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Almost all antimicrobial nanoparticles are commercially available as fine powders and are used in powdered form during the production of antimicrobial products. However, standard antimicrobial procedures are conducted on solutions or stable colloids. This means that nanoparticles are tested in a colloidal mono-disperse form, while in the production process, they are utilized as powders that contain aggregated structures. Consequently, existing standard procedures do not accurately reflect the true antimicrobial potency of nanopowders in antimicrobial products. Therefore, there is a need to modify the standard tests to enable antimicrobial testing on nanopowders, incorporating any dispersion or colloidization process. In the current study, the agar cell diffusion method was introduced as a novel approach to address this need. In this method, a well was created on a Muller-Hinton agar plate inoculated with bacteria. Antimicrobial nanopowders were mixed with molten agar and used to fill the well. An agar cell was formed, and after 18 h of incubation, the inhibition zone was measured. Using this method, the antimicrobial potency of Cu(OH)2 and ZnO nanopowders was evaluated. Cu(OH)2 nanopowder was synthesized through a plant-mediated precipitation reaction using Nigella sativa seed extract, while ZnO nanopowder was purchased commercially. It was found that the examined strain of Pseudomonas aeruginosa was resistant to both nanopowders. Cu(OH)2 nanopowder was more effective against Escherichia coli, with a growth inhibition zone of 15 ± 0 mm. Meanwhile, ZnO nanopowder was most effective against Staphylococcus aureus, showing a growth inhibition zone of 12.3 ± 0.58 mm. [ABSTRACT FROM AUTHOR]

In this research, CdWO4 (CWO) and Ag-doped CWO (Ag: CWO) nanopowders were synthesized using the easy, quick, and cost-effective co-precipitation method, considering the wide application of tungstate compounds in optoelectronics, the optical capabilities of noble metal nanoparticles (NPs), and the problems of the crystal growth process. The structural and optical properties of the prepared nanopowders were thoroughly investigated. XRD results verified the production of both nanopowders with monoclinic (wolframite) crystal structures. The lattice parameters, crystallite size, and lattice strain of both CWO and CWO: Ag nanopowders were compared using Rietveld refinement and Williamson-Hall (W-H) analysis. The presence of Ag dopant was confirmed by the observed decrease in the intensity of the vibrational mode of ν1 (Ag) at 896 cm-1 in the CWO: Ag Raman spectrum. FE-SEM and TEM images showed that Ag ions increased the size of CWO NPs and introduced some nanorods with a diameter of approximately 29 nm. Photoluminescence (PL) measurements at 2 excitation wavelengths and Ion Beam-Induced Luminescence (IBIL) results revealed that the shallow level of Ag+ dopant near the conduction band of WO66- enhanced its luminescence properties under UV (λ exc=280nm) and ion beam (E=2.2 MeV) excitations. Antibacterial analyses revealed that CWO: Ag nanopowders eliminated over 99.9% of Gram-negative bacteria Escherichia coli (E. coli) in 6 hours. Based on the results, CWO: Ag nanopowder has great potential in laser technologies, spectroscopy, medicine, and E. coli sensors.

The primary objective of materials science is the study of the properties of the existing materials and the development of new ones. In the present day, the use of solid-state lasers abroad has prompted material scientists globally to develop novel or enhance the properties of the existing active gain media. Materials comprising rare earth elements have historically proven effective in scintillation applications. The synthesis of LaLu 1-x Yb x O 3 monodisperse nanopowders with a particle size of 50–62 nm via the Pechini complexing citrate method has been the subject of investigation using electron paramagnetic resonance (EPR) spectroscopy and photoluminescence (PL) measurements. The EPR data indicate that the Yb³⁺ ions predominantly create a single type of center, whereby the Yb³⁺ ion substitutes for the Lu³⁺ ion. The calculated EPR g-factors are estimated to be g 1 = 3.85, g 2 = 2.15, g 3 = 1.55 and the 171Yb isotope hyperfine interaction constants are A 1 = 600 × 10−4 cm−1, A 2 = 700 × 10−4 cm−1, A 3 ≈ 1800 × 10−4 cm−1. The principal values of the g factors and the hyperfine tensors indicate that the Yb site in LaLu 1-x Yb x O 3 nanopowders exhibits orthorhombic symmetry. The PL measurements in the wavelength range of 350–1800 nm, with excitation provided by either a xenon lamp or a diode laser, indicate the presence of a broad emission band, centered at 404 nm, in addition to the well-known emission spectrum in the IR region (920–1100 nm) arising from Yb3+ ions. [ABSTRACT FROM AUTHOR]

Using citric acid, ethylene glycol, ZrOCl 2 ·8H 2 O, HfOCl 2 ·8H 2 O, NbCl 5 , and TaCl 5 as raw materials, based on the principle of Pechini coordination polymerization, the (Zr 0.25 Hf 0.25 Ta 0.25 Nb 0.25)C high-entropy ceramic precursor solution was successfully prepared, and the corresponding high-entropy ceramic powder was formed by pyrolysis at a low temperature of 1500 °C. The molecular structure of the precursor and its pyrolysis products were analyzed and characterized by different analytical and testing methods. The results show that in the precursor solution, the organic compound and the metal ions form a stable three-dimensional macromolecular structure, so that the metal ions show a uniform distribution at the molecular level, shortening the diffusion path during the carbothermal reduction reaction, thereby enabling the formation of the single-phase high-entropy carbide ceramic powders at a relatively low temperature. The obtained ceramic powders have high purity, uniform element distribution, with an average particle diameter of approximately 42 nm and an oxygen content of about 1.61 wt%. The precursor solution prepared in this study has a moderate viscosity of 20–50 mPa s and a high ceramic yield of 45 %, which is ideal for the preparation of high-entropy ceramic matrix composites. [ABSTRACT FROM AUTHOR]

The main directions and fields of the application of metal nanopowders in joining technologies are considered. Based on this analysis, the purpose of this research was to determine the effect of tungsten nanopowder on the structure and properties of the deposited metal. In order to increase the efficiency of using tungsten nanopowder for modification, it is necessary to ensure the introduction of nanopowder into the low-temperature zone of the molten metal during surfacing. To study the metal, microstructural analysis was performed, and the microhardness of the deposited joint was determined. On the basis of the conducted studies, a change in the structure of the deposited metal and an increase in mechanical properties were revealed. A conclusion is made about the effect of tungsten nanopowder on the metal modification process during manual metal arc, metal inert gas, and flux-cored arc welding. Based on the conducted studies, it was found that the introduction of tungsten nanopowder into the low-temperature zone of the molten metal ensures the modification of the surfacing and induces an increase in the microhardness of the deposited metal. At the same time, grains of polyhedral morphology are formed at the surface, and the structure of oriented dendrites at the boundary of fusion with the base metal is also revealed, showing the peculiarities of the distribution of microhardness in various surfacing methods. The minimum and maximum values of microhardness depend not only on the nanopowder but also on the method of its introduction into the molten metal. [ABSTRACT FROM AUTHOR]

The synthesis of barium hexahydroxostannate BaSn(OH)6 and its thermal destruction leading to the barium stannate BaSnO3 have been studied. It is shown that the most intensive decomposition of BaSn(OH)6 occurs in the temperature range of 200–650°C. Crystallization of BaSnO3 proceeds in a narrow temperature range (650–675°C), and the maximum of the corresponding exo-effect is located at 667°C. It was found that at 500°C (within 60 min) BaSn(OH)6 completely decomposes with the formation of X-ray amorphous powder. When the material is kept at 600°C (60 min), crystallization of barium stannate BaSnO3 with perovskite structure takes place. The crystalline impurity of barium carbonate contained in the semiproduct is preserved up to 600°C, and at temperatures from 700°C the single-phase BaSnO3 is formed. The crystallization temperature of barium stannate can be reduced by 50–75°C due to thermal exposure of the powder for 40–60 min. Holding the semiproduct at 600°C for 60 min forms barium stannate with an average crystallite size of 21 ± 2 nm, and at 700°C there is a slight increase in this parameter (up to 22 ± 2 nm). With increasing temperature up to 1000°C there is intensification of crystallite enlargement process (up to 34 ± 3 nm). The obtained BaSnO3 powder, according to scanning electron microscopy data, consists of microrods (average length is about 85 μm; average diameter is about 10 μm). The surface of the rods is partially covered with spherical particles formed from smaller primary particles of about 30 nm in size. [ABSTRACT FROM AUTHOR]

In this work, we present the electrochemical synthesis of zinc oxide in the presence of surfactant TERGITOL 15-S-5. A sodium chloride solution was used as the electrolyte; a zinc block as the anode, and a steel plate as the cathode; TERGITOL 15-S-5 as the surfactant. The electrolyzer consists of a power supply B5-46, which ensures constant current during electrolysis; a voltmeter and ammeter to monitor the current strength and voltage; electrodes connected to the power supply and immersed in a 1 M sodium chloride solution (58.45 g/L) or a solution with the same concentration of sodium chloride and dissolved surfactant – TERGITOL 15-S-5 (from 1 to 4 g/L). The beaker containing the electrolyte solution was stirred with a magnetic stirrer and thermostated. In the electrochemical method, the surfactant content was varied (from 1 to 4 g/L). A total of 6 experiments were conducted. Six deposits were isolated and studied. Using the X-ray phase analysis, we established that the deposits are pure zinc oxide in the wurtzite modification (space group P63mc) and additional phases are not observed. SEM analysis also confirmed that the material contains only nanoparticles of zinc oxide. The crystalline structure of the obtained zinc oxide indicates that it can be modified by adding atoms with a smaller atomic radius compared to zinc atoms, as all octahedral voids are free, while only 2 out of 8 tetrahedral voids are filled with zinc atoms. The structure is non-centrosymmetric, suggesting that such materials may possess nonlinear optical properties. The zinc oxide particles have a plate-like shape with a width of 30-600 nm and a length of 50-2500 nm. All obtained deposits consist of nanosized particles with a thickness in the range of 20-40 nm. The addition of the surfactant TERGITOL 15-S-5 contributes to a slight increase in particle sizes. [ABSTRACT FROM AUTHOR]

The present study proposes machining Ti-6Al-4V with graphite nanopowder mixed electric discharge machining (NPMEDM) process using deionized water (6 gm/L) as the dielectric. A comparative analysis is performed with conventional electric discharge machining (EDM) and NPMEDM processes with peak current (IP), pulse on time (TON), and gap voltage (GV) as input parameters. Surface integrity, recast layer thickness (RLT), material removal rate (MRR), chemical analysis, and residual stress are investigated by different characterization techniques such as field emission scanning electron microscopy (FESEM) and x-ray diffraction (XRD). FESEM study reveals that the addition of nano graphite powder leads to a glossy surface finish, lesser micro-cracks, and micro-holes. Recast layer thickness (RLT) improved drastically by 69% with the addition of graphite powder. The investigation also revealed an improvement in surface roughness by 74.75% in NPMEDM compared to conventional EDM. Further, the induced residual stress is investigated by XRD analysis. Obtained results reveal substantial improvement in residual stress from (340.5 ± 12.6) to (239.9 ± 62) MPa, which diminishes the chance of failure of the component. [ABSTRACT FROM AUTHOR]

Some physical and technological features of the electroconsolidation process were considered to determine its place among numerous electrodischarge sintering methods. Principal advantages over the other nanopowder compaction methods were noted. The effect of sintering regimes on the formation of a microstructure, the specific features of inhibition under heating in the growth of grains, and the temperature of the graphite press mold and the rate of its heating on the physicomechanical properties of ceramic composites was studied. Some original data on the electroconsolidation process were reposted alongside with the physicochemical properties of nanocomposites synthesized by this method. The probable scheme of electrodischarge processes under high-ampere currents through the graphite press mold is presented. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Metallurgical Quarterly is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Using powder metallurgy methods by sintering in vacuum at temperatures from 1300 to 1500°C, materials with porosity from 67.5 to 82.5% are obtained from mixtures of titanium carbide powders and ammonium bicarbonate as a pore-forming agent. Using X-ray phase analysis, it is established that the crystal lattice parameter of the resulting porous materials decreases with increasing sintering temperature. This indicates a decrease in the content of bound carbon C/Ti in titanium carbide. As a result of a comparative study of the strength characteristics of materials synthesized from nano- and submicron titanium carbide powders obtained from bending tests, it is found that they have similar values. Ultimate bending strength is in the range from 2.6 to 18.1 MPa. As the porosity of the material increases, the tensile strength decreases. The destruction is fragile. In the fracture of materials obtained from titanium carbide nanopowder, destruction is observed both along the body and along the grain boundaries regardless of the sintering temperature. In materials obtained by sintering submicron titanium carbide powder at 1500°C, destruction occurs predominantly along the body of the grains. It is revealed that, under the same sintering conditions, the density of porous material obtained from titanium carbide nanopowder is higher than that of the material obtained from submicron powder. [ABSTRACT FROM AUTHOR]

The work is devoted to a technique for measuring the speed of sound when passing through a thick layer of "poured" nanopowder in an immersed state. A simple experimental setup is proposed consisting of two speakers and one microphone immersed in a container with a nanosized powder. The setup does not require calibration. Two indirect methods for determining speed in the nanopowder using two speakers and a microphone located at different distances from the speakers are shown. Experimental measurements are carried out in a silicon dioxide nanopowder with an average particle size of about 50 nm. It has been established that the speed of sound in this medium is less than that in gas and solid matter and is equal to 35 m/s. It has been shown that the speed of sound does not depend on the frequency of sound for frequencies up to 1600 Hz. A new hypothesis has been proposed that the nanopowder behaves like a new type of continuous medium, "heavy gas," when a sound wave passes through it. The hypothesis allows one to apply formulas for determining the speed of sound in gas for this case. Based on experimental data, the adiabatic constant for the "heavy gas" is estimated. The proposed application of the effective medium approximation, such as the Hertz–Mindlin contact theory, to estimate the speed of sound in nanopowder shows that the nanoparticles are not in close contact with each other. This can be explained by the inapplicability of this theory to the case of "poured" nanopowder due to the packing of nanoparticles that differs from the theory. [ABSTRACT FROM AUTHOR]

Polymeric sheets of poly(methyl methacrylate) loaded with organic dye with various amounts of metal oxide nanopowder are promising alternatives to traditional inorganic materials, as they have similar mechanical properties to flexible substrates with relatively high refractive index that can be used in flexible optical/optoelectronic devices. Polymeric sheets of poly(methyl methacrylate) loaded with boron subphthalocyanine chloride with various amounts of cerium(IV)-zirconium(IV) oxide nanopowder were fabricated. Fourier transform infrared spectroscopy and X-ray diffraction techniques were used to examine and analyse the structure of the fabricated polymer sheets. Introducing organic dye and nanofiller in the polymer molecular chains matrix does not change the infrared characteristic transmission peaks. The X-ray diffraction spectra of the polymeric sheets have an amorphous nature. Characterized by spectroscopic measurements (fluorescence, transmittance, and reflectance), the optical properties such as the optical energy gap, emission bands, and refractive index of the fabricated polymer sheets were explored. By controlling the concentration of boron subphthalocyanine chloride and cerium(IV)-zirconium(IV) oxide nanopowder, energy gaps and the refractive indexes of the fabricated polymer sheets can be controlled. The poly(methyl methacrylate) loaded with boron subphthalocyanine chloride with 20 mg cerium(IV)-zirconium(IV) oxide nanopowder showed optical energy gap transitions at 4.79, 2.66 eV, and 2.08 eV, it has the highest PL intensity with a strong emission band at 413 nm, and also it has the highest refractive index. Finally, the obtained experimental results showed that the prepared polymer systems can be considered promising flexible polymer sheets for optics, and photonics devices. [ABSTRACT FROM AUTHOR]

The process of obtaining powders from the 5–50 μm fraction of a W-Ni-Fe system consisting of particles with predominantly spherical shapes was investigated. Experimental studies on the plasma–chemical synthesis of a nanopowder composed of WNiFe-90 were carried out in a plasma reactor with a confined jet flow. A mixture of tungsten trioxide, nickel oxide, and iron oxide powders interacted with a flow of hydrogen-containing plasma generated in an electric-arc plasma torch. The parameters of the spray-drying process and the composition of a suspension consisting of WNiFe-90 nanoparticles were determined, which provided mechanically strong nanopowder microgranules with a rounded shape and a homogeneous internal structure that contained no cavities. The yield of the granule fraction under 50 μm was 60%. The influence of the process parameters of the plasma treatment of the nanopowder microgranules in the thermal plasma flow on the degree of spheroidization and the microstructure of the obtained particles, seen as their bulk density and fluidity, was established. It was shown that the plasma spheroidization of the microgranules of the W-Ni-Fe system promoted the formation of a submicron internal structure in the obtained spherical particles, which were characterized by an average tungsten grain size of 0.7 μm. [ABSTRACT FROM AUTHOR]

Using citric acid, ethylene glycol, ZrOCl2·8H2O, HfOCl2·8H2O, TiCl4, NbCl5, and TaCl5 as raw materials, the (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)C high‐entropy ceramic precursor was prepared by Pechini coordination polymerization method. The precursor and pyrolysis products were analyzed and characterized by different methods. The results showed that the precursor formed a chelate structure, which greatly improved the stability of the precursor, and was clear and transparent with moderate viscosity (30–50 mPa·s). At a low pyrolysis temperature of 1600°C, single‐phase (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)C high‐entropy ceramic nanopowders with a ceramic yield of 50.8% can be obtained. The high‐entropy ceramic powder has high purity, a particle size of about 140–200 nm, and uniform element distribution. It is suitable for introduction into fiber‐reinforced ceramic matrix composite by precursor infiltration and pyrolysis (PIP) process. [ABSTRACT FROM AUTHOR]

The paper analyzes the effect of nanoadditives of zirconium dioxide, partially stabilized by Y2O3, on the Al2O3–SiO2 matrix during hot pressing by the electroconsolidation method. The microstructure obtained at different compositions and sintering modes is studied. It was established that the introduction of nanopowder ZrO2–3 mol % Y2O3 increases the crack resistance of sintered samples not only due to the transformation of the tetragonal phase to the monoclinic phase, but also due to the formation of a solid solution with aluminum oxide at the interphase boundaries. Starting from a temperature of 1400 °C, complete densification occurs with the formation of nonporous composites while preserving the nanostructure. At this temperature, the formation of mullite with cristobalite phases also begins. The high value of thermocycles makes it possible to use this composite material as a cryogenic one. The fabrication of mullite-corundum composites with additions of ZrO2–3 mol % Y2O3 nanopowders via the method of electrosolidification has enabled the attainment of high fracture toughness, K1C = 14.5 MPa⋅m1/2, and hardness HV10 = 14 GPa. These results evidence excellent mechanical properties, thereby expanding the potential applications of this material. [ABSTRACT FROM AUTHOR]

This study aims to examine the electrochemical performance of aluminum-doped cathode materials, specifically Li [Li0.20Ni0.13Co0.13Mn0.54] O2 cathode materials. Various characterization techniques, including XRD, FE-SEM, TEM, FT-IR, and EIS, were employed to analyze the resulting materials. The XRD examination revealed consistent α-NaFeO2-type structures in both undoped and doped nanopowders with aluminum. The morphology of the nanopowders remained unaffected by doping, as observed in the FE-SEM images. TEM images indicated that all the powders, irrespective of doping, exhibited a hexagonal form. Notably, Aluminum doping was found to enhance electronic conductivity and structural stability, resulting in significantly improved cycle stability, albeit with a slight decrease in starting capacity. These findings highlight the importance of carefully controlling doping levels to optimize Li-ion battery performance. [ABSTRACT FROM AUTHOR]

Abstract A simple technique was utilized to fabricate pure hexagonal La2O3 nanorods by utilizing lanthanum(III) nitrate hexahydrate (La(NO3)3·6H2O) and ammonia (NH4OH). The La2O3 nanoparticles were analyzed using XRD, TGA, Raman, SEM, FTIR, TEM, PL spectroscopy, and Mott–Schottky techniques. The XRD analysis confirmed the production of La(OH)3 nanorods under appropriate conditions, which were then successfully converted into La2O2CO3 and finally into La2O3 nanorods through annealing. The TGA analysis showed that the total weight loss was due to water evaporation and the dissolution of minimal moisture present in the environment. The FTIR analysis confirmed the presence of functional groups. The SEM analysis revealed changes in morphology. The TEM analysis to determine the particle size. The PL findings showed three emission peaks at 390, 520, and 698 nm due to interband transitions and defects in the samples. The Mott–Schottky analysis demonstrated that the flatband potential and acceptor density varied with annealing temperature, ranging from 1 to 1.2 V and 2 × 1018 to 1.4 × 1019 cm−3, respectively. Annealing at 1000 °C resulted in the lowest resistance to charge transfer (Rct).

Introduction. In our country, the use of composite materials for creating parts and structural components in the construction industry is not as widespread as it could be. Composite materials are multilayer structures made of reinforcing fibers, impregnated with a polymer binder, which is also an adhesive. The strength properties of layered structural materials are achieved through various reinforcing fillers and adhesive binders. Both glass fibre and carbon fibre fabrics and fibers themselves are widely available as layered materials. Various thermosetting resins (epoxy, phenolic, polyester, polyimide, polyamideimide, polyamide, etc.) are used as binding components. Among them, epoxy resins with high strength, wettability and adhesion to various materials are widely used. Layered composite materials (LCM) are used to make polymer reinforcement for reinforcing concrete structures, various pipes, shell frames to strengthen existing metal and reinforced concrete structures, load-bearing elements in light-loaded structures of bridges and crossings. However, at the same time they have a significant drawback – low interlayer strength (propensity to layering). As a result, the connection between the layers is disrupted, which leads to a significant decrease in the rigidity and strength of the structure. This phenomenon applies to all types of fabrics and fibers. Most often, defects in the form of layering are formed under the influence of shock loads. To improve the performance characteristics of such materials, various fillers have now begun to be used – powders (micro- and nano-sized) introduced into binder compositions. Main part. The analysis of the academic literature has shown that it is possible to increase the interlayer strength in structural elements made of LCM through the use of nanofilled binders and the introduction of nanoadditives into the interlayer space of layered materials. The article reviews the related inventions in Russia, USA, etc., which can be applied in the construction industry using nanodispersed components. With the widespread use of the presented materials (in bridges, pedestrian bridges and bridge decks, etc.), significant performance advantages can be achieved compared to materials traditionally used in the construction industry. Methods and materials. By comparing the data from the submitted patents for inventions, it was revealed that the introduction of from 2% to 5% of various nanocomponents to form a nanocomposite material provides a new means of modifying the physical properties of polymer binders. Results. It was revealed that the use of nanoparticles ensures the decrease in the fluidity of prepregs and the gelation time, and the increase in residual compressive strength and specific fracture energy – indicators characterizing the crack resistance of composite materials. As a result, fracture toughness, endurance and survivability increase. Conclusion. Increasing the reliability of composite materials leads to longer service life of products and structural elements in the construction industry

Using laser evaporation method of a target with followed condensation in a flow of buffer gas (Ar or He) the preparation of ZnSe, Fe : ZnSe, Cu : ZnSe nanopowders and their properties were studied. It is shown that for the same gas pressure (100 kPa), ZnSe nanoparticles obtained in helium have a smaller average size (11 nm), than in argon (18 nm). An increase in Ar pressure from 100 to 300 kPa led to an increase in the size of nanoparticles even further 2 times. The influence of laser radiation parameters and gas parameters on productivity of nanopowders obtaining was studied process. The nanopowders had cubic and hexagonal crystalline ZnSe phases, the content of which varied within certain limits depending on gas parameters. A comparison of theoretical and experimental data suggests that a significant part of nanoparticles were formed by desublimation of vapor directly into the solid phase. The results of the first studies of pressing and sintering of ZnSe nanopowders, obtained by laser method, are shown. [ABSTRACT FROM AUTHOR]

In the last decade, mesoporous hydroxyapatite (HA) materials have received much attention regarding environmental applications (including adsorption of soil and water contaminants, films for lithium batteries, catalysts, and support systems for catalysis) and open up ample opportunities regarding biomedical devices and structures. Molybdenum ions may strongly influence catalytic and sorption properties of materials. The present study shows an influence of hydrothermal-synthesis conditions (including temperature and duration of the treatment) on phase composition, textural properties, and morphology of molybdate-containing HA. Powders with high crystallinity manifested Brunauer–Emmett–Teller specific surface area up to 55 m2/g with a pore volume of 0.33 cm3/g. The molybdate-containing HA powders were investigated by chemical analysis, X-ray diffraction, Fourier-transform IR spectroscopy, and transmission electron microscopy. Their specific surface area, pore volume, and pore size distributions were determined by low-temperature nitrogen adsorption measurements, zeta potential was quantified, and electron paramagnetic resonance spectroscopy was performed. The concentration of MoO 4 2− preserving the one-phase state was found, and the impact of hydrothermal treatment mode was analyzed by machine learning using artificial neural networks. [Display omitted] [ABSTRACT FROM AUTHOR]

The pulsed cathodoluminescence spectra of zinc selenide at room temperature were recorded: feedstock and materials required for the synthesis of optical ceramics. Samples of the cubic phase ZnSe with stoichiometric composition were also studied in the presence of additional phases (hexagonal ZnSe and ZnO). Three characteristic luminescence bands were detected for single-phase cubic zinc selenide. For the cubic ZnSe with stoichiometric composition one strong line of interband luminescence with a width of 12–14 nm is observed in the region of 470 nm; with an excess of selenium, an additional broad band appears at 647 nm, and with an increased impurity content and a small excess of zinc a single band is observed at 588 nm. In two-phase materials containing cubic and hexagonal ZnSe as the main or additional phase luminescence is not observed at room temperature. In the spectrum of cubic ZnSe with an additional hexagonal ZnO phase, a strong broad doublet band of hexagonal ZnO appears at 525–900 nm in addition to the interband luminescence line with a wavelength that decreases from 470 to 466 nm with increasing ZnO content. A rapid analysis of the quality of the ZnSe material can be carried out on the basis of the presence or absence of these pulsed cathodoluminescence bands. [ABSTRACT FROM AUTHOR]

A nanosized powder and nanostructured fibers of nickel–zinc ferrite Ni0.5Zn0.5Fe2O4 have been synthesized. Using X-ray diffraction analysis, it has been proven that the synthesized samples correspond to the nickel–zinc ferrite phase. It has been found that the fibers based on nickel–zinc ferrite have higher crystal lattice parameter and crystallite size values than those of the synthesized nanosized powder. Scanning electron microscopy data have shown that the studied samples consist of nanosized particles with a size of 20–60 nm for the powder and 20–40 nm for the fibers. The optical diffuse reflectance method has been used to determine the band gap for the Ni0.5Zn0.5Fe2O4 samples: 1.58 and 1.67 eV for the fibers and the powder, respectively. The photocatalytic degradation of methylene blue under the action of Ni0.5Zn0.5Fe2O4 samples of the different morphologies has been studied. It has been found that the nanostructured Ni0.5Zn0.5Fe2O4 fiber sample exhibits a higher photocatalytic activity, because the degree of degradation of methylene blue is 26% for the nanofibers and 18% for the nanopowder. [ABSTRACT FROM AUTHOR]

Copyright of Iron Steel Vanadium Titanium is the property of Iron Steel Vanadium Titanium Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The study successfully produced ZnO and ZnO nanoparticles doped with transition metals (TMZO-NPs) using the co-precipitation method. Various properties of these nanoparticles were examined, including their structure, morphology, electronic behavior, optical characteristics, vibrations, and photocatalytic abilities. The analysis confirmed that all nanoparticles possessed a hexagonal wurtzite crystalline structure, with particle size being influenced by the presence of transition metals (Al, Ag, Cu, Mn). The particles exhibited a preference for orientation along the (002) axis. The shift in peak positions towards higher angles suggested that the TM might replace Zn ions in the ZnO lattice. The surface structure of the nanoparticles displayed a combination of spherical and hexagonal shapes. Further analysis identified important bands related to the stretching modes of TM-O and Zn–O bonds. The absorption properties and edges were also affected by the presence of TM. In the degradation study, both pure ZnO and TMZO-NPs were tested for their ability to break down methylene blue (MB) under UV light exposure for 90 min. Among the nanoparticles, Al-doped ZnO (AlZO-NPs) demonstrated the highest degradation efficiency, achieving 97.14% removal of MB within the given exposure time. The photocatalytic process followed a pseudo-first-order kinetics, indicating a strong correlation. This suggests that AlZO-NPs hold promise as a material for use in photocatalytic applications. [ABSTRACT FROM AUTHOR]

The nano-powders of Li (Li0.21Mn0.54Ni0.125Co0.125-x) FexO2 (x = 0, 0.025, 0.05, 0.075, and 0.1) were synthesized using a sol-gel procedure and characterized using various techniques. According to the X-ray diffraction (XRD) analysis, the patterns of both pure and Fe-doped Li-rich cathodes were in agreement with the standard reference XRD pattern of lithium nickel cobalt oxide known as α-NaFeO2-type structures. The field-emission scanning electron microscopy (FESEM) results revealed that the morphology of all the prepared samples, with or without Fe impurities, was uniform and similar. Furthermore, the particle size of nano-powders was found to be less than 100 nm and it increased with the addition of Fe impurities. The transmission electron microscopy (TEM) results showed that the particles in both pure and Fe-doped samples have an almost hexagonal shape. The addition of iron resulted in an increase in particle size. Based on the electrochemical measurements, inclusion of iron to the cathode led to the facilitated charge transfer to the cathode. The sample containing 0.075 Fe exhibited superior cyclic performance, achieving a charge capacity of 381 mAhg−1 and a discharge capacity of 353 mAhg−1 were delivered by this electrode. This sample also demonstrated the highest Coulombic efficiency among all samples, which was about 93%. [ABSTRACT FROM AUTHOR]

Abstract—A method for producing tungsten powder consisting of spherical microparticles with dimensions of 20–50 μm is considered when processing granular tungsten nanopowder in a flow of argon electric arc thermal plasma. Experimental studies of plasma chemical synthesis of tungsten nanopowder in a plasma reactor with a limited jet flow during the interaction of tungsten trioxide with a flow of hydrogen-containing plasma generated in an electric arc plasma torch were carried out. The conditions of spray drying and the properties of a suspension consisting of tungsten nanoparticles were determined experimentally, ensuring the production of mechanically strong nanopowder microgranules of rounded shape with a homogeneous internal nanostructure that does not contain cavities, with the yield of microgranules with a size of less than 60 μm at the level of 65%. The influence of the parameters of the plasma processing of nanopowder microgranules in the thermal plasma flow on the degree of spheroidization and the microstructure of the resulting particles was established. [ABSTRACT FROM AUTHOR]

The main directions and fields of the application of metal nanopowders in joining technologies are considered. Based on this analysis, the purpose of this research was to determine the effect of tungsten nanopowder on the structure and properties of the deposited metal. In order to increase the efficiency of using tungsten nanopowder for modification, it is necessary to ensure the introduction of nanopowder into the low-temperature zone of the molten metal during surfacing. To study the metal, microstructural analysis was performed, and the microhardness of the deposited joint was determined. On the basis of the conducted studies, a change in the structure of the deposited metal and an increase in mechanical properties were revealed. A conclusion is made about the effect of tungsten nanopowder on the metal modification process during manual metal arc, metal inert gas, and flux-cored arc welding. Based on the conducted studies, it was found that the introduction of tungsten nanopowder into the low-temperature zone of the molten metal ensures the modification of the surfacing and induces an increase in the microhardness of the deposited metal. At the same time, grains of polyhedral morphology are formed at the surface, and the structure of oriented dendrites at the boundary of fusion with the base metal is also revealed, showing the peculiarities of the distribution of microhardness in various surfacing methods. The minimum and maximum values of microhardness depend not only on the nanopowder but also on the method of its introduction into the molten metal.

Objective. The purpose of the study is to experimentally measure the surface energy of solids during their grinding.Method. The study is based on the use of methods for determining the surface tension of solids. At least 20-25% of all electricity produced in the world is spent on grinding materials in industry. When the resulting particles are reduced to tens of nanometers, the contribution of surface energy (st) to the grinding work becomes so large that it is difficult not to take it into account. Measuring the surface tension of liquids has long been proven. But measuring (st) of solids causes great difficulties. Currently, more than twenty methods for determining (st) are known.Result. Based on the phenomenon of spontaneous bending of thin thread-like structures, a method for determining (st) has been developed. Examples are given in which (st) at the phase interface plays an important role in obtaining samples with a microstructure using the method of severe plastic deformation (SPD). To obtain fine metal powders, one of the variants of the SPD method has been proposed. A method has been found for the physical activation of aluminum granules, which increases the reaction rate of the metal in an aqueous environment by about a thousand times. This is necessary for the development of an anaerobic power plant capable of operating at great depths.Conclusion. The new technology makes it possible to obtain high-purity, non-oxidized metal powders without toxic waste and emissions and with energy costs lower than in all known methods.

A three-part tape-enhanced tube was used in the current hypothetical solar unit to save the most radiation possible. The three parts were joined at different angles (β). The parameters of the carrier base fluid after mixing with CuO nanopowder were calculated using a homogeneous model. By adjusting the range of Y + , multiple layers were used to precisely depict the behavior of flow close to the wall. The results show the components of irreversibility as bar charts, velocity contours, and exergy drop contours. The tape angle (β) and inlet velocity were thought to be the main driving forces. An evaluation of the accommodation's validity using numerical data shows that it is sufficient. The wall temperature decreases by about 0.0257% as the nanofluid angle rises and more collisions with the wall take place. Xd falls off roughly 5.19% from 0∘ to 45∘ and 5.87% from 0∘ to 90∘ as the angle β rises. As β rises, the entropy of friction increases by 9.88%. The outer wall cools by about 0.87% and Xd falls by about 92.3% when β = 4 5 ∘ and Re rises. [ABSTRACT FROM AUTHOR]

The morphology and degree of agglomeration of the precursor and YAG-ceramic powders were investigated as functions of the grinding conditions, followed by an assessment of the influence of these parameters on the optical properties and structure of the ceramic. YAG-precursor powders were obtained by chemical coprecipitation. The morphology and size of the agglomerates and crystallites were assessed by means of scanning electron microscopy, laser diffraction analysis, x-ray diffraction analysis, and Brunauer–Emmett–Teller gas adsorption. It was discovered that grinding of the YAG precursor powders can decrease the degree of agglomeration of the ceramic powder. It was found that with a mass ratio of grinding balls to precursor powder of 6.75/1 and a mass ratio of the grinding medium to the mass of the precursor powder of 4.5/1, optimal conditions obtain for providing the necessary granulometric characteristics and the highest mono-dispersity. In summary, by such means the properties of YAG optical ceramic can be improved by using of an additional grinding stage for the powders synthesized by chemical deposition and by selecting suitable grinding modes. [ABSTRACT FROM AUTHOR]

Sb2S3 chalcogenide Nanopowder was prepared at low temperatures using the chemical co-precipitation method. PVA/PVP polymeric sheets have been prepared with a constant ratio of 2:1 as a host matrix to incorporate Sb2S3 NPS with a ratio of 0, 1, 3, and 5 wt% via solution casting technique. The X-ray diffraction (XRD) pattern revealed that the prepared Sb2S3 powder belongs to an orthorhombic crystalline structure as a major phase, with a crystal size of 24 nm. The microstructure of the powder as well as 5 wt% Sb2S3/PVA/PVP was investigated using the transmission electron microscope. The Fourier transform infrared spectra of the prepared sheets revealed the success of the interaction between the filler Sb2S3 material with the PVA/PVP as a polymer host matrix. The transmission and reflection spectra of the polymeric Sb2S3 /PVA/PVP sheets measured in the wavelength range 200–2500 nm have been used to calculate the optical band gap energy and refractive index as a function in the Sb2S3 wt%. The Tauc model and the absorption spectrum fitting model were employed to accurately determine the variation of the optical band gap value with Sb2S3 filler percent. Wemple-DiDomenico single-oscillator and Spitzer-Fan, models were applied to analyze the refractive index as a function of the Sb2S3 filling wt%, whereby the dispersion parameters, E d , E o as well as the optical high-frequency dielectric constant, ε L carrier concentration to the effective mass ratio, N / m ∗ were evaluated. A graphical representation of the optical conductivity was also present. The obtained data indicate the possibility of using the prepared Sb2S3/PVA/PVP nanocomposite sheets for optoelectronic applications and optical devices. [ABSTRACT FROM AUTHOR]

Multiphase nanomaterials are of increasing importance in material science. Providing reliable and statistically meaningful information on their average nanostructure is essential for synthesis control and applications. In this paper, we propose a novel procedure that simplifies and makes more effective the electron powder diffraction-based Rietveld analysis of nanomaterials. Our single step in-TEM method allows to obtain the instrumental broadening function of the TEM directly from a single measurement without the need for an additional X-ray diffraction measurement. Using a multilayer graphene calibration standard and applying properly controlled acquisition conditions on a spherical aberration-corrected microscope, we achieved the instrumental broadening of ±0.01 Å in terms of interplanar spacing. The shape of the diffraction peaks is modeled as a function of the scattering angle using the Caglioti relation, and the obtained parameters for instrumental broadening can be directly applied in the Rietveld analysis of electron diffraction data of the analyzed specimen. During peak shape analysis, the instrumental broadening parameters of the TEM are controlled separately from nanostructure-related peak broadening effects, which contribute to the higher reliability of nanostructure information extracted from electron diffraction patterns. The potential of the proposed procedure is demonstrated through the Rietveld analysis of hematite nanopowder and two-component Cu-Ni nanocrystalline thin film specimens. [ABSTRACT FROM AUTHOR]

The possibility of measuring the degree of fixing (pinning force) of domain walls in cobalt nanowires by the NMR spin-echo method under the action of an additional magnetic video-pulse on a two-pulse echo is demonstrated. This method can be used for NMR estimation of the pinning force of domain walls and the coercive force of cobalt nanowires to optimize their chemical synthesis in an external magnetic field for potential use in rare-earth-free permanent magnets, sensors, and other applications. [ABSTRACT FROM AUTHOR]

Investigation of the processes involved in the synthesis of magnesium oxide and zinc oxide powders using the thermal effects of an atmospheric-pressure glow discharge plasma in an inert gas flow are described. The discharge operates in a repetitively pulsed mode with pulse repetition rate of several tens of kilohertz and pulse duration up to 12 μs, discharge current of 600 mA and voltage up to 300 V. These parameters lead to thermal erosion of magnesium or zinc inserts in a molybdenum crucible. The chemical and phase composition of the erosion products were determined using TEM/EDS and X-ray diffraction analysis, and the composition of the plasma was assessed by optical emission spectrometry. This experimental approach allows fabrication of powders of these metal oxides with characteristic particle size 10–50 nm, and the formation of coatings of these materials in a one-step process. [ABSTRACT FROM AUTHOR]

Peculiarities of sintering of foamy ceramic filters based on submicron aluminum oxide powders with additions of titanium oxide and manganese dioxide nanopowders are considered. The processes of removal of polymeric and binder paraffin material during sintering have been studied. The physical and mechanical properties of the obtained porous permeable filters with a foamy structure were analyzed in details. At a sintering temperature in an air atmosphere of 1350 °C, sufficiently high physical and mechanical properties were obtained, which made it possible to use the developed filters as catalyst carriers for vehicle exhaust gases. Bench comparative tests have shown that ceramic filters with a foamed structure are promising catalysts for afterburning car exhaust gases instead of ceramic honeycomb blocks of catalyst carriers. The developed technology allows reducing the sintering temperature of porous foam ceramic filters to 1350 °C and replacing expensive high-temperature ceramic heaters with cheaper nickel-chromium ones. [ABSTRACT FROM AUTHOR]

The dependence of the resistance of basic refractories to high-temperature plastic deformation under load on the amount of zirconium dioxide modifying additive is reported. Creep curves are presented and analyzed. ZrO2 nanoparticles (average particle size 100 nm) were added to the composition in the range 0.25 – 0.75 wt %. The resistance to high-temperature plastic deformation was significantly improved and was due to the interaction of the ZrO2 additive with CaO contained in the synthetic periclase obtained by precipitation. Increasing the amount of ZrO2 additive above 0.5 wt % was found not to have a significant effect. [ABSTRACT FROM AUTHOR]

This article presents a detailed study on the electrochemical synthesis, analysis, and potential applications of nanoparticles composed of zinc oxide (ZnO) and zinc sulfide (ZnS); the electrochemical method of obtaining ZnO/ZnS nanoparticles from a solution using two-electrode synthesis and zinc anodization is described. Sodium chloride and thiourea were used as the electrolyte; the concentration ranges of sulfur-containing substance was investigated, under which only zinc sulfide can be obtained. The influence of thiourea concentration on the particle thickness and composition of the electrolysis products in an aqueous solution of sodium chloride with a soluble zinc anode was studied for the first time. X-ray diffraction was employed to analyze the structural properties and thickness of the nanoparticles. The products of zinc anodization are nanoscale zinc oxide and zinc sulfide. With an increase in the thiourea content, the thickness of the formed particles decreases. It was found that at the lowest thiourea concentrations, mainly zinc oxide is formed, while at the highest concentrations, mainly zinc sulfide is formed. Increasing the concentration of thiourea is accompanied by the transformation of the wurzite modification of ZnO into sphalerite and the substitution of oxygen atoms with sulfur atoms. ZnS particles (1.3-3.6 nm) are significantly thinner than ZnO particles (7-29 nm). The synthesized nanoscale powders of zinc oxide, zinc sulfide, and their mixtures can be used for the production of semiconductor devices. The article discusses the potential applications of these nanoparticles in various fields such as photocatalysis, sensors, and energy storage devices. Overall, this study provides valuable insights into the synthesis, characterization, and potential applications of ZnO/ZnS nanoparticles, highlighting their promising prospects in nanotechnology. [ABSTRACT FROM AUTHOR]

Discharges with cathode spots can operate in a wide range of gas pressures. Erosion of the cathode material is an inherent property of such discharges. The erosion products are considered to be ionized atoms and electrically neutral microdroplets. In accordance with this concept, a plasma source based on a pulsed cathodic arc discharge in atmospheric-pressure argon with a current of up to 200 A, a pulse duration of 250 μs, and a pulse repetition rate of 10 Hz was implemented. Using this source, the synthesis of magnesium oxide powder was performed. The chemical composition of the erosion products was determined using the TEM/EDS method and the composition of the gas mixture in which the discharge system operated was evaluated by optical spectrometry. It was shown that particles of the synthesized powder have different morphological features, depending on the nature of the electrical erosion of the cathode material. Micron-sized particles are formed due to the removal of microdroplets from liquid–metal craters on the cathode surface at certain plasma pressures. Submicron particles are produced during the agglomeration of atoms originating from the plasma jets flowing out from cathode spots. These atoms are magnesium ions that are neutralized by collisions with gas particles. The advantages and disadvantages of this synthesis method are discussed in this paper. The reference methods for the powder synthesis of magnesium oxide are compared. The prospects of the studied method from the point of view of its application for obtaining ceramic materials are also evaluated.

Precipitation of nanopowders with mixed magnetite–maghemite composition was carried out under different conditions and with different separation techniques. The exact character of interactions of different iron oxide phases in the nanopowder was the main object of interest. The obtained nanopowders have spherical particles about 10–20 nm in size. Electron paramagnetic resonance (EPR) study showed that iron ions incorporate fully into magnetite and maghemite structures. The shape of the EPR line points out that single homogenous solid solutions were formed during synthesis. In the studied solid solutions, different ratios of vacancies and Fe2+/Fe3+ ratios were observed but in spite of different synthesis techniques in both cases, there were no additional diamagnetic structural phases presented.

The synthesis of the nanopowders of magnesium oxide and magnesium fluoride during the operation of a repetitive diffuse nanosecond discharge in argon at various pressures was performed. Nanosecond voltage pulses with an amplitude of −70 kV, a rise time of 0.7 ns, and a duration of 0.7 ns were applied across a point-to-plane gap of 2 mm in length. The pulse repetition rate was 60 Hz. The high-voltage pointed electrode was made of magnesium. A diffuse discharge cold plasma was formed under these conditions. Nanoparticles were produced as a result of an explosion of microprotrusions on the surface of the magnesium electrode duo to a high current density. Lines of magnesium atoms and ions were observed in the emission optical spectrum. Under the actions of the gas dynamics processes caused by the plasma channel expansion during the interpulse period, nanoparticles were deposited onto the surface of the grounded plane electrode and the side wall of the gas discharge chamber. The morphology, elemental, and phase composition of the powders were studied using transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS).