TOC) content, and X-ray diffraction (XRD) experiments were carried out. The fractal dimensions of the micropores, mesopores, and macropores were computed by combining the V-S, FHH, and MENGER models. The results show that the fractal dimension increases with the increase in pore size; so, the macropore structure is the most complex. The effects of the TOC content, mineral fractions, and pore structure on the fractal dimensions were analyzed. The results showed that the TOC content certainly correlated with the mesopore fractal dimension, and the R2 is 0.9926. The pore volume and specific surface area show an obvious positive correlation with the macroporous fractal dimension, and their R2 values are 0.6953 and 0.6482, indicating that the macroporous pore structure of coal shale in the study area is more complex. There is a significant positive correlation between kaolinite and the macropore fractal dimension, and the R2 is 0.7295. Therefore, the organic carbon and kaolinite contents and the pore structure parameters are the most important factors affecting the fractal dimension characteristics.

Synthesis, crystal structure and optical properties of the first Hg-based polyselenide Ba2HgSe5

A new polyselenide, Ba2HgSe5 has been synthesized via conventional high-temperature solid state reaction. Single-crystal X-ray diffraction experiment reveals that the title compound crystallizes in the centrosymmetric space group Pnma of the orthorhombic system with a = 12.7123(7) Å, b = 8.9593(5) Å, c = 8.5470(5) Å and Z = 4. Its crystal structure consists of isolated dumbbell-shaped (HgSe2)2- and V-shaped Se32− ions. These molecular anions are charge-balanced by Ba2+. Diffuse reflectance spectrum demonstrates the semiconducting properties with a direct band gap of 1.75 eV. Electronic band structure calculation indicates that the band gap is defined by the 4p-orbitals of the selenium atoms of the Se32− groups. Moreover, the photocatalytic behavior of the polycrystalline sample was investigated by decomposing antibiotics tetracycline hydrochloride under visible right irradiation and the result indicates that the title compound displays moderate degradation rate of 60 % within 2 h. In addition, thermal analysis shows that Ba2HgSe5 has a good thermal stability up to 640 °C and exhibits incongruent melting behavior. These characteristics imply that Ba2HgSe5 may be a fascinating photoelectronic material and has potential applications in the future.

Phase Formation Mechanism and Piezoelectric Behaviour of NaNbO3 Ceramic

The solid state reaction route is adopted to synthesize NaNbO3 with the aim to examine their structural, morphological and electrical behaviour of material with sintering time. The crystal phase is formed without any secondary phase at calcination temperature 800 °C. The article shows the scope of material to be used as a sensor in piezoelectric applications. The synthesized material has been avoided to heat for longer time and has been sintered at 2 h, 4 h and 6 h. The refinement of experimental X-ray diffraction pattern displays crystallization of material in Orthorhombic phase with space group Pbcm and lattice parameters a = 5.513752 Å, b = 5.568852 Å, c = 15.52854 Å, α = β = γ = 90°. A gaussian distribution of grain size with statistical average 0.722 μm, 0.841 μm and 0.842 μm has been observed for NN02, NN04 and NN06 respectively. The NN04 shows maximum piezoelectric coefficient d33* = 110 pm V−1, piezoelectric strain 0.0021% and smallest as asymmetric factor Ys = 0.204 with respect to other investigated samples.

In-situ X-ray diffraction study of Nb-doped Bi2Se3 crystal growth revealing unavoidable misfit layer compound

Temperature-resolved in-situ powder X-ray diffraction (PXRD) experiments were performed during synthesis of Nb-doped Bi2Se3 to gain important insights into the phase formation. The crystallization of phases upon heating the pure elements with the nominal composition of Nb0.25Bi2Se3, displays the formation of a misfit layer compound, (BiSe)1.1NbSe2, as a secondary phase. It was also discovered that a misfit-related intermediate phase appears right before Bi2Se3 melts and then misfit (BiSe)1.1NbSe2 crystallizes. This implies that to prevent the formation of the misfit phase, the synthesis temperature should remain well below the melting point of Bi2Se3. Powder samples of Nb-doped Bi2Se3, synthesized at 600 and 650∘C, aimed for this, however, they all displayed traces of the misfit phase. Additionally, multiple superconducting transitions were observed as non-quenched samples showed signs of NbSe2, which were removed by quenching the samples. This study has important implications for the synthesis and properties of Nb-doped Bi2Se3, towards the realization of topological superconductors.

Study on instability mechanism of soft rock roadway and pressure-relief bolt-grouting support technology

Aiming at the engineering problem of roadway deformation and instability of swelling soft rock widely existed in Kailuan mining area, the mineral composition and microstructure of such soft rock were obtained by conducting scanning electron microscopy, X-ray diffraction experiments, uniaxial and conventional triaxial tests, and the law of softening and expanding of such soft rock and the failure mechanism of surrounding rock were identified. The combined support scheme of multi-level anchor bolt, bottom corner pressure relief and fractional grouting is proposed. The roadway supporting parameters are adjusted and optimized by FLAC3D numerical simulation, and three supporting methods of multi-layer anchor bolt, bottom corner pressure relief and fractional grouting are determined and their parameters are optimized. The study results show that: the total amount of clay minerals is 53–75%, pores, fissures, nanoscale and micron layer gaps are developed, providing a penetrating channel for water infiltration to soften the surrounding rock; the three-level anchor pressure-relief and grouting support technology can control the sinking amount of the roof within 170 mm, the bottom drum amount within 210 mm, the bolts of each level is evenly distributed in tension, and the maximum stress and bottom drum displacement in the pressure relief area are significantly reduced; the pressure-relief groove promotes the development of bottom corner cracks, accelerates the secondary distribution of peripheral stress, and weakens the effect of high stress on the shallow area. Using time or displacement as the index, optimizing the grouting time, filling the primary and excavation cracks, blocking the expansion and softening effect of water on the rock mass, realizing the dynamic unity of structural yielding pressure and surrounding rock modification, has guiding significance for the support control of soft rock roadway.

Xylarcurcosides A-C, three novel isopimarane-type diterpene glycosides from Xylaria curta YSJ-5

Three previously undescribed isopimarane-type diterpene glycosides named as xylarcurcosides A-C (1–3) along with two known ones 16-α-d-mannopyranosyloxyisopimar-7-en-19-oic acid (4) and hypoxylonoid A (5) were successfully isolated from an ethyl acetate extract of the endophytic fungus Xylaria curta YSJ-5 growing in leaves of Alpinia zerumbet. The spectroscopic methods, electronic circular dichroism (ECD) calculations, and X-ray diffraction experiments were conducted to identify their absolute chemical structures. All these compounds were tested for in vitro cytotoxic, anti-inflammatory, α-glucosidase inhibitory, and antibacterial activities. As a result, these novel compounds demonstrated no obvious cytotoxic and antibacterial activity.

Acetylacetonate Ruthenium Nitrosyls: A Gateway to Nitric Oxide Release in Water under Near-Infrared Excitation by Two-Photon Absorption.

A fundamental challenge for phototriggered therapies is to obtain robust molecular frameworks that can withstand biological media. Photoactivatable nitric oxide (NO) releasing molecules (photoNORMs) based on ruthenium nitrosyl (RuNO) complexes are among the most studied systems due to several appealing features that make them attractive for therapeutic applications. Nevertheless, the propensity of the NO ligand to be attacked by nucleophiles frequently manifests as significant instability in water for this class of photoNORMs. Our approach to overcome this limitation involved enhancing the Ru-NO π-backbonding to lower the electrophilicity at the NO by replacing the commonly employed 2,2'-bipyridine (bpy) ligand by an anionic, electron-rich, acetylacetonate (acac). A versatile and convenient synthetic route is developed and applied for the preparation of a large library of RuNO photoNORMs with the general formula [RuNO(tpy)(acac)]2+ (tpy = 2,2':6',2″-terpyridine). A combined theoretical and experimental analysis of the Ru-NO bonding in these complexes is presented, supported by extensive single-crystal X-ray diffraction experiments and by topological analyses of the electron charge density by DFT. The enhanced π-back-bonding, systematically evidenced by several techniques, resulted in a remarkable stability in water for these complexes, where significant NO release efficiencies were recorded. We finally demonstrate the possibility of obtaining sophisticated water-stable multipolar NO-delivery platforms that can be activated in the near-IR region by two-photon absorption (TPA), as demonstrated for an octupolar complex with a TPA cross section of 1530 GM at λ = 800 nm and for which NO photorelease was demonstrated under TPA irradiation in aqueous media.

Salvia officinalis-Hydroxyapatite Nanocomposites with Antibacterial Properties.

In the present study, sage-coated zinc-doped hydroxyapatite was incorporated into a dextran matrix (7ZnHAp-SD), and its physico-chemical and antimicrobial activities were investigated. A 7ZnHAp-SD nanocomposite suspension was obtained using the co-precipitation method. The stability of the nanocomposite suspension was evaluated using ultrasound measurements. The stability parameter calculated relative to double-distilled water as a reference fluid highlights the very good stability of the 7ZnHAp-SD suspension. X-ray diffraction (XRD) experiments were performed to evaluate the characteristic diffraction peak of the hydroxyapatite phase. Valuable information regarding the morphology and chemical composition of 7ZnHAp-SD was obtained via scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) studies. Fourier-transform infrared spectroscopy (FTIR) measurements were performed on the 7ZnHAp-SD suspensions in order to evaluate the functional groups present in the sample. Preliminary studies on the antimicrobial activity of 7ZnHAp-SD suspensions against the standard strains of Staphylococcus aureus 25923 ATCC, Enterococcus faecalis 29212 ATCC, Escherichia coli 25922 ATCC, and Pseudomonas aeruginosa 27853 ATCC were conducted. More than that, preliminary studies on the biocompatibility of 7ZnHAp-SD were conducted using human cervical adenocarcinoma (HeLa) cells, and their results emphasized that the 7ZnHAp-SD sample did not exhibit a toxic effect and did not induce any noticeable changes in the morphological characteristics of HeLa cells. These preliminary results showed that these nanoparticles could be possible candidates for biomedical/antimicrobial applications.

Degradation mechanism and evaluation of the carbonation resistance of concrete after high-temperature exposure

High-temperature exposure during fire decreases not only the mechanical properties of concrete structures but also their durability, especially their concrete carbonation resistance. However, the degradation of concrete carbonation resistance after fire exposure remains unclear. Concrete specimens with water/cement (w/c) ratios of 0.4, 0.5, and 0.6 were fabricated to solve such problems, and high-temperature experiments were performed at 400 °C, 500 °C, and 600 °C and sustained for one hour. Then, mechanical and accelerated carbonation experiments were conducted, and the carbonation depths and pH values of concrete were tested. X-ray diffraction, thermogravimetry analysis, and mercury intrusion porosimetry experiments were also performed on concrete with and without high-temperature treatment. Results showed that high-temperature exposure caused severe degradation in concrete compressive strength, relative dynamic modulus of elasticity, and carbonation resistance, and the carbonation resistance loss of concrete was higher than its mechanical property loss. Concrete with lower w/c ratio suffered more losses in mechanical properties, whereas w/c ratio had no obvious effect on the carbonation resistance degradation of fire-damaged concrete. The key mechanism of the decline in the carbonation resistance of concrete after fire was not mainly the alkalinity drop in concrete but the considerable increase in concrete porosity and harmful pores. Instead of the traditional phenolphthalein method, a new method of residual OH- concentration of superficial concrete after accelerated carbonation was proposed to evaluate the carbonation resistance of concrete after fire. The average carbonation resistance of the concrete with the three w/c ratios was reduced by 66.3 %, 84.2 % and 95.1 % after exposure to 400 °C, 500 °C, and 600 °C, respectively.

Characterization of nano-SiO2 cemented soil under the coupled effects of dry-wet cycles and chlorination

In contrast to cemented soils in terrestrial natural environments, cemented soils in littoral and marine geotechnical engineering face numerous difficulties. In coastal and marine geotechnical engineering, cemented soils are frequently degraded by ion erosion, tidal scouring, and temperature variations. Long-term marine environments present numerous challenges for cemented soil foundation projects. In marine geotechnical engineering, addressing and enhancing these degradation issues has become a crucial topic. To address this engineering problem, Nano-SiO2 is added to cement-stabilized soils to enhance their engineering performance. To investigate the mechanical effects and erosion mechanisms of Nano-SiO2 cemented soil subjected to chloride ion erosion and tidal alternation scouring, laboratory experiments, including immersion erosion tests with sodium chloride solution and dry-wet cycle tests, were designed. On specimens subjected to dry-wet cycles after chloride ion erosion at varying concentrations, unconfined compressive strength tests (UCS), X-ray diffraction (XRD) experiments, and scanning electron microscopy (SEM) were performed. The objective was to investigate the impact of chloride ions and Nano-SiO2 on the microstructure and strength of cemented soil. Adding 2.5% Nano-SiO2 can promote cement hydration reactions while preventing the entry of chloride ions into the cemented soil, thereby increasing the density and compressive strength of the cement.

Investigation of the hydrogen bonded host‧‧‧guest and guest‧‧‧guest interactions present in complexes of a polyaromatic wheel-and-axle host compound with dioxane, morpholine, piperidine and pyridine

1,4-Bis(diphenylhydroxymethyl)benzene (H), a host compound possessing wheel-and-axle geometry, was found to possess host ability for dioxane (DIO), morpholine (MOR) and piperidine (PIP), forming inclusion compounds with each one with 1:2 host:guest ratios. This observation prompted an investigation of the host behaviour in mixtures of these guest compounds but where pyridine (PYR) was also considered (PYR was reported earlier to also form a 1:2 complex with H). In mixtures, H demonstrated significant affinities for, more especially, MOR and PIP, while DIO and PYR were usually disfavoured guest species. Single crystal X-ray diffraction experiments revealed that MOR (a favoured guest species) interacted by means of three hydrogen bonds with both adjacent guest and host molecules, plausibly explaining the host preference for this guest species; each of DIO, PYR and PIP were involved in only one interaction of this type with H. Total energy calculations revealed that the host-guest molecular pairs involving preferred MOR and PIP possessed significantly lower energies than those with disfavoured DIO and PYR. Thermal analyses demonstrated that the complex containing the least favoured guest compound, H‧2(DIO), possessed the lowest thermal stability of the four complexes, but these experiments did not clearly explain the affinity of H for MOR.

Thermal and structural behavior of mango (Mangifera indica L) kernel fat from three Ivorian varieties

AbstractMango (Mangifera indica L.) seeds is an interesting source of fat, rich in stearic (St) and oleic (O) acid with three major triacylglycerols (TAG): StOSt, StOO, and StLSt. The kernel fat content and quality depend however on the varieties and their origin. The objective of this study was to investigate the crystallization and polymorphic behavior of mango kernel fat extracted from three selected Ivorian varieties which differ in terms of TAG composition: Kent (KT), Djakoumankoun (DN) and Brooks (BR). The isothermal crystallization behavior was examined at 15 and 20°C by pulsed nuclear magnetic resonance, differential scanning calorimetry, x‐ray diffraction (XRD) and polarized light microscope. Under static conditions, DN crystallized faster, followed by BR, then KT. At 15°C, an unusual evolution was observed for both DN and BR, which can be explained by a melt‐mediated polymorphic transition from α into more stable forms. Using a differential scanning calorimetry (DSC) stop‐and‐return technique, different crystallization behaviors were also observed. Isothermal XRD experiments confirmed that the kinetics of the polymorphic transformation was different within the three samples, even if the three fats were β‐3L‐tending. At 15°C, KT transformed from liquid state to stable form without passing through α‐form, while DN and BR crystallized first into α‐from which transformed further to β′, then into stable β‐form. At 20°C, DN and BR crystallized directly from liquid to β′, which later transformed into β‐form while KT did not crystallize under the same conditions. The huge differences observed result from the differences in the TAG profiles, mainly in the StOO and StOSt content.

Synthesis, structural study, and Na+ migration pathways simulation of the new phase Na3Al3(AsO4)4

Single crystals of the novel arsenate, Na3Al3(AsO4)4 have been isolated and their structure has been determined by X-ray diffraction experiment. Na3Al3(AsO4)4 crystallizes in the monoclinic space group C2/c with a = 19.837(1) Å; b = 6.448(3) Å; c = 10.437(6) Å, β = 91.986 (3)° and Z = 2. The structural model was confirmed by both bond valence sum (BVS), charge distribution (CHARDI) validation tools and density functional theory (DFT) method. The empirical activation energy for sodium migration channels within the crystal structure was estimated by the bond valence site energy landscape (BVSE) map method. With an energy barrier of 0.409 eV, the crystal structure features 3D networks of pathways suitable for Na+ ion migration.

Effect of route production and doping concentration on luminescence response of MgB4O7: Gd phosphor

This work studied the synthesis route and gadolinium (Gd) doping concentration on magnesium tetraborate (MBO) luminescence response. The material was synthesized by solid-state reaction techniques with two different procedures (Routes A and B) for three different Gd concentrations (0.2, 0.3, and 0.7 %wt). Route A consisted of the synthesis of the MBO matrix and subsequently add Gd2O3 as an activator. Route B the material was obtained after mixing and co-milling the precursors and the activator together prior to synthesis. Rietveld refinement of experimental X-ray diffraction data indicates that the MgB4O7:Gd compounds exhibit single phases consistent with orthorhombic symmetry (space group Pbca (61)). These compounds also evidenced contributions Gd dopant concentrations in MgB4O7 matching the cubic symmetry of the material. The electron microscopic scan surface morphological study exhibited the formation of polycrystalline material with diverse grain shapes for the two production routes. Compositional characterization by electron X-ray energy spectroscopy suggested that there were no other elements besides the expected elements in the material. The optical response by diffuse reflectance spectroscopy estimated the energy gap from the fundamental absorption of the undoped host. Optically stimulated luminescence response suggested that MgB4O7:Gd 0.7%wt (route B) sensitivity is 2.1 times higher than that presented in MgB4O7:Gd 0.3 % (route A). Thermoluminescence experiments showed that the optimum Gd dopant concentrations for the most intense dosimetric peak of phosphorus MgB4O7 fabricated using routes A and B were 0.3 % (main peak: 209 °C) and 0.7 % (main peak: 276 °C), respectively. The thermoluminescence sensitivity of MgB4O7:Gd 0.3%wt (route A) is 3.5 times higher than the sensitivity of MgB4O7:Gd 0.7%wt (route B).

Investigation of the high-temperature fatigue mechanism related to altered local short-range order in AL6XN austenitic stainless steel

An increase in crystal local short-range order (SRO), characterized by obvious diffuse intensity maxima at 1/3{422} in the [111]-axis selected area diffraction pattern, is observed in AL6XN austenitic stainless steel subjected to high-temperature low-cycle fatigue deformation. SRO is an ordered fcc structure with nanometer size, which can be well explained by the ordered arrangement of Cr/Mo atomic layers segregated on the {422} crystal plane in austenite. Many planar slip bands are observed in the fatigue sample, the distribution of SROs is highly related with the distribution of dislocations. In situ high-energy X-ray diffraction (HE-XRD) experiments are performed to investigate the deformation behavior of both as-received and fatigued samples under uniaxial loading. The lattice strain evolution reveals an interesting lattice expansion in the initial elastic stage, which provides direct evidence of a decrease in SRO during further uniaxial tensile deformation, indicating that the deformation modes greatly affect the SRO transition. We believe that the high-temperature fatigue damage originates mainly from the accumulation of planar slip bands, accompanied by a local increase in SRO, which promotes work hardening near the final fatigue fracture.

Dual-phase La0.5Sr0.5Fe0.8Co0.2O3−δ-Ce0.8Sm0.2O2-δ hollow fiber membranes for oxygen separation

In this work, the dual-phase La0.5Sr0.5Fe0.8Co0.2O3-δ-Ce0.8Sm0.2O2-δ (LSCF-SDC) (65–35 wt%) hollow fiber membranes were prepared via combined method of phase inversion and sintering technique. In situ X-ray diffraction (XRD) experiments showed that the structure of LSCF-SDC is stable in air and vacuum (pO2 ∼ 10−4 atm) in the temperature range of 30–900 °C. Moreover, the effect of temperature, oxygen partial pressure and surface modification on the oxygen fluxes across LSCF-SDC hollow fiber membranes were studied. The results obtained indicate that the oxygen fluxes through dual-phase LSCF-SDC hollow fiber membranes are limited by surface exchange reactions. LSCF-SDC hollow fiber membranes also demonstrated high resistance to CO2 in short-term stability test.

Investigation of residual stresses and modeling of tensile deformation in wire-arc additive manufactured 6061 aluminum alloy: Diffraction and elastoplastic self-consistent model

The aim of this work is to study the mechanical behavior of 6061 aluminum walls produced by Wire Arc Additive Manufacturing at the different scales of the material. The residual stresses of the parts are characterized on the surface and in the bulk thanks to X-ray and neutron diffraction techniques, respectively. Although the residual stress values determined in the close-surface are low (40 MPa for the maximum value), the mechanical state is different in depth with significant maximum residual stress levels ( ± 100 MPa). Tensile tests carried out on samples extracted from a WAAM wall in three orientations reveal that the mechanical properties of the manufactured material are slightly better compared to conventional material in T6 state. In situ X-ray diffraction experiments have also been performed under uniaxial tensile testing in order to determine strain pole figures. An elasto-plastic self-consistent model considering the microstructural characteristics and the main physical phenomena governing the material behavior, is proposed. The model agrees with the experimental data and the simulations reproduce the main features observed at the scale of the diffracting volume.

Synthesis and optical properties of novel red-emitting phosphors Ba3Lu1–xEuxB9O18 (x = 0–0.85)

The novel red-emitting phosphors Ba3Lu1–xEuxB9O18 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.85) belonging to the Ba3REEB9O18 (REE – Y, Pr–Lu) family were successfully obtained by a multistep solid-phase synthesis. X-ray diffraction experiments revealed no phase transitions caused by the Eu3+ → Lu3+ isomorphic substitution in this series of solid solutions. An increase in the Eu3+ content leads to an expectable increase of hexagonal unit cell parameters and volume. Optical properties of the Ba3Lu1–xEuxB9O18 (x = 0–0.85) phosphors were investigated. The highest emission intensity was demonstrated by Ba3Lu0.6Eu0.4B9O18. The concentration quenching of luminescence was revealed for the x(Eu3+) > 0.4 samples. Concentration quenching, quantum yield and structural data were compared between three red-emitting Ba–Lu borates-phosphors (BLBO:Eu3+) containing independent crystallographic sites for the REE ions (n = 1–3) in crystal structure. It was revealed that the higher the number of nonequivalent cationic REE sites suitable for the Eu3+ → Lu3+ substitution, the higher the quantum yield taking into account practically equal amount of an optimal concentration of the activator-ion. Such an observation could be useful for a crystal chemical design of novel phosphors.

An operando synchrotron study on the effect of wire melting state on solidification microstructures of Inconel 718 in wire-laser directed energy deposition

Directed energy deposition (DED) with a coaxial wire-laser configuration has gained significant attention in recent years for the production of large-scale metallic components because of its low directional dependence, fast deposition rate, high feedstock efficiency, and low manufacturing costs. This work studies the coaxial wire-laser DED process of Inconel 718 alloy under a stable deposition condition with a relatively low input volumetric energy density (55.5 J/mm3). Post characterization reveals a cluster of refined grains at the center-bottom region of the as-printed track. Operando high-energy synchrotron X-ray experiments and multi-physics modeling are applied innovatively to study the fundamental mechanism responsible for the formation of this microstructure. The X-ray diffraction experiment provides direct evidence, which is supported by the simulation, that the feeding wire can reach the melt pool bottom and release solid particles (primarily carbides) near the mushy zone owing to insufficient melting. Consequently, these sub-micron sized particles suppress the growth of large columnar grains and cause the formation of unique microstructural heterogeneity. This discovery offers new opportunities for tailoring the solidification microstructure by controlling the melting state of the feedstock wire in DED process, in addition to commonly known factors such as the thermal gradient and solidification velocity.