Oxide Powders Research Articles

Carbon reduction of 3D-ink-extruded oxide powders for synthesis of equiatomic CoCuFeNi microlattices

Equiatomic CoCuFeNi high-entropy alloy microlattices are created by 3D-extrusion printing of an ink containing a blend of binary oxides (Co3O4+CuO+Fe2O3+NiO) and graphite (C) powders. After printing, the green parts are subjected to a series of heat treatments under Ar leading to (i) carbon reduction of the oxides to form metallic particles, (ii) interdiffusion of these metallic particles to create an alloy, and (iii) sintering to remove porosity. The phase evolution in individual extruded filaments (similar to struts in the microlattices) is observed by in-situ X-ray diffraction, showing that intermediate suboxide phases (Cu2O, CoO, Fe3O4, CuFeO2, and FeO) form as the original oxides are reduced by carbon, before the final metallic alloy is formed. At 830 °C, the extruded filaments comprise a face-centered cubic CoCuNi(+Fe) alloy with unreduced FeO inclusions. After reduction and sintering at 1100 °C, homogeneous, densified, equiatomic CoCuFeNi microlattices are achieved, containing small amounts of a Cu-rich phase. At room temperature, the compressive strength of these CoCuFeNi microlattices increases as the strut diameter decreases from ∼260 to ∼130 µm, as expected from an observed drop in strut porosity resulting from more complete sintering. This is consistent with the easier escape of CO+CO2 gas created during carbothermic oxide reduction from the thinner struts undergoing reduction and sintering.

Guided wave propagation in a high-speed rotating concrete shell reinforced by advanced nanocomposites

This paper investigates the propagation of guided waves in a high-speed rotating concrete shell reinforced with graphene oxide powders (GOP) using higher-order shear deformation theory (HSDT). The study addresses the complexities introduced by initial hoop tension and provides a comprehensive analytical solution procedure. Concrete shells are widely used in various engineering applications due to their robustness and durability; however, their mechanical performance can be significantly enhanced by the incorporation of GOP, which improves the material properties, such as tensile strength and modulus of elasticity. The analysis begins with the formulation of the governing equations based on HSDT, which accurately captures the effects of transverse shear deformation and rotary inertia, crucial for high-speed rotating structures. The presence of initial hoop tension, resulting from the centrifugal forces in the rotating shell, is integrated into the model to reflect real-world conditions. The modified equations are then solved analytically to obtain the dispersion relations for the guided wave modes. The results reveal that the inclusion of GOP significantly alters the wave propagation characteristics, enhancing the shell’s ability to transmit high-frequency waves with minimal attenuation. The initial hoop tension is found to shift the frequencies of the guided wave modes, indicating a coupling effect between the mechanical loading and wave propagation. This study provides valuable insights into the dynamic behavior of reinforced concrete shells in high-speed rotational environments, offering a potential pathway for the design of advanced structural components in aerospace, automotive, and civil engineering applications.

Cytotoxicity and antioxidant activity of iron oxide nanopowders synthesized by radiation-chemical method using different precursors

The study revealed a correlation between the cytotoxicity and antioxidant activity of iron oxide nanopowders produced by the radiation-chemical method and the choice of precursors (iron (III) nitrate or iron(II) sulfate), and the temperature of pre-annealing of the synthesized product, and also irradiation with accelerated electrons. Notably, high and lowabnormal cytotoxicity of aqueous suspensions of samples S300 and S400, respectively, annealed at temperatures of 300 and 400 °C, was observed for the first time at all concentrations (0.1–1.0 ml/mg). The likely cause of this abnormal cytotoxicity was identified as alterations in the textural and structural properties of NP after annealing.Furthermore, a significant impact of electron beam irradiation on the antibacterial and antioxidant properties of both unannealed and annealed iron oxide NP was discovered with irradiated samples exhibited lower cytotoxicity compared to non-irradiated ones. Additionally, the deposition of nanosilver on the surface of iron oxide powders was found to significantly influence their biological properties, with the survival of Vero cell cultures being dependent on the composite concentration in the aqueous suspension.A study of the oxidative stress of composites based on iron oxides coated with silver showed that they significantly increased cell viability, and at a concentration of 1 mg/ml provided complete mitigation of oxidative stress in cells.

Pressed Solid Target Production of 89Zr and its Application for Antibody Labelling.

Zirconium-89 ( 89Zr, t1/2=3.27d) is an important + emitting radionuclide used in Positron Emission Tomography (PET) immuno studies due to its unique characteristics and increased demand due to simple and cost-effective production capacity. Production of 89Zr is achieved primarily through solid natural yttrium targets via different target preparation methodologies, such as electrodeposition, pressed foils, and spark plasma sintering. In this study, we have investigated the pressed solid target methodology. The Yttrium Oxide (Y2O3) powder was pressed to pellet form and stacked over a different back support plate, such as platinum (Pt), niobium (Nb), and tantalum (Ta). The target was irradiated with approximately 12 MeV proton beam for 10-60 minutes at 20µA current. The irradiated target was purified through a solid phase extraction method via hydroxamate-based resin by manual or automatic approach. The purified 89Zr was analyzed using gamma scintigraphy, and specific activity was calculated through Deferoxamine (DFO) chelation. 89Zr radionuclide via pressed target was effectively produced with a production yield of 20-30 MBq/µA.h, and the purification was achieved in 35 minutes with (87.46)% average recovery and >98% purity while using automated purification, but manual purification took 2 hours with (91 ± 2)% recovery and >98% purity. The production yield was comparable to the reported pressed target approach. Deferoxamine (DFO) chelation with 89Zr-oxalate was performed with purity >98% and specific activity of 25-30 µCi/mmol. In this study, we explored the production of 89Zr by pressed targets and purification via manual or automated methods with good radionuclide purity. The chelation with DFO or its analog was performed with good labeling efficiency and stability</p>.

Single iron particle combustion - A morphology study of partially oxidized iron particles

In recent years, metal fuels were discussed as a contribution to meeting the challenges of the energy transition to a climate-friendly, sustainable energy economy. One material system with high potential to store and release a large amount of energy is iron powder and its reducible solid product iron oxide powder. In this study, the evolution of the particle morphology during single particle combustion in a laminar flow reactor is analyzed. Partially oxidized iron particles are sampled at different heights above the burner and their internal morphological structure is revealed qualitatively and quantitatively by tomography and microscopy methods (μCT, SEM, EDX, EBSD). The findings show that interfacial phenomena might play a major role when describing single particle combustion as the existence of two liquid phases with emulsification phenomena can be detected. Based on the results, a morphological description of the oxidation progress is proposed within the frame of this work.

Surface-Activated Graphite Oxide Nanosheets with Promoted U(VI) Adsorption Performance

Adsorption is widely regarded as the most promising method for uranium extraction. Among the various materials that have been studied, graphene oxide (GO) has attracted intensive interest because of its large specific surface area and abundant oxygen-containing functional groups. However, the layers tend to aggregate owing to pronounced Van der Waals forces, which reduce the surface area and diminish the likelihood of contact between uranyl ions and adsorption sites. Graphite oxide is an intermediate product of GO, with a simple preparation process and low cost. In this study, graphite oxide nanosheets (GONs) were synthesized using graphite oxide powder as the raw material and the NaOH activation method. GONs possessed a larger specific surface area and more carboxyl groups, which resulted in an excellent uranium adsorption capacity. The maximum adsorption capacity was found to be 578.0 mg·g−1, and the adsorption rate was 90.8% within 30 min. The adsorption process closely resembled the pseudo-second-order model and the Langmuir model. The mechanism of uranium adsorption by GONs was the synergistic coordination of -COOH and -OH with U(VI). This research suggests that the novel uranium adsorbent GONs can be applied to efficiently capture U(VI) from radioactive wastewater.

Nonlinear resonant analyses of graphene oxide powder reinforced hyperelastic cylindrical shells containing flowing-fluid

The resonant responses are investigated for the graphene oxide powder reinforced hyperelastic cylindrical (GOPRHC) shells containing flowing-fluid, and the shells are subjected to the radial harmonic excitations. Employing the improved Donnell's nonlinear shell theory, Halpin-Tsai model, hyperelastic constitution relation, velocity potential theory and Lagrange equation, the governing equation of motions are obtained for the GOPRHC shells containing flowing fluid. The amplitude frequency and force amplitude curves are presented by using the harmonic balance method and the pseudo-arc length continuation method. The effects of three distributions of the GOP, weight fraction of the GOP and fluid velocity on the natural frequency for the GOPRHC shells are discussed. The influences of different parameters on the dynamical responses for the GOPRHC shells containing flowing-fluid are conducted, including the external excitation, weight fraction of the GOP, fluid velocity and structural parameters. The results show that the GOPRHC shells with Hypere-X distribution containing flowing-fluid have the largest frequency. The super-harmonic resonance responses appear and present the synchronization effects with the primary resonant responses in the GOPRHC shells containing flowing-fluid. The increases of external excitations, fluid velocity, weight fraction of the GOP and structural parameters enrich the resonant responses for the GOPRHC shells. Compared to the fluid-filled hyperelastic cylindrical shells, the existence of the flowing-fluid makes the GOPRHC shells more prone to the chaotic vibrations. The hysteresis phenomena of chaotic vibrations occur in the GOPRHC shells containing flowing-fluid.

Synthesis of Copper–Nickel and Iron–Nickel Alloys by Hydrogen Reduction of Mixtures of Metal Oxide Powders

The vast majority of metals production is based on the use of carbon as a reductant and/or a heating fuel. This results in a large amount of carbon dioxide emissions and should be minimized to limit global warming. In this study, powders of copper–nickel alloy and iron–nickel of varying compositions were produced in a single step by reduction of mixtures of Cu2O-NiO and Fe2O3-NiO powders, respectively, using hydrogen as a reductant. Reduction was performed in a horizontal tube furnace at 700 °C for 45 min. All processing was in the solid state and alloys were produced directly from elemental metal oxides. Exhaust gases were analyzed using a gas analyzer to measure the water content to track the progress of the reduction. Reduction was declared complete when the water content in exhaust gases matched the level before hydrogen was introduced. Both copper–nickel and iron–nickel alloys were produced successfully. X-ray diffractometry confirmed the absence of oxides in the product and the presence of solid phases in agreement with the relevant binary phase diagram. Energy-dispersive X-ray spectroscopy in a scanning electron microscope showed macroscopic homogeneity at the expected composition for each powder mixture directly after reduction, with microscopic fluctuations of the order of several mass percent, within the limits of fluctuations observed following typical casting processes. These promising results warrant further investigation to apply this concept to more chemistries and to scale up the process to a pilot scale.Graphical

Enhancing the stability and efficiency of the advanced concrete structures surrounded by an auxetic foundation

This study delves into the vibrational characteristics of concrete annular plates reinforced with graphene oxide powders (GOP), underpinned by an innovative auxetic-elastic foundation. By applying Hamilton’s principle, the governing dynamic equations are meticulously derived, incorporating the effects of internal forces and GOP geometrical properties. The Differential Quadrature Method (DQM) is utilized to solve these equations, providing a robust and efficient numerical approach for analyzing the system’s complex dynamic behavior. GOP reinforcement significantly enhances the mechanical properties of the concrete plates, yielding improved stiffness and superior damping capabilities. The auxetic-elastic foundation, known for its unique property of becoming thicker perpendicular to the applied force, plays a pivotal role in altering the vibrational response of the system. The study meticulously examines the influence of this foundation on the system’s vibrational behavior, highlighting its potential to enhance performance under varying operational conditions. A comprehensive analysis is conducted to understand the effects of different boundary conditions on the vibrational characteristics of the reinforced concrete annular plates. The results underscore the importance of integrating advanced materials like GOP and innovative foundation designs in optimizing structural components. This study provides valuable insights into the design and application of reinforced concrete structures, emphasizing the effectiveness of GOP reinforcement and auxetic-elastic foundations in enhancing vibrational performance. These findings offer a significant contribution to the field of structural engineering, paving the way for future innovations in the design of resilient and efficient structural systems.

Improving oxidative stability of cream powder using pomegranate concentrate and peel extract.

In this study, the influence of pomegranate peel extract (PPE) and pomegranate concentrate (PC) on improving the oxidative stability of cream powder in comparison with synthetic antioxidant (Butylated hydroxytoluene (BHT)) during the storage period at 20°C (8 weeks) and 45°C (4 weeks) was evaluated. The finding exhibited that peroxide, p-anisidine, and total oxidation (TOTOX) values increased during the storage period. Samples containing PPE and PC showed suitable performance in controlling the cream powder oxidation. Also, PPE showed the highest antioxidant activity and can be proposed as a suitable replacement for a synthetic antioxidant (BHT). L* and b* values increased, while a* value decreased during the storage period. Also, the pH of the powders decreased significantly throughout the storage (reached nearly 6). Microbial counts of cream powders did not change during the storage period. The control sample showed the highest overall acceptability. Antioxidants of pomegranate can be proposed to control the oxidative stability of fat-rich food products.

The effect of particles size of Gd2O3 on the radiation protection mechanisms of ZnO

There are two mechanisms established for increasing the radiation resistance of optical properties of micron-sized zinc oxide (mZnO) powder modified by gadolinium oxide (nGd2O3) nanoparticles by means of relaxation of the primary radiation defects (electrons and holes): — in atoms of rare-earth element gadolinium; — on Gd2O3 nanoparticles. During modification with gadolinium oxide micron-sized particles, only one (first) mechanism for radiation resistance increasing is enabled. These results are obtained by recording diffuse reflectance spectra in high vacuum in the range of 0.2–2.5 μm under radiation exposure by accelerated electrons (in situ). The established mechanisms for increasing radiation resistance refer not only to the types of powders under the study, but also to other types of oxide semiconductor powders and rare-earth elements. These mechanisms can also be extended to the photo résistance of oxide powders modified by nanoparticles and solid solutions based on them.

Application of innovative SVM-PSO-GA algorithm to study vibrations of improved perovskite solar cells

This study investigates the vibrations of graphene oxide powders (GOPs) reinforced perovskite solar cells surrounded by an elastic foundation using both mathematical modeling and innovative machine learning algorithms. The incorporation of GOPs into the perovskite matrix enhances the mechanical properties and stability of the solar cells, which are crucial for their durability and efficiency. The analysis is conducted through the application of Hamilton’s principle, providing a robust theoretical framework for deriving the governing equations of motion. An analytical method is employed to solve these equations, allowing for the accurate prediction of the vibrational behavior of the reinforced solar cells. The effects of various parameters, including the stiffness of the elastic foundation and the concentration of GOPs, are systematically examined. This study presents the application of an innovative Support Vector Machine (SVM)-Particle Swarm Optimization (PSO)-Genetic Algorithm (GA) to analyze the vibrations of GOPs reinforced perovskite solar cells surrounded by an elastic foundation using mathematical modeling datasets. The SVM-PSO-GA algorithm to enhance predictive accuracy. The integrated approach leverages the strengths of each method to model and predict the vibrational behavior of the reinforced solar cells. The results highlight the algorithm’s effectiveness in capturing complex interactions and optimizing design parameters, providing valuable insights for improving the stability and performance of perovskite solar cells in practical applications.

Spark plasma sintering of boron carbide (B4C): From characterisation to finite element modeling of sintering

Boron carbide (B4C), known for its unique properties, presents challenges in reaching its full density with sintering process due to low diffusion coefficients. This study explores the application of Spark Plasma Sintering (SPS) to overcome these challenges and enhance the understanding of its impact on pure B4C ceramics. The study outlines a comprehensive methodology for developing an SPS sintering model. Starting with a summary of conducted studies, powder oxidation analysis, characterization methods, and dilatometry curves processing, the article details the derivation of constitutive parameters based on the Skorohod-Olevsky theory. Isothermal profiles at different temperatures, variation in heating regimes, and a stepwise approach for SPS pressure application form the basis of the derivation methods. A grain growth model is developed for a comprehensive simulation of sintering, incorporating microstructural analysis and parameter derivation. Finally, the article addresses the integration of this mechanical sintering model with thermal and electrical considerations into a finite element method (FEM) software for a holistic SPS modeling. Thermo-electrical considerations, including the Peltier effect, are also computed, providing a well-rounded understanding of the SPS process for B4C ceramics. This study contributes valuable insights to optimizing the SPS parameters to achieve enhanced densification and microstructure control in B4C ceramics.

Graphene-based aerogel for efficient oil sorption and water pollution remediation

In the past few years, there has been a notable rise in the release of industrial waste oil, frequent oil spills at sea, and a significant escalation in the severity of water pollution. This issue has garnered global attention and is now recognised as a widespread concern. Hence, there is a pressing demand for an oil-absorbing material exhibiting high oil-absorption capabilities and robust mechanical properties. This study introduces a new aerogel characterised by a three-dimensional hierarchical pore size structure derived from natural corn stalk powder and graphene oxide (GO). The developed aerogel demonstrated notable sorption capacity ranging from 70.6 to 131.0 g/g, along with excellent compressibility and high elasticity. These properties enable effective oil-water separation and selective sorption. This study introduces a novel approach to treating agricultural waste and presents a straightforward, environmentally friendly, cost-effective method for synthesising high-performance graphene-based oil-absorbing agents.

Mechanical Properties of Adjacent Pile Bases in Collapsible Loess under Metro Depot

Metro transit construction has begun to develop rapidly in northwest China because of the acceleration of urbanization. Accordingly, metro depots are also regarded as an essential auxiliary facility for stopping, operation, and maintenance of trains. Meanwhile, many commercial buildings are constructed over metro depots to improve the utilization rate of land due to the increasingly scarce urban land resources, known as transit-oriented development (TOD). These buildings have a large covered area and transfer concentrated loads to the bases. Therefore, pile bases under metro depots have the bearing characteristics of undertaking large concentrated loads, while lesser loads are placed on the soil between the adjacent pile bases. Additionally, the main ground in northwest China is collapsible loess, so the collapsibility should also be considered. Based on the above background, this research performed static loading tests with and without immersion in a reduced scale of adjacent pile bases under a metro depot in Xi’an. The remolding process of natural loess could destroy its structure and the anisotropy of natural loess could also affect the test results. Therefore, four kinds of artificial collapsible loess with different mass ratios of barite powder, kaolin, river sand, cement, industrial salt, and calcium oxide were made by the free-drop method. This method could make the artificial loess simulate the structure of natural loess reasonably. Then, the artificial loess with the most similar properties to intact loess was selected by comparison. Finally, static loading tests with this artificial loess were implemented. The results showed that the ultimate bearing capacity was 4.5 kN. At the same time, the axial force decreased along depth, since the pile shaft friction was positive, and the load sharing ratio of pile tip force increased to 0.58 when the load exceeded 4.5 kN in the situation without immersion; the settlement of pile bases increased significantly after immersion, while the negative shaft friction occurred at the depth of −8 cm~−35 cm, and the load sharing ratio of pile tip force reached 0.92.

On-demand engineered double-network gelatin/silicate composited hydrogels with enhanced wet adhesion and stable release of bioactive ion for promoting wound healing

Silicate bioceramics have demonstrated great potential in hydrogel dressings for wound healing due to their special origins of promoting endothelial cell angiogenesis and inhibiting apoptosis of cardiomyocyte. However, there are still some deficiencies, such as insufficient biological activity, instability of silicate ion release, and lower wet adhesion on wounds with tissue exudate, limiting their further clinical applications. Herein, inspired by mussels, a multifunctional double-network hydrogel (FS/PAM-Gel-PDA) wound dressing composited gelatin with silicate ceramic powder with satisfactory wet adhesion, stable release of bioactive ions, hemostasis, and the ability of promoting vascular regeneration was engineered through specifically grafting dopamine to gelatin and introducing ferrous silicate ceramic powder into the hydrogel. The comprehensive experimental results substantiate that the FS/PAM-Gel-PDA has wet-adhesion strength of up to 21.78 kPa, and remains stably adherent to porcine myocardial tissues intuitively after bending, twisting, soaking in water, and stretching. The test results of ion release behavior in vitro show that the oxidation and agglomeration of ferrous silicate ceramic powder can be effectively inhibited by using dopamine to form an antioxidant layer on the surface of ceramic powder, and thus, the stable release of Fe2+ and SiO44− effective ions can be realized. The animal experiment exhibits that FS/PAM-Gel-PDA can achieve rapid hemostasis in the lethal liver defect model. Meanwhile, the FS/PAM-Gel-PDA reveals the remarkable ability to promote wound healing in a full-thickness skin injury model, which can obviously accelerate skin re-epithelialization. To sum up, the FS/PAM-Gel-PDA has excellent wet adhesion and stable release of active ions to accelerate angiogenesis, which shows great potential in promoting wound healing.Graphical

Ni-based ODS alloy prepared by direct energy deposition process: powder fabrication, microstructure, mechanical property, and oxidation resistance

Ni-based ODS alloy prepared by direct energy deposition process: powder fabrication, microstructure, mechanical property, and oxidation resistance

Frequency Responses of a Graphene Oxide Reinforced Concrete Structure

This paper presents a comprehensive investigation on the vibrations of reinforced concrete structure by graphene oxide powders (GOPs) using a polynomial displacement field and the Generalized Differential Quadrature Method (GDQM). The study focuses on analyzing the dynamic behavior of the structure and assessing the effects of three different distribution patterns of GOPs on its vibrations. To accurately model the deformation of the pressure vessel, a polynomial displacement field is employed, taking into account the complex geometrical and material properties of the structure. The results highlight the significant influence of the distribution pattern of GOPs on the natural frequencies of the spherical concrete pressure vessel. The analysis reveals that variations in the weight fraction and arrangement of GOPs have a direct impact on the stiffness and dynamic characteristics of the structure. Specifically, increasing the weight fraction of GOPs generally leads to higher natural frequencies, indicating enhanced structural rigidity. Moreover, the polynomial displacement field and GDQM demonstrate their effectiveness in accurately predicting the vibrations of the reinforced pressure vessel. The combination of these numerical techniques enables efficient and reliable analysis of the dynamic response, allowing for optimization of the design and performance of spherical concrete pressure vessels.

Electrochemical Preparation of Ti2CrV Alloy in CaCl2 Melt

Ti2CrV alloy shows good hydrogen storage characteristics at room temperature and ambient pressure. The present study investigated the feasibility of direct electrochemical reduction of TiO2-Cr2O3-V3O5 to Ti2CrV in CaCl2 melt at 900 °C by the FFC Cambridge process. The electrolysis was conducted in a two-electrode assembly with the sintered mixed oxide cathode and HD graphite anode at a constant cell voltage of 3.1 V for different time intervals to elucidate the reduction mechanism of the metal oxide mixture. The obtained products were characterized by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy techniques. Cyclic voltammetry studies using metallic cavity electrode containing mixed metal oxide powder were also carried out to determine the electrochemical reduction behavior in CaCl2 melt at 900 °C. It was observed that the presence of pre-formed Cr and V metal in the vicinity of titanium oxide helped in its faster reduction. The complete metallization of the sintered mixed oxide pellet occurred after 15 h of electrolysis. The electrochemical reduction mechanism was observed to proceed through various intermediates such as chromium-rich Cr-V, vanadium-rich V-Cr, CaTiO3, TiO, Ti6O, Ti-V, and C15-TiCr2.

Highly efficient sunlight‐driven photodegradation of industrial dyes by Ni‐, Cu‐, and Zn‐doped MgO nanopowders

AbstractThis study provides the first ever investigation of the influence of nickel, copper, and zinc additives upon magnesium oxide powders when synthesized via sol–gel autocombustion. In order to assess the resulting properties of the samples affected by the addition of Ni, Cu, and Zn ions, a number of investigative techniques were employed, among which were X‐ray diffraction (XRD), Fourier transform infrared (FT‐IR) spectroscopy, scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X‐ray photoelectron spectroscopy (XPS), ultraviolet (UV)–visible diffuse reflectance spectroscopy (UV‐DRS), photoluminescence (PL) spectroscopy, and vibrating sample magnetometry (VSM). From XRD results, it was apparent that when Ni, Cu, and Zn ions are added to MgO, cubic solid solutions of NiMgO, CuMgO, and ZnMgO are created. UV‐DRS analysis showed significantly improved absorption levels in the samples that were optimally modified compared to the pure sample across UV, visible, and infrared spectral observations. Analysis of the photocatalytic activity exhibited by the synthesized samples was performed by considering the decomposition under sunlight of rhodamine B, methylene blue, methyl orange, and methyl red. The degradation under sunlight for these organic dyes was shown to be superior to that of pure MgO, achieving a range of 91%–95% in just 150 min.