Energy Dispersive X-ray Spectroscopy Mapping Research Articles

Preparation and characterization of expanded dickite/decanoic acid phase-change materials

The leakage of phase-change materials presents a significant challenge that impedes their application. Loading porous materials onto phase-change materials is an effective approach to addressing this issue. In this study, porous expanded dickite as a carrier was utilized to load decanoic acid and create a composite phase-change material. The loading content of decanoic acid was varied to obtain different composite phase-change materials. Fourier transform infrared spectroscopy analysis confirmed the formation of hydrogen bonds between the expanded dickite carrier and decanoic acid. Scanning electron microscopy images and energy-dispersive X-ray spectroscopy mapping results demonstrated that decanoic acid was evenly dispersed on the expanded dickite carrier without any agglomeration. The expanded dickite carrier effectively immobilized decanoic acid through hydrogen bonding, thereby preventing leakage, as long as the loading content of decanoic acid did not exceed 60%. The higher thermal conductivity of the expanded dickite carrier promoted the thermal conductivity of the expanded dickite/decanoic acid composite phase-change materials, enhancing the responsiveness of the composite phase-change materials to ambient temperature. The composite phase-change material containing 60 wt% decanoic acid exhibited excellent endothermic/exothermic cycle stability, and after six cycles, its latent heat remained stable.

Effect of molybdenum concentration on mechanical, microstructural, corrosion, and tribological properties of (Al3Ni–Al3Ni2)100-x -Mox (x= 3, 5, and 7 wt%) composites

The nickel aluminide intermetallic is a crucial material for structural components in high-temperature applications. This study investigates the impact of adding Mo at three different concentrations (3, 5, and 7 wt%) to the Al3Ni–Al3Ni2 intermetallic powder produced by mechanical alloying. The composite powders are then consolidated by cold compaction and sintered at a temperature of 800 °C. The resulting Al3Ni–Al3Ni2 intermetallic, Al3Ni–Al3Ni2–Mo3, Al3Ni–Al3Ni2–Mo5, and Al3Ni–Al3Ni2–Mo7 composites are examined for their mechanical, metallurgical, corrosion, and tribological behaviors. The microstructure showed that adding 3 and 5 wt% of Mo to the Al3Ni–Al3Ni2 intermetallic resulted in good metallurgical bonding, less porosity, and grain refinement with a homogeneous distribution. However, the addition of 7 wt% Mo resulted in high porosity with an inhomogeneous distribution. The Al3Ni–Al3Ni2–Mo5 composite showed the highest yield strength (947 MPa), ultimate tensile strength (1365 MPa), and hardness (420.4 HV) due to the dispersion-strengthening effect and grain refinement. On the other hand, the Al3Ni–Al3Ni2–Mo7 composite exhibited lower values than the Al3Ni–Al3Ni2–Mo3 and Al3Ni–Al3Ni2–Mo5 composites due to the inhomogeneous distribution of the Mo elements observed through energy dispersive X-ray spectroscopy (EDS) mapping. The presence of a passive film on the surface of the Al3Ni–Al3Ni2–Mo5 composite resulted in higher corrosion resistance and lower corrosion rate (0.0221 mm/yr) compared to other samples. The wear test results showed that the Al3Ni–Al3Ni2–Mo5 composite exhibits better wear resistance than the other samples due to tribo oxide layers.

Anti-corrosive superhydrophobic coatings for reinforcement protection: recycling of concrete garbage

Purpose The purpose of this paper was to prepare a ternary hierarchical rough particle to accelerate the anti-corrosive design for coastal concrete infrastructures. Design/methodology/approach A kind of micro-nano hydrophobic ternary microparticles was fabricated from SiO2/halloysite nanotubes (HNTs) and recycled concrete powders (RCPs), which was then mixed with sodium silicate and silane to form an inorganic slurry. The slurry was further sprayed on the concrete surface to construct a superhydrophobic coating (SHC). Transmission electron microscopy and energy-dispersive X-ray spectroscopy mappings demonstrate that the nano-sized SiO2 has been grafted on the sub-micron HNTs and then further adhered to the surface of micro-sized RCP, forming a kind of superhydrophobic particles (SiO2/HNTs@RCP) featured of abundant micro-nano hierarchical structures. Findings The SHC surface presents excellent superhydrophobicity with the water contact angle >156°. Electrochemical tests indicate that the corrosion rate of mild steel rebar in coated concrete reduces three-order magnitudes relative to the uncoated one in 3.5% NaCl solution. Water uptake and chloride ion (Cl-) diffusion tests show that the SHC exhibits high H2O and Cl- ions barrier properties thanks to the pore-sealing and water-repellence properties of SiO2/HNTs@RCP particles. Furthermore, the SHC possesses considerable mechanical durability and outstanding self-cleaning ability. Originality/value SHC inhibits water uptake, Cl- diffusion and rebar corrosion of concrete, which will promote the sustainable application of concrete waste in anti-corrosive concrete projects.

Sonochemical synthesis of bioinspired graphene oxide–zinc oxide hydrogel for antibacterial painting on biodegradable polylactide film

Graphene oxide nanosheet (GO) is a multifunctional platform for binding with nanoparticles and stacking with two dimensional substrates. In this study, GO nanosheets were sonochemically decorated with zinc oxide nanoparticles (ZnO) and self-assembled into a hydrogel of GO–ZnO nanocomposite. The GO–ZnO hydrogel structure is a bioinspired approach for preserving graphene-based nanosheets from van der Waals stacking. X-ray diffraction analysis (XRD) showed that the sonochemical synthesis led to the formation of ZnO crystals on GO platforms. High water content (97.2%) of GO–ZnO hydrogel provided good property of ultrasonic dispersibility in water. Ultraviolet-visible spectroscopic analysis (UV–vis) revealed that optical band gap energy of ZnO nanoparticles (∼3.2 eV) GO–ZnO nanosheets (∼2.83 eV). Agar well diffusion tests presented effective antibacterial activities of GO–ZnO hydrogel against gram-negative bacteria (E. coli) and gram-positive bacteria (S. aureus). Especially, GO–ZnO hydrogel was directly used for brush painting on biodegradable polylactide (PLA) thin films. Graphene-based nanosheets with large surface area are key to van der Waals stacking and adhesion of GO–ZnO coating to the PLA substrate. The GO–ZnO/PLA films were characterized using photography, light transmittance spectroscopy, coating stability, scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopic mapping (EDS), antibacterial test and mechanical tensile measurement. Specifically, GO–ZnO coating on PLA substrate exhibited stability in aqueous food simulants for packaging application. GO–ZnO coating inhibited the infectious growth of E. coli biofilm. GO–ZnO/PLA films had strong tensile strength and elastic modulus. As a result, the investigation of antibacterial GO–ZnO hydrogel and GO–ZnO coating on PLA film is fundamental for sustainable development of packaging and biomedical applications.

Strategic decolorization of rose bengal in an aqueous environment using a zinc oxide-loaded reduced graphene oxide photocatalyst

The environmental and health hazards posed by synthetic organic dyes, such as Rose Bengal, have spurred significant concern in recent years. Herein, a novel zinc oxide/reduced graphene oxide (ZnO/rGO)-based photocatalyst is developed and used for the efficient decolorization of RB dye in aqueous solutions. The as-synthesized nanostructured material is characterized using advanced techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) mapping to elucidate its crystalline structure, morphology, and elemental composition. The XRD pattern confirmed the wurtzite crystalline phase structure with an average size of 67.8 nm, while SEM imaging verified the successful incorporation of ZnO nanoparticles into the rGO matrix. Further, the as-prepared material was used as a photocatalyst, which demonstrated remarkable performance in RB dye decolorization, achieving ≥96.1 % degradation within just 5 min at a minimal catalyst dosage of 8.0 mg. Moreover, kinetic studies revealed that the decolorization process followed a pseudo-second-order reaction mechanism, further enhancing the understanding of the catalytic behavior. It is more interesting that the catalyst exhibited exceptional reusability for up to seven cycles with only a decrease in catalyst efficiency from 96.1 % to 77.5 %, underscoring its practical viability and sustainability. The significance of this work lies in its contribution to addressing the environmental challenges associated with synthetic dyes, particularly rose bengal, by offering an efficient and reliable photocatalytic solution. The demonstrated efficacy of the ZnO/rGO photocatalyst not only showcases its potential for large-scale rose bengal dye degradation but also suggests broader applicability for the treatment of other synthetic dye pollutants.

One-step formation of ZrON thin film on surface of carbon fine particles for membrane electrode assembly

Zirconium nitride and oxynitride films were deposited on alumina or carbon particles by reactive sputtering using a magnetron sputtering apparatus with a Zr hollow cylindrical target and a vibrating equipment with heating capability. The vibrating equipment developed in this study was effective if the particles are spherical and highly monodisperse. Uniform film deposition was achieved over the entire surface of highly monodisperse spherical alumina particles using the vibrating equipment during deposition. Pure ZrN crystalline layers was deposited under Ar and N2 gas flows with heating on XC-72 carbon powder particles removed adsorbed oxygen. Energy dispersive x-ray spectroscopy mapping analysis for deposited XC-72 carbon particles showed ubiquitous film deposition on agglomerated particles regardless of vibration during sputtering. Uniform film deposition with vibrating equipment was achieved on the entire surface of CGB-10 particles with more spherical and monodisperse than XC-72 but precipitated crystalline phase depended on unintentional oxygen chemisorbed on the particles. Addition and increase in flow rate of oxygen to the sputtering gas resulted in the formation of desired crystalline phase, Zr2ON2, Zr7O8N4, and monoclinic ZrO2, precipitated in the film using CGB-10 particles with chemisorbed oxygen removed. Current density for oxygen reduction reaction measured for MEA made from CGB-10 particles with ZrON-based crystals deposited was larger than that for thin film deposited on a carbon plate substrate.

Design and Analysis of Composite Biomaterial Bone Graft Plate

The mixing technique was applied in this study to enhance the strength performance of the cement. The addition of 3% by weight of hydroxyapatite (HA) nanoparticles were mixed with 97% polymethyl methacrylate (PMMA) acrylic polymer, which has a nano size to serve as the matrix material. The surface roughness and continuous porosity of the bone cement were found to be slightly increased by the incorporation of nanoparticles, which enhanced bone-implant osseointegration and ingrowth. Atomic force microscopy (AFM) analysis revealed that the addition of hydroxyapatite (HAp) nanoparticles resulted in a surface roughness value (Sa) of 16.25 nm, which is similar to that of natural bone. The energy-dispersive X-ray spectroscopy (EDS) mapping results discover precentor material and uniform distribution. The Sample exhibited promising results in the antibacterial test, showing efficacy against bacteria both with and without sterilization, confirming its antibacterial properties. The mechanical tests conducted on the sample, including tensile, compression, bending and Vickers hardness tests, yielded favorable results and indicated that the sample is suitable for its intended application. In the theoretical works the design of the bone, screw, and bone plate was conducted using SolidWorks, followed by an analysis using ANSYS under both axial and bending load conditions. The theoretical analysis revealed that the safety factor was less than 1 when an axial load of 13 N was applied and a bending load of 2 N was applied, indicating that the structure may not be able to withstand these loads safely. Under both ambient and physiologically relevant conditions in the human body, HA and PMMA have demonstrated to be excellent choices for enhancing the clinical performance of bone cement. This, in turn, can lead to increased longevity of implants, decreased patient risk, and lower healthcare costs

NASICON-structure Na3+xMnVxTi1-x(PO4)3/C cathode for sodium-ion battery with excellent cycling performance and high specific capacity

The recently discovered Na3MnTi(PO4)3 cathode material has an extremely high theoretical capacity, but its poor cycling performance makes it challenging to apply. In this work, a series of NASICON-type Na3+xMnVxTi1-x(PO4)3/C (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.8, 1) cathode materials were prepared by sol-gel method for sodium-ion batteries. X-ray diffraction (XRD) indicates that vanadium doping has increased the cell spacing within the material and the cell volume. From the results of X-ray photoelectron spectroscopy (XPS) and Energy dispersive X-ray spectroscopy (EDS) mapping images, it is shown that vanadium has been successfully doped into the material. Among them, the Na3·3MnV0·3Ti0·7(PO4)3/C delivers an outstanding specific capacity (121.7 mAh g−1 at 0.1C, C = 135 mA g−1) and Na3·4MnV0·4Ti0·6(PO4)3/C shows an excellent capacity retention (80.88 % after 1500 cycles at 1C). Notably, the coulombic efficiency of both materials during cycling is close to 100 %, indicating that these materials have great practical application value.

Synergistic photocatalytic degradation of crystal violet dye using novel medical waste-derived carbon/ZnO composite: A study on toxicological assessment

The discharge of crystal violet (CV) dye effluents from textile sectors is a significant concern, as these pollutants not only diminish the aesthetic appeal of water bodies but also impede light penetration, thereby disrupting aquatic ecology. Additionally, the COVID-19 pandemic has led to increased usage of disposable face masks, further contributing to medical waste in the environment. In this state-of-the-art study, the aim was to develop a photocatalyst material using medical-waste-derived carbon (MWC) as a support matrix for zinc oxide (ZnO) nanoparticles, facilitating the photocatalytic degradation of CV dye via persulfate (PS) activation. X-ray diffraction and Raman spectroscopy were used to analyze the crystalline and chemical bonding properties of the synthesized photocatalysts, whilst field-emission scanning electron microscopy and transmission electron microscopy with energy-dispersive X-ray spectroscopy mapping were employed to examine the samples’ surface morphology and composition. The UV–vis spectroscopy and photoluminescence spectroscopy were used to confirm the optical properties of the photocatalysts. The degradation analyses showed that the MWC/ZnO nanocomposite achieved a higher degradation efficiency of 94.4%, with a reusability performance of 91.0% in the fifth cycle. Toxicology assessment was performed using seedling Vigna mungo plants and zebrafish, which revealed significant developmental deformities in the embryos and adults of zebrafish treated with the CV solution, but not when grown with the degraded CV solution or water, supporting the non-toxic nature of the degraded dye water. Therefore, the proposed MWC/ZnO nanocomposite could be suggested as a potential catalyst for CV dye degradation and an ideal solution for both aquatic and medical waste pollutants.

Investigation of the Effectiveness of Silicon Nitride as a Reinforcement Agent for Polyethylene Terephthalate Glycol in Material Extrusion 3D Printing.

Polyethylene terephthalate glycol (PETG) and silicon nitride (Si3N4) were combined to create five composite materials with Si3N4 loadings ranging from 2.0 wt.% to 10.0 wt.%. The goal was to improve the mechanical properties of PETG in material extrusion (MEX) additive manufacturing (AM) and assess the effectiveness of Si3N4 as a reinforcing agent for this particular polymer. The process began with the production of filaments, which were subsequently fed into a 3D printer to create various specimens. The specimens were manufactured according to international standards to ensure their suitability for various tests. The thermal, rheological, mechanical, electrical, and morphological properties of the prepared samples were evaluated. The mechanical performance investigations performed included tensile, flexural, Charpy impact, and microhardness tests. Scanning electron microscopy and energy-dispersive X-ray spectroscopy mapping were performed to investigate the structures and morphologies of the samples, respectively. Among all the composites tested, the PETG/6.0 wt.% Si3N4 showed the greatest improvement in mechanical properties (with a 24.5% increase in tensile strength compared to unfilled PETG polymer), indicating its potential for use in MEX 3D printing when enhanced mechanical performance is required from the PETG polymer.

Recovery of Ni-Co-Mn Oxides from End-of-Life Lithium-Ion Batteries for the Application of a Negative Temperature Coefficient Sensor

This study demonstrates the current advancements in battery management systems (BMSs), emphasizing the need for precise temperature monitoring within battery packs to enhance safety and performance through efficient thermal management. The increased demand for lithium-ion batteries (LIBs) has driven the development of temperature sensors with improved accuracy and stability. In particular, Ni-Co-Mn-based spinel oxides are commonly used due to their stable negative temperature coefficient (NTC) behavior. However, challenges arise in manufacturing due to the high cost and uncertain supply of critical cathode components (e.g., Co, Ni, and Mn) for LIBs. This research focuses on developing spinel-type (Ni0.6Co0.4Mn2)O4 using recycled Ni-Co-Mn oxides obtained from end-of-life (EOL) LIBs, demonstrating temperature resistance behavior suitable for temperature sensing. The oxides are prepared through hydrometallurgy, oxalate synthesis, and post-heat treatment. Successful integration into spinel-type NTC thermistors suggests broader applications in various industrial fields. A systematic investigation into the synthesis and characterization of recovered Ni-Co-Mn oxides from EOL LIB cathode materials (Li(Ni0.33Co0.33Mn0.33)O2) is presented for NTC thermistor application. Thermogravimetric analysis-derivative thermogravimetry (TGA-DTG) identifies the optimal post-heat treatment temperature. The X-ray diffraction (XRD) patterns confirm a cubic spinel structure of the Ni-Co-Mn oxides, supported by scanning electron microscope (SEM) images showing a uniform microstructure. Also, energy dispersive X-ray spectroscopy (EDS) mapping confirms homogeneous element distribution. Recovered oxide pellets from the sintering process exhibit a single spinel structure, with X-ray photoelectron spectroscopy (XPS) analysis revealing changes in the valence states for Ni and Mn. Resistivity measurements demonstrate semiconductive behavior, which shows a B value (3376.92 K) suitable for NTC thermistor applications. This study contributes valuable insights to black powder recycling from EOL LIBs and its potential in temperature-sensitive electronic devices.

Tunable Narrow-Band Cyan-Emission of Eu2+-doped Nitridomagnesophosphates Ba3-xSrx[Mg2P10N20] : Eu2+ (x=0-3).

Tetrahedron-based nitrides offer a wide range of properties and applications. Highly condensed nitridophosphates are examples of nitrides that exhibit fascinating luminescence properties when doped with Eu2+, making them appealing for industrial applications. Here, we present the first nitridomagnesophosphate solid solution series Ba3-xSrx[Mg2P10N20] : Eu2+ (x=0-3), synthesized by a high-pressure high-temperature approach using the multianvil technique (3 GPa, 1400 °C). Starting from the binary nitrides P3N5 and Mg3N2 and the respective alkaline earth azides, we incorporate Mg into the P/N framework to increase the degree of condensation κ to 0.6, the highest observed value for alkaline earth nitridophosphates. The crystal structure was elucidated by single-crystal X-ray diffraction, powder X-ray diffraction, energy-dispersive X-ray spectroscopy (EDX), and solid-state NMR. DFT calculations were performed on the title compounds and other related highly condensed nitridophosphates to investigate the influence of Mg in the P/N network. Eu2+-doped samples of the solid solution series show a tunable narrow-band emission from cyan to green (492-515 nm), which is attributed to the preferred doping of a single crystallographic site. Experimental confirmation of this assumption was provided by overdoping experiments and STEM-HAADF studies on the series as well on the stoichiometric compound Ba2Eu[Mg2P10N20] with additional atomic resolution energy-dispersive X-ray spectroscopy (EDX) mapping.

Non-negative matrix factorization-aided phase unmixing and trace element quantification of STEM-EDXS data

Energy-dispersive X-ray spectroscopy (EDXS) mapping with a scanning transmission electron microscope (STEM) is commonly used for chemical characterization of materials. However, STEM-EDXS quantification becomes challenging when the phases constituting the sample under investigation share common elements and overlap spatially. In this paper, we present a methodology to identify, segment, and unmix phases with a substantial spectral and spatial overlap in a semi-automated fashion through combining non-negative matrix factorization with a priori knowledge of the sample. We illustrate the methodology using a sample taken from an electron beam-sensitive mineral assemblage representing Earth's deep mantle. With it, we retrieve the true EDX spectra of the constituent phases and their corresponding phase abundance maps. It further enables us to achieve a reliable quantification for trace elements having concentration levels of ∼100 ppm. Our approach can be adapted to aid the analysis of many materials systems that produce STEM-EDXS datasets having phase overlap and/or limited signal-to-noise ratio (SNR) in spatially-integrated spectra.

Impact of varied zeolite materials on nickel catalysts in CO2 methanation

Ni catalysts supported on 4A, 5A, 13X, ZSM-5, and BEA zeolites were prepared using the vacuum-heating method for CO2 methanation. These support materials play a pivotal role in shaping the catalysts' properties and their catalytic performance. High-resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and energy-dispersive X-ray spectroscopy (EDS) mappings suggest a significant concentration of Ni nanoparticles situated on the external surfaces of catalysts with low Si/Al ratios zeolites (Ni-4A, Ni-5A, and Ni-13X). These Ni nanoparticles exhibit characteristics of weaker metal-support interaction, lower metal reduction temperatures, and moderate H2 adsorption activity. Moreover, these low Si/Al ratio zeolites demonstrate robust CO2 adsorption activity. These properties endow Ni-5A and Ni-13X catalysts with heightened CO2 conversion (70.4–70.9%) and methane selectivity (92.4–96.4%). In contrast, high Si/Al ratio zeolite-based catalysts (Ni-ZSM-5 and Ni-BEA) exhibit smaller Ni particles, strong metal-support interaction and weaker CO2 adsorption activity, resulting in reduced CO2 methanation activity and decreased methane selectivity (71.2–73.4%). The normalized CO2 conversion rate presents a correlation with the average Ni particle size.

Monitoring the Electrochemical Failure of Indium Tin Oxide Electrodes via Operando Ellipsometry Complemented by Electron Microscopy and Spectroscopy.

Transparent conductive oxides such as indium tin oxide (ITO) are standards for thin film electrodes, providing a synergy of high optical transparency and electrical conductivity. In an electrolytic environment, the determination of an inert electrochemical potential window is crucial to maintain a stable material performance during device operation. We introduce operando ellipsometry, combining cyclic voltammetry (CV) with spectroscopic ellipsometry, as a versatile tool to monitor the evolution of both complete optical (i.e., complex refractive index) and electrical properties under wet electrochemical operational conditions. In particular, we trace the degradation of ITO electrodes caused by electrochemical reduction in a pH-neutral, water-based electrolyte environment during electrochemical cycling. With the onset of hydrogen evolution at negative bias voltages, indium and tin are irreversibly reduced to the metallic state, causing an advancing darkening, i.e., a gradual loss of transparency, with every CV cycle, while the conductivity is mostly conserved over multiple CV cycles. Post-operando analysis reveals the reductive (loss of oxygen) formation of metallic nanodroplets on the surface. The reductive disruption of the ITO electrode happens at the solid-liquid interface and proceeds gradually from the surface to the bottom of the layer, which is evidenced by cross-sectional transmission electron microscopy imaging and complemented by energy-dispersive X-ray spectroscopy mapping. As long as a continuous part of the ITO layer remains at the bottom, the conductivity is largely retained, allowing repeated CV cycling. We consider operando ellipsometry a sensitive and nondestructive tool to monitor early stage material and property changes, either by tracing failure points, controlling intentional processes, or for sensing purposes, making it suitable for various research fields involving solid-liquid interfaces and electrochemical activity.

Degradation of 2,4-dinitrotoluene in aqueous solution by dielectric barrier discharge plasma combined with Fe–RGO–BiVO4 nanocomposite

2,4-Dinitrotoluene (2,4-DNT) as a priority and hazardous pollutant, is widely used in industrial and military activities. In this study the synergistic effect of Fe–RGO–BiVO4 nanocomposite in a non-thermal dielectric barrier discharge plasma reactor (NTP-DBD) for degrading 2,4-DNT was evaluated. Preparation of the Fe–RGO–BiVO4 nanocomposite was done by a stepwise chemical method depositing Fe and reduced graphene oxide (RGO) on BiVO4. Field emission scanning electron microscopy (FESEM), X-ray diffraction analysis (XRD), UV–vis diffuse reflectance spectra (DRS), and energy-dispersive X-ray spectroscopy mapping (EDS-mapping) validated the satisfactory synthesis of Fe–RGO–BiVO4. To find the optimal conditions and to determine the interaction of model parameters, a central composite design (RSM-CCD) had been employed. 2,4 DNT can be completely degraded at: initial 2,4-DNT concentration of 40 mg L−1, Fe–RGO–BiVO4 dosage of 0.75 g L−1, applied voltage of 21kV, reaction time of 30 min and pH equal to 7, while the single plasma process reached a degradation efficiency of 67%. The removal efficiency of chemical oxygen demand (COD) and total organic carbon (TOC) were 90.62% and 88.02% at 30 min contact time, respectively. Results also indicated that average oxidation state (AOS) and carbon oxidation state (COS) were enhanced in the catalytic NTP-DBD process, which demonstrate the effectiveness of proposed process for facilitating biodegradability of 2,4-DNT.

Laser powder bed fusion in situ alloying of AISI 316L-2.5%Cu alloy: microstructure and mechanical properties evolution

AbstractThis work investigates the effects of copper addition on the microstructure and mechanical properties of AISI 316L austenitic stainless steel fabricated by the laser powder bed fusion (L-PBF) method. The outcomes reveal that the copper atom dissolves into iron and forms a complete austenitic structure under the condition of the L-PBF process. Microstructural observations demonstrate that the microstructure of the new alloy is characterised by columnar grains consisting of finer cellular structures, as compared to the as-built AISI 316L. The appearance of such a finer sub-structure could be originated from the effect of copper on the cooling rate during the L-PBF process. The energy-dispersive X-ray spectroscopy maps indicate that the distribution of copper in the AISI 316L matrix is homogeneous, and no significant segregation of elements in the matrix is revealed. The results of the tensile tests show that the ultimate tensile strength of AISI 316L-Cu alloy is 558 MPa, whereas the yield strength value and the tensile elongation are 510 MPa and 30.4%, respectively. Two mechanisms of solid solution strengthening, and refinement of cell sizes improve the mechanical properties of AISI316L-Cu alloy compared with AISI 316L one. The microscale fractography of the fracture surface shows ductile fracture with massive dimple networks and brittle fracture with a quasi-cleavage plane, which may indicate the melt pool boundary. All these results confirm that the development of new alloys following the in situ alloying approach is economical and reliable.

The Source, Mobility and Fate of Bismuth (Bi) in Legacy Mine Waste, Yxsjöberg, Sweden

The usage of bismuth (Bi), a critical and strategic raw material, has increased in the last 10 years. At present, the knowledge of Bi geochemistry is too limited to develop accurate mine waste and water management strategies to prevent environmental impact. Therefore, its geochemistry was studied in historical tailings in Yxsjöberg, Sweden. Intact tailings cores and shore samples were geochemically and mineralogically analyzed. Groundwater was sampled between 2016 and 2021 and analyzed for 71 elements and (SO4, F, Cl). The results were correlated with metals and dissolved organic matter (DOC), which have been previously published. The total concentrations, sequential extraction and scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM–EDS) mapping indicated that Bi had been mobilized from the primary mineral bismuthinite (Bi2S3). In the oxidized tailings from both the cores and shore, Bi was hypothesized to have adsorbed to iron (Fe) (hydr)oxides, which prohibited high concentrations of Bi leaching into the groundwater and surface water. Dissolved Bi in groundwater was significantly correlated with DOC. In surface water, dissolved Bi was transported more than 5 km from the tailings. This study indicates that Bi can become mobile from legacy mine waste due to the oxidation of bismuthinite and either be scavenged by adsorption of Fe (hydr)oxides or kept mobile in groundwater and surface water due to complexation with DOC.

Enhanced photoelectrochemical performance of quantum dot-sensitized solar cell using Cu2+ co-doped CdS and CdSe nanoscrystals.

Today, nanoscrystals are researched and developed very quickly because of their advantages in many areas of life. One of the potential applications is quantum dot-sensitized solar cells. This is a green, clean, environmentally friendly cell, and has been studied by scientists since 2000. In this study, we fabricated photoanodes with Cu2+ ions co-doped into cadmium sulfide (CdS) and cadmium selenide (CdSe) nanoscrystals by successive ionic layer adsorption and reaction, and chemical bath deposition methods to improve absorption spectral intensity of films. The results showed that the absorption intensity increased by eight times compared with our previous results on Cu2+ ions doped with CdSe nanoscrystals. The CdS:Cu2+ film is optimized at 2% doping, the efficiency is 4.6819%, and the current density is 27.3501 mA.cm-2, which is higher when compared with the Cu2+ ion only doped into the CdSe quantum dot (19.915 mA.cm-2). In addition, the composition of the photoanode was determined by surface and cross-sectional field-emission scanning electron microscope images, and the structure of the film was determined by X-ray diffraction, energy-dispersive X-ray spectroscopy mapping and X-ray photoelectron spectroscopy. Finally, the film's optical properties were studied by ultraviolet-visible spectroscopy, photoluminescence spectroscopy and electrochemical properties by electrochemical impedance spectroscopy. The results obtained have been discussed and presented in great detail.

Process-structure-property studies on synergetic effect of contact and non-contact ultrasonication in AA5083-based bulk nanocomposite

High strength-to-weight ratio materials such as Al- and Mg-based nanocomposites have gained growing interest in engineering applications for aerospace, automotive, marine, energy, and military. This unabated demand can be met with the advent in materials science and processing technologies. The current study demonstrates a recently developed the technique that consists of the synergetic effect of contact and non-contact ultrasonication of liquid melt for dispersing nano-sized Al2O3 reinforcements in AA5083 alloy matrix. The work is primarily focused on the effects of two-step ultrasonication on wettability, dispersion of the nano-reinforcements in the AA5083 alloy matrix, and the resultant strengthening. The resultant is the AA5083–1 wt-% Al2O3 bulk nanocomposite, a high strength-to-weight ratio material. The extensive microstructure analysis comprising scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDS) mappings reveals the uniform dispersion of nano-particles in different phases of the matrix. The electron back scattered diffraction (EBSD) studies confirm the grain refinement while the X-ray diffraction (XRD) identifies the various phases formed are determined using XRD. The achieved uniform dispersion in the nanocomposite is explicated based on the enhanced wettability due to the presence of Mg in the alloy, preheating of nano-particles, and the synergetic effect of contact and non-contact ultrasonication that avoids the formation of zones of lower cooling rates resulting in powerful micro-convection. The resultant enhancement in the mechanical properties is explained based on available strengthening mechanisms. A comprehensive discussion on process-structure-property correlation has been presented.