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The isothermal oxidation behavior of multi-component high entropy alloys (HEAs), namely AlCuCrFeMn, AlCuCrFeMnW0.05, AlCuCrFeMnW0.1, and AlCuCrFeMnW0.5, was investigated and the behavior of the oxide layer was analyzed. All four HEAs were synthesized via mechanical alloying (MA) and consolidated by spark plasma sintering (SPS). The samples were oxidized in the air atmosphere at a temperature of 500 °C for 50 h. Based on the thermogravimetric result, the oxidation rate of the materials decreased with the increase of W content, and the values of parabolic constants were on a level similar to those observed in Ni–Al superalloys. However, higher content of W improves the continuity and internal position of the WO3 scale, which leads to increased oxidation resistance. Throughout the oxidation process, the composition of the phases of all materials changed significantly. The triple-thick oxide layer formed of Al2O3, Cr2O3, and WO3, developed in HEAs, has been carefully studied using the XPS technique.

In this article, we present a new Co2FeSi glass-coated microwire obtained by Taylor-Ulitovsky technique with nanocrystalline structure consisting of a mixture of bcc phase (lattice parameter, a = 5.640 Å, crystalline grain size, Dg = 17.8 nm) in as-prepared sample. The annealing temperature was fixed at 873 K, and the annealing time was 1 and 6 h. The annealing resulted in a significant increase of such nano-grains up to (31.6 nm). Perfect square hysteresis loops have been observed in all annealed samples at a wide temperature range (55–400 K) that are not seen in the as prepared sample. The thermal magnetic behavior for the annealed samples shows dramatic magnetic behavior at low temperature. Large irreversibility magnetic behavior with a blocking temperature (Tb = 150 K) has been observed for annealed sample for 1 h. Critical temperatures of 155 K and 105 K have been detected for annealed samples for 1 h and 6 h, respectively, where the behavior of M−H loops, coercivity and remanence changed. Below the critical point the M−H shows wasp-waisted, multistep magnetic behavior and complex magnetic reversal mechanism is supposed. The anomalous magnetic behavior is due to the coexistence of the ordered and disordered phases induced by annealing conditions below the room temperature. The difference in the magnetization behaviour, remanence, and coercivity values for Co2FeSi glass-coated microwires samples indicates the influence of internal stresses created by the presence of the glass coating. These finding opens the door to design spintronic devices based on the magnetization switching.

High-frequency transformer core materials are used in power converter applications due to high efficiency performance. Their volume and weight can be reduced when higher operating frequencies are used but at the expense of an increase in core material losses. Some studies analyzed transformer core material performance by using finite element method (FEM) analysis, while others used an experimental model. This study proposes an experimental approach to compare the high-frequency transformer efficiency performance of different core material types. In this way, newly produced core material performance can be rapidly analyzed by comparing it against a known core material type, thereby resulting in the fast identification of improved core material design. This empirical approach makes use of a standard half-bridge inverter topology to enable an analysis of high-frequency transformer core material efficiency performance. Actual voltage and current measurements are used to determine the efficiency and output power performance throughout a specified constant current load range at different switching frequencies. Initially commercial standard polycrystalline or ferrite E-core materials were used to validate the characterization jig performance measured curve trends. The usefulness of the jig is then demonstrated by comparatively analyzing and then verifying the expected performance difference between polycrystalline and nanocrystalline toroidal core materials. [ABSTRACT FROM AUTHOR]

The present work is focused on the eco-friendly electrodeposition of nanocrystalline palladium on the copper substrate using an ammonia complex for the replacement of gold. The detailed study on the electrodeposition of palladium prepared from ammonia complex and solution characteristics such as current efficiency and thickness of the film growth per hour was evaluated using Faraday's law of electrolysis, and the quality of the deposits was observed by Field Emission Scanning Electron Microscopy (FESEM). The crystal structure orientation of the crystal and lattice parameters were analysed by X-ray diffraction and crystal sizes were calculated using the Debye–Scherrer equation. The deposits produced from gelatin-containing electrolyte showed the lowest crystal size which indicates that grain refinement was assisted by additives. The microstructures of the palladium deposits were determined by FESEM and the surface morphology of the palladium deposits was evaluated using AFM. The elemental composition and oxidation state of the palladium deposits were investigated by XPS. These results revealed the presence of additives giving smooth uniform homogenous surface morphology. Hence, gelatin served as a grain modifier. [ABSTRACT FROM AUTHOR]

Nanocrystalline metals have presented intriguing possibilities for use in radiation environments due to their high grain boundary volume, serving as enhanced irradiation-induced defect sinks. Their promise has been lessened due to the propensity for nanocrystalline metals to suffer deleterious grain growth from combinations of irradiation and/or elevated homologous temperature. While approaches for stabilizing such materials against grain growth are the subject of current research, there is still a lack of central knowledge on the irradiation–grain boundary interactions in pure metals despite many studies on the same. Due to the breadth of available reports, we have critically reviewed studies on irradiation and thermal stability in pure, nanocrystalline copper (Cu) as a model FCC material, and on a few dilute Cu-based alloys. Our study has shown that, viewed collectively, there are large differences in interpretation of irradiation–grain boundary interactions, primarily due to a wide range of irradiation environments and variability in materials processing. We discuss the sources of these differences and analyses herein. Then, with the goal of gaining a more overarching mechanistic understanding of grain size stability in pure materials under irradiation, we provide several key recommendations for making meaningful evaluations across materials with different processing and under variable irradiation conditions. [ABSTRACT FROM AUTHOR]

In this study, Al85Ni5Fe5Nd5 (at.%) alloy was produced as thin ribbons by rapid solidification method and as powders by mechanical alloying method. The structural properties of the alloys such as morphological properties, phase identification, particle size and distribution of particles were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Thermal properties of the alloy such as crystallization temperatures, activation energy and phase transformations were investigated by differential scanning calorimetry (DSC). The ribbons produced by the rapid solidification method were obtained in amorphous structure, and the powders produced by mechanical alloying were obtained in nanostructure. The XRD results showed that after 200 h of alloying process, the crystal size of the powder alloys decreased below 15 nm and nanostructured phases such as Al3Ni and Al18Nd3 were formed. The activation energy of the amorphous alloy was calculated by the Kissinger method. The activation energy for the initiation temperature of the first crystallization peak was calculated as 482 kJ/mol. This study showed that rapid solidification method is suitable for producing amorphous alloy and mechanical alloying method is suitable for producing nanocrystalline alloy. [ABSTRACT FROM AUTHOR]

To improve the electrochromic (EC) properties of sol–gel-derived WO3 films, a series of organic small molecules, such as dopamine (DA), catechol, tyramine, phenol and 2-phenylethylamine, were added into peroxotungstic acid precursor sols as structure-directing additives, and five modified WO3 films were prepared by a simple and low-cost complexation-assisted sol–gel method. The effects of the above additives on the EC properties of the modified WO3 films have been studied in detail. Compared with the pure WO3 polycrystalline film, all the modified films combine the advantages of nanocrystalline and amorphous phases and show higher EC properties attributed to the unique nanocrystal-embedded amorphous structure. The results indicate that different additives with different numbers and types of functional groups (hydroxyl and amino groups) can change the microstructure, morphology, and thus electrochemical and EC properties of the films in various degrees. The additives, in order of their strong interactions with the sols, are DA, catechol, tyramine, phenol and 2-phenylethylamine, primarily depending on the number of hydroxyl groups. Of all the additives, DA with both catechol hydroxyl and amino groups shows the most positive effect; that is, the WO3 film modified with DA exhibits the best EC properties in terms of contrast, switching speed, stability, and coloration efficiency. [ABSTRACT FROM AUTHOR]

A study using a pulsed laser deposition (PLD) technique was accomplished by growing NiTi nanoparticles on glass and stainless steel 316L substrates. The effects of laser energy state of deposition on the granule size of the NiTi nanoparticle and the structural properties of its thin film were discussed. X-ray diffraction analyses revealed that the films prepared at 65 W, 75 W, 85 W, 100 W exhibited amorphous structures. AFM results confirmed that the thin films consist of evenly distributed spherical particles. The results also showed an exponential increase in those particles' sizes. [ABSTRACT FROM AUTHOR]

A deep reddish-orange-emitting Sm3+-activated vanadate-based nanocrystalline material series is developed via the solution combustion procedure. A trigonal crystal framework is formed with space group R3c (161) having unevenly designed particles with extents between 33 nm and 62 nm. Morphological aspects are examined via scanning and transmission electron microscopy (SEM and TEM). The elemental investigation is confirmed through energy-dispersive x-ray analysis (EDAX). On near-UV excitation, the luminescence spectrum presents a fair reddish-orange emission at 606-nm wavelength consistent with the electronic transition 4G5/2 → 6H7/2. The energy band gap is inspected via diffuse reflectance measurements. Radiative lifetime, quantum efficacy, and rates of radiation-less transformations were also examined and found to have values as 1.4914 ms, 82.84%, and 115.1 ms−1 for the optimized nanosample, respectively. The CIE coordinates, and hence CCT values, lay in the reddish-orange zone of the chromaticity plot, thus finalizing their potential application in WLEDs, solid-state lighting (SSL), and other advanced optoelectronic applications. [ABSTRACT FROM AUTHOR]

In this work, various emerging core and winding materials suitable for a high frequency planar transformer (PT) has been analyzed and compared. Core and winding materials used in a transformer has a significant effect mostly in the core and winding losses of the transformer. Emerging core materials like amorphous and nanocrystalline cores were compared against the conventional ferrite core. The results obtained showed that core losses were reduced by around 48.14% on using amorphous or nanocrystalline cores instead of the conventional ferrite cores. Typical copper and aluminum windings were also compared with emerging materials like carbon nanotube (CNT), Cu/CNT and Al/CNT. Winding losses was found to be the lowest on using CNT windings instead of metal windings like Cu or Al, or metals composite windings like Cu/CNT and Al/CNT. A winding loss reduction of about 56.2% was seen with CNT windings. Thus, it was concluded that the best possible core and winding combination was amorphous or nanocrystalline cores with CNT windings, as they give the lowest possible core and winding losses for the PT. Finite Element Analysis was carried out on a 2-kW PT operating at 100 kHz frequency, with the software Altair FLUX for the analysis. [ABSTRACT FROM AUTHOR]

Rapid industrial growth causes considerable environmental havoc, adversely affecting human and aqueous life. It becomes a significant concern to deal with adequate wastewater treatment strategies by converging on water scarcity. This research work explored the synthesis of titanium-substituted Y-type barium hexaferrite (Co2-Y), having a general formula of Ba2Co2Fe12-xTixO22 (x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5), using a facile nitrate-based sol–gel auto-combustion route and its suitability was investigated as a heterogeneous catalyst within the photo-Fenton-based degradation of methyl orange (MO), one of the significant pollutants generated from textile industries. Developing a thermochemically stable and magnetically separable heterogeneous catalyst for photocatalytic decomposition of nonbiodegradable organic dye from wastewater was also emphasized. The as-prepared nanocrystalline Co2-Y powders were analyzed using XRD, FTIR, DLS, UV–visible spectroscopy, SEM, VSM, and XPS. Furthermore, the photocatalytic degradation performance of pristine and titanium substituted Ba2Co2Fe11.6Ti0.4O22 ferrite, having the lowest bandgap value among all samples, was quantified and compared in terms of apparent rate constant (karc) value and turnover frequency values. The enriched photocatalytic performance was correlated with the existence of multi-valance states of transition metal cations and the availability of oxygen vacancy, confirmed by the surface chemistry using the XPS analysis. The modified (enhanced thermal and chemical stability) hexaferrite catalyst was magnetically separable and reusable without significant losses to its catalytic performance. This promising catalyst may be considered as a replacement for soft ferrite materials to catalyze the degradation of several other nonbiodegradable organic pollutants from wastewater in large-scale industries. [ABSTRACT FROM AUTHOR]

The hydrogen evolution reaction (HER) electrocatalytic activities normalized to electrochemically active surface area (ECSA) were systematically evaluated and correlated with its composition (i.e., Mo content up to 26 at. %), crystal structure (i.e., face-centered cubic (fcc) to orthorhombic phase and the mixed phases with different phase ratios), and crystallinity. The electrodeposited with mixed phases exhibited highest ECSA (up to 228 cm2 per 1 cm2 geometric surface area) compared to deposits with single phase, which serves as the dominant factor to enhance exchange current density and overpotential. Low overpotentials per ECSA were observed with Mo content of 5.16 at% (fcc) and 24.1 at% (mixed phases). After normalizing with ESCA, The Tafel slope and exchange current density were indifference with Mo content, crystal phase, and grain size. The metallic Ni–Mo thin films have low mixed potential and overpotential at 10 mA/cm2 of 20 mV and 120 mV, respectively. • Ni–Mo with different composition, and crystal structure were electrodeposited. • Mixed crystal phases resulted in highest electrochemically active surface area. • Mixed phases Ni–Mo electrodeposits also show to enhance exchange current density. [ABSTRACT FROM AUTHOR]

A nanocrystalline CrMnFeCoNi high-entropy alloy produced using severe plastic deformation using high-pressure torsion was annealed at selected temperatures and times (450 °C for 1 h and 15 h and at 600 °C for 1 h), causing a phase decomposition into a multi-phase structure. The samples were subsequently deformed again by high-pressure torsion to investigate the possibility of tailoring a favorable composite architecture by re-distributing, fragmenting, or partially dissolving the additional intermetallic phases. While the second phase in the 450 °C annealing states had high stability against mechanical mixing, a partial dissolution could be achieved in the samples subjected to 600 °C for 1 h. [ABSTRACT FROM AUTHOR]

In this study, a combined process of reduction and adsorption for the degradation of azo dye with nanocrystalline Fe80Si10B10 powder as a reducing agent is analyzed. A mechanical alloying technique produced the powdered alloys needed for the redox process. The synthesized nanocrystalline structure favors the efficiency of the reduction step of Reactive Black 5 (RB5) azo dye. According to the UV-Vis analysis, the reductive process alone allowed for nearly complete color removal after 3 min of reaction. In this regard, the nanocrystallized FeSiB powder has excellent application potential in the first step of the reduction processes for degrading azo dye solutions. Indeed, the nanocrystalline FeSiB powder outperforms commercial Fe powders in terms of degradation efficiency because of the formation of multiple micro-batteries between the α-Fe solid solution and the Fe3Si nanocrystalline phases, favoring the loss of electrons from iron and exhibiting different corrosion resistance. In the second step, the adsorption process, the efficient removal of intermediate undesired compounds from the reduction processes, principally aromatic amines, is analyzed. Different adsorbents, including wood, graphene oxide, activated carbon, and pine particles, were used. The results suggest that graphene oxide and activate carbon performed the best for secondary product adsorption following RB5 degradation. The current study could serve as a guide for environmental applications, such as industrial wastewater treatment, using metallic powders produced by high-energy mechanical alloying. [ABSTRACT FROM AUTHOR]

In this study, the wear resistance of two high-Mn austenitic steels, i.e., Fe−18.5Mn−7Cr−0.6C and Fe−18.5Mn−7Cr−0.6C−0.21N was tested in dry sliding friction on a disc friction and wear testing machine (MMU-5G). The wear behavior and microstructure evolution of the two tested steels were investigated. The results revealed that adding N enhanced the wear resistance of high-Mn austenitic steel due to the synergistic effects of hardness, wear hardening, and oxide layer. Interstitial N atoms increased the matrix hardness and decreased the stacking fault energy (SFE). The lower SFE facilitated wear hardening, and the active mechanical twins along with the higher dislocation density induced the formation of a thicker nanocrystalline layer with finer grains. The nanocrystalline layer with higher surface activity promoted the adsorption of a protective oxide layer. These factors decreased the surface roughness, coefficient of friction (COF), and wear rate of N-alloyed high-Mn austenitic steel. This study provided valuable insights into the application of N-alloyed high-Mn austenitic steels under dry sliding friction conditions. • Adding N improved dry sliding wear resistance of high-Mn austenitic steel due to hardness, wear hardening, and oxide layer. • Interstitial N atoms increased the matrix hardness and decreased the stacking fault energy (SFE). • The lower SFE facilitated wear hardening, then induced the formation of a thicker nanocrystalline layer with finer grains. • The nanocrystalline layer with higher surface activity promoted the adsorption of a protective oxide layer. [ABSTRACT FROM AUTHOR]

[Display omitted] • A magnetic noise calculation method considering anisotropy is proposed. • An anisotropic electromagnetic parameter calculation method is proposed. • Simulations and measurements of magnetic noise verify the accuracy of the model. • The trend of magnetic noise within 1–30 Hz is quantitatively analyzed. Nanocrystalline magnetic shielding devices can provide a low-noise test environment for magnetoencephalography (MEG) measurements. Its unique interlayer insulation structure effectively impedes eddy currents, improves eddy current losses, and reduces magnetic noise. Due to nanocrystalline materials' laminated structure and anisotropy, we propose innovative equivalent electromagnetic parameter models encompassing anisotropic equivalent conductivity and permeability. Magnetic noise calculations and experiments have been conducted on nanocrystalline magnetic shielding devices under near-zero magnetic fields, resulting in an error rate of only 3.11 %, verifying the effectiveness of the proposed model. In addition, we have explored the changing law of permeability of nanocrystalline materials under different stacking factors and quantitatively analyzed the magnetic noise trend in the low-frequency range of 1–30 Hz. This study advances magnetic shielding technology for ultrahigh-sensitivity atomic sensors, enhancing their overall performance and precision. [ABSTRACT FROM AUTHOR]

This work explores the possibility of manufacturing dense and nanocrystalline hydroxyapatite (HA) large monoliths by spark plasma extrusion (SPE). This method combines uniaxial mechanical compression, high temperature, and electromagnetic field to promote the extrusion and sintering of HA powder in one single step. The results show that the binder-free extrusion of pre-compacted HA powder is feasible at a temperature similar to the temperature at which nanocrystalline HA shows superplastic behavior. The extrusion continues throughout the sliding and rotation of the particles, and also due to the grain boundary sliding, up to the point where no more material is available, thus producing monoliths of nearly 30 mm in length and 10 mm in diameter. The dehydration and smooth surface of the powder appear as paramount factors to facilitate the HA extrusion without additives. The extruded HA preserved the stoichiometry and nanometric grain size and exhibited preferential microstructural alignment in the direction of extrusion. The material experiences local thermal and pressure gradients during extrusion, producing different densification and hardness along its length. The SPE of HA will benefit the healthcare field by offering new processing approaches of bone substitutes and osteosynthesis devices.

[Display omitted] • No temperature-induced phase transition occurs in NiTi alloy with GS below 10 nm. • There exists OWSME in nanocrystalline NiTi alloy with GS lower than 10 nm. • Physical mechanism for OWSME in NiTi alloy with GS below 10 nm is revealed. • OWSME in alloy with GS below 10 nm is aroused by retained stress-induced martensite. In the present work, a novel finding is that nanocrystalline NiTi alloy with ultrasmall-sized grains (where the diameter of grains is less than or equal to 10 nm) presents one-way shape memory effect (OWSME) without temperature-induced phase transformation, where the involved physical mechanism is revealed by combining experiments with molecular dynamics simulation (MD). The results show that fraction of grain boundaries (GBs) is so much that temperature-induced martensitic transformation is suppressed, but it leads to a certain unrecoverable strain. The following loading results in increase of strain and decrease of Gibbs free energy, which leads to stress-induced martensitic transition. After unloading, Gibbs free energy is increased by the release of elastic strain, which leads to partial reverse martensitic transition. Consequently, OWSME in nanocrystalline NiTi alloy with ultrasmall-sized grains is aroused by retained stress-induced martensitic transition followed by its reverse phase transition rather than temperature-induced one followed by its reverse phase transition. [ABSTRACT FROM AUTHOR]

• MPCVD was used to grow polycrystalline diamond (PCD) films in H 2 -CH 4 -N 2 gas mixtures with substrate temperatures of 700–1050 °C. • Nitrogen (N 2) additions even at concentrations <1% still affect the structure and phase composition of the grown PCD films. • The effect of N 2 concentration and substrate temperature on the grain size, roughness and sp2/sp3 ratio in the grown PCD films is demonstrated. • The particular conditions of the transition from microcrystalline (MCD) to nanocrystalline (NCD) type of growth were established. • The minimal surface roughness and maximal growth rate of NCD films occurred at N 2 concentration of 0.2–0.5 % and T ≈ 850–900 °C. This research explores the complex influence of nitrogen concentration and substrate temperature on the resultant properties of polycrystalline diamond (PCD) films grown by microwave plasma chemical vapor deposition (CVD). In particular, we investigated the growth parameters to find the exact conditions for changing the morphology of the resulting film from microcrystalline (MCD) to nanocrystalline (NCD). A series of 2 µm-thick polycrystalline diamond films was grown on Si substrates in methane-hydrogen–nitrogen gas mixtures with varied: (i) nitrogen concentration (0–2 %) and (ii) substrate temperature (700–1050 °C). Comprehensive characterization techniques, including scanning electron microscopy (SEM), micro-Raman spectroscopy, and X-ray diffraction, were employed to assess the morphological, structural, and spectroscopic properties of the films. The study reveals that even minor additions of nitrogen significantly modulate secondary nucleation, impacting both film morphology and phase composition. Furthermore, substrate temperature emerges as another critical parameter, influencing the growth kinetics and crystallite size. The comparison of the characteristics of grown PCD films allowed us to find conditions for the formation of NCD films with minimal surface roughness and maximal growth rate: nitrogen concentration [N 2 ] ≈ 0.2–0.5 % and temperature T ≈ 850–900 °C. These findings can be used to optimize the CVD synthesis parameters of PCD films for applications as protective or friction-reducing layers, as well as for superhard cutting tools and optical devices. [ABSTRACT FROM AUTHOR]

The LiNi 0.33 Mn 0.33 Co 0.33 O 2 compound is a cathode material for Li-ion batteries. Li diffusion in this material directly influences charging/discharging times, power densities, maximum capacities, stress formation and possible side reactions. In the present study, Li tracer self-diffusion is investigated on ion-beam sputtered films after deposition (amorphous) and after crystallization at 700 °C. For the experiments, 7Li isotope enriched films with about 1.5 μm thickness were combined with a 50–90 nm thick 6Li tracer layer with the same chemical composition. Afterwards, the films were diffusion annealed between 100 and 300 °C. For analysis secondary ion mass spectrometry in depth profile mode was applied. The diffusivities of the crystalline films are identical to those of sintered bulk samples within error limits as known from literature and show an activation enthalpy of diffusion about 0.9 eV. In contrast, the diffusivities of the amorphous films are about one order of magnitude lower at 100 °C due to a higher activation enthalpy of diffusion of 1.1 eV. We attribute this higher activation enthalpy to a hindered diffusion in the amorphous state of the two-dimensional ion conductor. • The Li tracer diffusivities of LiNi 0.33 Mn 0.33 Co 0.33 O 2 crystalline thin films and sintered bulk materials are identical. • The diffusivities of amorphous films are lower due to a higher activation enthalpy of 1.1 eV instead of 0.9 eV • The higher activation enthalpy is attributed to a hindered diffusion in the amorphous state. [ABSTRACT FROM AUTHOR]

This article proposes a simulation model of single-phase common-mode inductors to evaluate the small-signal characteristic of common-mode inductors when the stray capacitance cancellation method is applied. From the estimated stray capacitance of common-mode inductors, the value of the cancellation capacitors is determined and implemented into the model. Thus, the proposed model can simulate the small-signal characteristic of common-mode inductors with the capacitance cancellation method at the design stage. To validate the proposed model, a comparison between measured and simulated attenuation characteristics of fabricated single-phase common-mode inductors is performed. The comparison result clarifies that the high-frequency attenuation improvement of the capacitance cancellation method is limited for manganese–zinc ferrite-based common-mode inductors due to the steep change of the complex permeability.

The paper presents an analysis of the results of a study into diamond-like carbon films synthesized by plasma-chemical deposition from hydrocarbon sources: methane (СН4) and ethane (С2Н6). Analysis of the spectra of X-ray photoelectron spectroscopy was employed to study the effect that the synthesis conditions have on the structure and composition of amorphous carbon films.

FeCrAl alloys have been suggested as one of the most promising fuel cladding materials for the development of accident tolerance fuel. Creep is one of the important mechanical properties of the FeCrAl alloys used as fuel claddings under high temperature conditions. This work aims to elucidate the deformation feature and underlying mechanism during the creep process of nanocrystalline FeCrAl alloys using atomistic simulations. The creep curves at different conditions are simulated for FeCrAl alloys with grain sizes (GS) of 5.6–40 nm, and the dependence of creep on temperature, stress and GS are analyzed. The transitions of the mechanisms are analyzed by stress and GS exponents firstly, and further checked not only from microstructural evidence, but also from a vital comparison of activation energies for creep and diffusion. Under low stress conditions, grain boundary (GB) diffusion contributes more to the overall creep deformation than lattice diffusion does for the alloy with small GSs. However, for the alloy with larger GSs, lattice diffusion controls creep. Additionally, a high temperature helps the transition of diffusional creep from the GB to the dominant lattice. Under medium- and high-stress conditions, GB slip and dislocation motion begin to control the creep mechanism. The amount of GB slip increases with the temperature, or decreases with GS. GS and temperature also have an impact on the dislocation behavior. The higher the temperature or the smaller the GS is, the smaller the stress at which the dislocation motion begins to affect creep. [ABSTRACT FROM AUTHOR]

A photoluminescence (PL) and Raman spectroscopy study of various diamond samples that have high concentrations of nitrogen‐vacancy (NV) color centers up to multiple parts per million (ppm) is presented. With green, red, and near‐infrared (NIR) light excitation, it is demonstrated that while for samples with a low density of NV centers the signals are primarily dominated by Raman scattering from the diamond lattice, for higher density of NVs, a combination of Raman scattering from the diamond lattice and fluorescence from the NV centers is observed, while for the highest NV densities the Raman signals from diamond are completely overwhelmed by the intense NV's fluorescence. However, under NIR excitation, Raman diamond signatures can be observed for some diamonds. These observations reveal different roles of two mechanisms of light emission and contradict the naïve belief that Raman scattering enables the complete characterization of a diamond crystalline sample. [ABSTRACT FROM AUTHOR]

Nanocrystalline powders from the Permalloy family, Ni75Fe25, Ni79Fe16Mo5, and Ni77Fe14Cu5Mo4, were obtained by mechanical alloying starting from elemental powders. All compositions were milled for up to 24 h in a high-energy planetary ball mill. The powders were single phase and nanocrystalline as determined by X-ray diffraction studies, with larger flatted particle sizes for Ni75Fe25 (about 400 μm) and Ni77Fe14Cu5Mo4 (about 470 μm), and smaller particle sizes for Ni79Fe16Mo5 (about 170 μm). The homogeneity of the samples was verified by energy-dispersive X-ray spectroscopy (EDX). Soft magnetic composites were obtained by adding 3% of Araldite to the powders, followed by compaction at 700 MPa, and then polymerization. A very good powder covering by the polymer layer was proven by EDX elementals maps. The influence of composition change on the electrical resistivity of the compacts was studied. Hysteresis measurements in static and dynamic fields of up to 10 kHz were recorded, showing the influence of composition and particle size on the compact properties. [ABSTRACT FROM AUTHOR]

ZnSnN2 has potential applications in photocatalysis and photovoltaics. However, the difficulty in preparing nondegenerate ZnSnN2 hinders its device application. Here, the preparation of low-electron-density nanocrystalline ZnSnN2 and its device application are demonstrated. Nanocrystalline ZnSnN2 was prepared with reactive sputtering. Nanocrystalline ZnSnN2 with an electron density of approximately 1017 cm−3 can be obtained after annealing at 300 °C. Nanocrystalline ZnSnN2 is found to form Schottky contact with Ag. Both the current I vs. voltage V curves and the capacitance C vs. voltage V curves of these samples follow the related theories of crystalline semiconductors due to the limited long-range order provided by the crystallites with sizes of 2–10 nm. The I−V curves together with the nonlinear C−2−V curves imply that there are interface states at the Ag-nanocrystalline ZnSnN2 interface. The application of nanocrystalline ZnSnN2 to heterojunction solar cells is also demonstrated. [ABSTRACT FROM AUTHOR]

In this study, nanocrystalline Fe–Ni–Co ternary alloy powders with the composition of Fe50Ni50-xCox (x = 0–50) were prepared using a high-energy ball milling process after 30 h of milling time. Structure, microstructure, and magnetic properties were investigated in detail as a function of Co concentration using X-ray diffraction technique, scanning electron microscopy, vibrating sample magnetometer, and inductance/capacitance/resistance meter. The results indicate that BCC α-(Fe, Co) and FCC γ-(Fe, Ni) single-phase solid solutions with average crystallite sizes of 15 and 10 nm were formed successfully in Fe50Co50 and Fe50Ni50 alloys, respectively. In addition, there is a mixture of two solid solutions of FCC and BCC phases in the range of Fe–Ni–Co ternary alloy composition (i.e., 5 < × < 45). When Co concentration increases from x = 0 to x = 50, the saturation magnetization and relative permeability improve towards the Fe50Co50 alloy value, while the coercivity worsens from 12.6 to 63.4 Oe. [ABSTRACT FROM AUTHOR]

Recently, there has been an increasing demand for Co-based alloys in modern industrial applications because of their excellent magnetic properties. Therefore, given the importance of obtaining high-quality Co-based alloy, such as Co60Fe18Ti18Si4 (at%), was synthesized using the mechanical alloying (MA) process. The research concerned the microstructural, morphological, and magnetic properties evolution of Co60Fe18Ti18Si4 (at%) alloy powders synthesized by MA in a high-energy planetary ball mill under argon (Ar) atmosphere, at a speed of 300 rpm. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy, and vibrating sample magnetometer analysis were employed to characterize different alloy powdered samples as a function of MA time (10 min–50 h). The XRD result indicates that the synthesized Co-based alloy powder has a widened peak of bcc-(Co, Fe, Ti, Si) solid solution appeared after 50 h of milling time. The crystallite and the lattice strain were achieved to about 8 nm and 1.235%, respectively, after 50 h of milling time. The average particle size was obtained to about 2.727 µm after 50 h of milling time, as observed from SEM analysis. From the VSM analysis, it was observed that the synthesized alloy powders show soft ferromagnetic behaviour. After 50 h of milling time, the magnetic saturation and the coercivity were attained to about 89.68 emu/g and 155.08 Oe, respectively. [ABSTRACT FROM AUTHOR]

High-energy ball milling was used to produce two Fe-X-B (X = Nb, NiZr) nanocrystalline alloys. X-ray diffraction (XRD), differential scanning calorimetry (DSC), and vibrating sample magnetometry (VSM) were used to analyze the microstructure, thermal, and magnetic characteristics of the milled powders, the agglomerated particles (also generated during the milling process), and the compacted specimens of both alloys. The main crystallographic phase is always a bcc Fe-rich solid solution; whereas a minor Nb(B) phase is detected on powders and agglomerated particles in the Fe80Nb8B12 alloy. The crystalline size of the Fe80(NiZr)8B12 alloy is between 11 and 14 nm, whereas in the Fe80Nb8B12 alloy, it ranges between 8 and 12 nm. Microstrain and dislocation density are higher in agglomerated samples for both alloys than in milled powders. Thermal analysis detects structural relaxation and crystal growth exothermic processes with high dispersion in the temperature intervals and in the calculated apparent activation energy of the main crystallization process. Regarding magnetic behavior, the coercivity values of all powdered-agglomerated specimens were around 800 A/m. The coercivity is higher in compacted sample, but controlled annealing favors enhanced soft behavior. [ABSTRACT FROM AUTHOR]

The effect of Mg replacement with Al on the discharge capacity of Mg2Cu powder mixture was investigated. The mixture of nanocrystalline powder was prepared via mechanical alloying (MA) technique with a high energy planetary ball mill. In addition, different moles of Al (0.05, 0.1, 0.15, 0.2, and 0.3 M) were substituted to Mg2Cu powder. X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to analyze changes in structure, morphology, and grain size. The obtained powder was utilized as an anode in a nickel—metal hydride battery (Ni—MH). In the specimens with 0.05 M Al content, the orthorhombic structure of Mg2Cu is emerged after 5 h milling. The results reveal that more than 0.1 M Al substitution leads to an appearance of MgCu2 peaks. Al substitution does not affect microstructure uniformity; however, it causes a decrease in crystalline size and lattice parameters. The selected area diffraction (SAD) pattern elucidates that the electrode with the Mg1.9Al0.1Cu chemical composition and 20 h milling has the maximum discharge capacity. [ABSTRACT FROM AUTHOR]

This paper describes the synthesis of Ce-substituted Y-type barium hexaferrites (Co 2 –Y) {Ba 2 Co 2 Fe 12-x Ce x O 22 (0 ≤ x ≥ 0.30)} through the sol-gel auto-combustion route and its suitability as a heterogeneous catalyst for the reduction of nitroaromatic-compounds, one of the significant water contaminants. The synthesized nanocrystalline hexaferrite powders were characterized using XRD, FTIR, BET, SEM, and VSM. Furthermore, the catalytic functioning of the Co 2 –Y hexaferrite powder was evaluated based on the isolated yield of aniline in the reaction product through column chromatography. It was found that 100 mg pure Co 2 –Y hexaferrite samples could provide complete conversion of nitrobenzene and 65% selectivity of aniline within the water as a solvent and two mmol of reducing agent, hydrated hydrazine (N 2 H 2.H 2 O), at 100 °C for 12 h. The influence of Ce substitution at the iron site for the aniline selectivity was also investigated in optimized situations. In comparison with pure Co 2 –Y hexaferrite, the catalytic efficiency was considerably enriched in all substituted samples and obtained its extreme performance (73% selectivity of aniline) with Ba 2 Co 2 Fe 11.80 Ce 0.20 O 22 ferrite. The enriched performance was explained with the help of surface chemistry using the XPS & BET analysis for these samples. The as-prepared catalysts were magnetically-separable and recycled for five subsequent trials without any significant losses of catalytic performance. This catalyst may be convenient to be adopted for industrial applications due to its ease of synthesis, extraordinary stability, superior catalytic competence, and cost-effectiveness. [ABSTRACT FROM AUTHOR]

Nanocrystalline Ni–Mo and Ni–Mo–ZrO 2 coatings were designed and successfully fabricated via electrodeposition process in direct current mode. Impacts of molybdate and ZrO 2 nanoparticles, cathodic current density (i c) on surface, structure and performance of Ni–Mo alloy were analyzed. Electrochemical behaviors were evaluated by electrochemical impedance method in sodium chloride solution. A more compact and consistent surface morphology was prepared by introducing molybdate in nickel. Grain sizes of Ni–Mo alloy decreased as molybdate increased from 2 to 6 g L−1, and enlarged as i c increased. After incorporation of ZrO 2 , the grains initially decreased to 12 nm and later increased to 18 nm. The structure of the deposit is a face-centered cubic phase. With the increase of molybdate content, the preferential Ni (220) crystal plane was changed to oriented (111) plane. The Ni–Mo alloy comprises 91 wt% Ni and 5.4 wt% Mo. R a of Ni–Mo–ZrO 2 was 73 ± 4 nm. Ni–Mo alloys obtained at 20 mA cm−2 and 2 g L−1 molybdate possess the best corrosion-resistant behavior. Incorporation of ZrO 2 can strengthen electrochemical stability and anti-wear behavior of Ni–Mo alloy. The inclusion of ZrO 2 refined the grain size from 18 to 12 nm. The Ni–Mo/ZrO 2 coatings electrodeposited under 2–4 g L−1 Na 2 MoO 4 ·2H 2 O, 20–40 mA cm−2, 10–15 g L−1 ZrO 2 have excellent wear and corrosion resistance. [ABSTRACT FROM AUTHOR]

Surface modification improves the performance of materials in practical applications. In this paper, mechanical alloying pretreatment is adopted. Advanced non-equilibrium processing of a high-current pulse electron beam is then used to obtain an Sn-rich Ni-Sn alloy layer, characterized by a higher surface hardness than the initial pure nickel layer. In addition, the atomic structure of the Sn-doped nickel substrate in the alloy layer is simulated, and the improvement of the alloy layer is analyzed based on the first principle. Mechanical alloying and electron beam irradiation form fine and even nanocrystals on the surface of the nickel. Sn doping is also important for enlarging the lattice and increasing the stress. [ABSTRACT FROM AUTHOR]

PVA-capped nanocrystalline CdSe thin films are deposited on chemically clean glass substrates by chemical bath deposition technique using Cadmium acetate [Cd(CH3COO)2.3H2O and Sodium Selenosulfate (Na2SeSO3) as Cd2+ and Se2- ions sources respectively. Polyvinyl Alcohol (PVA) is act as a capping agent. Films of five different molarities (0.1 M-0.50M) of same pH value 8 were prepared at room temperature 298 K. The characteristics of the prepared CdSe thin films are investigated in detail by measuring their optical and electrical properties. The band gap energy of 2.16-2.49 eV was determined from the optical absorption spectra. The optical band gap decrease with increase in molarities. The electrical conductivity measured using two co-planar Aluminium electrodes are found to increase with increase in temperature showing semiconducting nature of the films. The electrical conductivity at room temperature is found to be of the order of 10-4 O-1 cm-1. [ABSTRACT FROM AUTHOR]

Burns and chronic wounds present significant challenges in wound management due to risks of infection, excessive inflammation, and prolonged healing. Silver-based treatments have long been central to burn care, but limitations have prompted the exploration of nanocrystalline silver as an alternative, with its nanoscale properties offering distinct benefits. This paper reviews the structure, properties, mechanisms of action, and clinical applications of nanocrystalline silver in burn and general wound management, with particular emphasis on how wound healing processes inform the application of these dressings. Nanocrystalline silver's high surface area-to-volume ratio and crystal structure enhance its antimicrobial and anti-inflammatory efficacy. Nanocrystalline silver's mechanisms of action are disrupting cellular functions, inducing DNA damage, and inhibiting biofilms. Clinical studies demonstrate accelerated healing and reduced inflammation compared to traditional treatments. Whilst nanocrystalline silver dressings are costly, their effectiveness in lowering drug-resistant infections and minimising complications supports a financial case for their use, potentially reducing overall wound care expenses. Considerations of cytotoxicity, allergic reactions, and accessibility underscore the importance of individualised treatment selection based on wound and patient factors. In conclusion, nanocrystalline silver holds substantial promise in burn wound management, and further research is warranted to optimise its therapeutic potential and economic benefits in clinical practice., (© 2024 The Author(s). Wound Repair and Regeneration published by Wiley Periodicals LLC on behalf of The Wound Healing Society.)

The SiC particle (SiCp) reinforced magnesium matrix composite powders (AZ91‒xSiCp, x=5%, 10%, 15%, volume fraction) were synthesized by mechanical milling. After the mechanical milling, the grain size of the magnesium matrix was refined to nanoscale, and the ultrafine SiC particles were dispersed into the magnesium matrix uniformly. The effect of SiCp on the microstructure of the milled nanocrystalline AZ91 magnesium alloys was analyzed. In the results, SiCp could accelerate the refining of magnesium matrix. Meanwhile, both the dissolving of Al element into the magnesium matrix and the refining of SiCp are inhibited due to the increasing of SiCp. The hardness of AZ91‒xSiCp composites (x=5%, 10%, 15%) is HV 166, HV 175, and HV 185, respectively. The contribution ratio of grain boundary strengthening, Orowan strengthening, solid solution strengthening, and load-bearing strengthening to the milled AZ91‒xSiCp composites is about 86.9%, 7.4%, 1.8% and 3.8%, respectively.

Nanoindentation creep behavior and underlying mechanisms of nanocrystalline (NC) Ni and NC Ni-20 wt% Fe (Ni-Fe) alloy were investigated at room temperature by a new testing method. The continuous creep strain rate versus creep stress data and hence the continuous apparent activation volume versus creep stress data in the entire holding stage on each single sample were achieved under a loading rate-controlled mode by a cooperative use of the continuous stiffness measurement (CSM) technique. Furthermore, the dependence of the apparent activation volume on the creep stress was interpreted by performing a theoretical analysis. Based on the above experimental and theoretical results and the high-resolution transmission electron microscope observation of the microstructures, the effects of the loading rate and stacking fault energy on the nanoindentation creep behavior of NC Ni and NC Ni-Fe alloy and the underlying mechanisms were analyzed. It was demonstrated that NC Ni-Fe alloy shows higher creep resistance in the transient regime, but lower creep resistance in the steady-state regime compared to NC Ni. The contact stiffness data obtained by the CSM technique in a strain rate-controlled mode can be used to determine the creep stress data from the creep displacement data obtained in a loading rate-controlled mode.

With the widespread use of magneto-sensitive elements, magnetic shields are an important part of electronic equipment, ultra-sensitive atomic sensors, and in basic physics experiments. Particularly in Spin-exchange relaxation-free (SERF) co-magnetometers, the magnetic shield is an important component for maintaining the SERF state. However, the inherent noise of magnetic shield materials is an important factor limiting the measurement sensitivity and accuracy of SERF co-magnetometers. In this paper, both amorphous and nanocrystalline materials were designed and applied as the innermost magnetic shield of an SERF co-magnetometer. Magnetic noise characteristics of different amorphous and nanocrystalline materials used as the internal magnetic shielding layer of the magnetic shielding system were analyzed. In addition, the effects on magnetic noise due to adding aluminum to amorphous and nanocrystalline materials were studied. The experimental results show that compared with an amorphous material, a nanocrystalline material as the inner magnetic shield layer can effectively reduce the magnetic noise and improve the sensitivity and precision of the rotation measurement. Nanocrystalline material is very promising for inner shield composition in SERF co-magnetometers. Furthermore, its ultra-thin structure and low cost have significant application value in the miniaturization of SERF co-magnetometers. [ABSTRACT FROM AUTHOR]

NANOMET-type soft magnetic alloys of Fe82Si4B10P3Cu1 and Fe78Si8B10P3Cu1 were studied. Nanocrystalline alloys were prepared by annealing the amorphous precursors at a temperature of 420 °C for 20 and 60 min in vacuum and in Ar atmosphere. The effect of the annealing atmosphere and time of annealing on the alloy structural and magnetic properties were investigated by X-ray diffraction (XRD), Mössbauer spectroscopy (MS), magnetic measurements and atomic force microscopy (AFM). XRD unveiled partial crystallization of the Fe82Si4B10P3Cu1 alloy and confirmed amorphous structure of the Fe78Si8B10P3Cu1 alloy. The technique also indicated larger grain size after annealing in vacuum as compared to that in argon. MS disclosed the effect of the silicon content on the annealed alloys microstructure, namely the lower relative volumetric fraction of the A8 crystalline phase component for the alloy with 8 at. % Si as compared to the alloy with 4 at. % Si. Variations of the parameters reflecting the magnetic microstructure were also observed and are discussed with relation to different annealing times and atmospheres. Magnetic measurements showed better soft magnetic properties for sample with 8 at. % Si whose coercivity was lower as well as the determined magnetization work. They also indicated lower coercivity for argon annealed samples and showed that longer annealing times are reflected in the increased resultant coercivity. For both studied compositions, the AFM measurements inspecting the morphology of the sample surfaces manifested the presence of lower protrusions on the surfaces of the vacuum annealed samples as compared to the argon annealed ones, where also larger agglomerates were disclosed. [ABSTRACT FROM AUTHOR]

Purpose: Nanocrystalline LaB6, NdB6, Nd-doped LaB6 and La-doped NdB6 have been studied using the density functional theory (DFT) to study their electronic, optical and mechanical characteristics. The purpose of this paper is to address this issue. Design/methodology/approach: Nanocrystalline LaB6, NdB6, Nd-doped LaB6 and La-doped NdB6 have been studied using the DFT to study their electronic, optical and mechanical characteristics. The calculated lattice constants of LaB6, NdB6, Nd-doped LaB6 and La-doped NdB6 were 4.157, 4.118, 4.267 and 4.449, respectively. The lattice constant of La7Nd1B6 was increased when Nd is doped into LaB6. B p comprised the uppermost valence bands (VBs), whereas B s comprised the lowermost conduction bands (CBs). The authors' results showed that La doping reduced the work function of NdB6 and increased its thermionic emission characteristics. Findings: The authors' results showed that La doping reduced the work function of NdB6 and increased its thermionic emission characteristics. Originality/value: The work function of LaB6 was 2.7 eV, which is higher than that of La1Nd7B6 (2.64 eV). [ABSTRACT FROM AUTHOR]

The magnetic coupling resonant wireless power transfer (MCR-WPT) system is considered to be the most promising wireless power transfer (WPT) method because of its considerable transmission power, high transmission efficiency, and acceptable transmission distance. For achieving magnetic concentration, magnetic cores made of magnetic materials are usually added to MCR-WPT systems to enhance the coupling performance. However, with the rapid progress of WPT technology, the traditional magnetic materials gradually become the bottleneck that restricts the system power density enhancement. In order to meet the electromagnetic characteristics requirements of WPT systems, high-performance Mn-Zn and Ni-Zn ferrites, amorphous, nanocrystalline, and metamaterials have been developed rapidly in recent years. This paper introduces an extensive review of the magnetic materials of WPT systems, concluding with the state-of-the-art WPT technology and the development and application of high-performance magnetic materials. In addition, this study offers an exclusive reference to researchers and engineers who are interested in learning about the technology and highlights critical issues to be addressed. Finally, the potential challenges and opportunities of WPT magnetic materials are presented, and the future development directions of the technology are foreseen and discussed. [ABSTRACT FROM AUTHOR]

In the current study, pure aluminum (Al) powders were cryomilled with and without 3 wt.% pure magnesium (Mg) dopant for varying durations followed by spark plasma sintering (SPS) of powders to prepare bulk components with superior mechanical properties. The crystallite sizes were determined for powders and the bulk components by analyzing the X-ray diffraction (XRD) spectrum. The calculations indicated a reduction in crystallite size with the increase in the cryomilling duration. The results also showed a more significant decrease in the crystallite sizes for Al-3Mg samples than that of pure Al. The changes in the surface morphology of powders were characterized using scanning electron microscopy (SEM). The elemental mapping analysis at nanoscale was carried out using Energy-dispersive X-ray spectroscopy (EDX) in Scanning transmission electron microscopy (STEM). The mechanical properties of the bulk components were assessed using a Vickers Microhardness tester. The test results demonstrated an improvement in the hardness of Mg-doped components. Higher hardness values were also reported with an increase in the cryomilling duration. This article discusses the mechanisms for the reduction in crystallite size for pure Al and Al-3Mg and its subsequent impact on improving mechanical properties. [ABSTRACT FROM AUTHOR]

Diamond is a material of choice for the fabrication of optical windows and for protective and anti-reflecting coatings for optical materials. For these kinds of applications, the diamond coating must have a high purity and a low surface roughness to guarantee a high transparency. It should also be synthesized at low surface temperature to allow the deposition on low melting-point substrates such as glasses. In this work, the ability of a Distributed Antenna Array (DAA) microwave system operating at low temperature and low pressure in H2/CH4/CO2 gas mixture to synthesize nanocrystalline diamond (NCD) films on borosilicate and soda-lime glass substrates is investigated aiming at optical applications. The influence of the substrate temperature and deposition time on the film microstructure and optical properties is examined. The best film properties are obtained for a substrate temperature below 300 °C. In these conditions, the growth rate is around 50 nm·h−1 and the films are homogeneous and formed of spherical aggregates composed of nanocrystalline diamond grains of 12 nm in size. The resulting surface roughness is then very low, typically below 10 nm, and the diamond fraction is higher than 80%. This leads to a high transmittance of the NCD/glass systems, above 75%, and to a low absorption coefficient of the NCD film below 103 cm−1 in the visible range. The resulting optical band gap is estimated at 3.55 eV. The wettability of the surface evolves from a hydrophilic regime on the bare glass substrates to a more hydrophobic regime after NCD deposition, as assessed by the increase of the measured contact angle from less than 55° to 76° after the deposition of 100 nm thick NCD film. This study emphasizes that such transparent diamond films deposited at low surface temperature on glass substrate using the DAA microwave technology can find applications for optical devices. [ABSTRACT FROM AUTHOR]

The effects of grain size (GS) and distance between twin boundaries (d) on the tensile properties of nanocrystalline (NC) face-centered cubic Cu50Ni50 alloy are studied using the molecular dynamics simulations. The common neighbour analysis, dislocation extraction algorithm, shear strain, and von Mises stress configurations together with the total dislocation length, stress–strain relation, and tensile strength diagrams are presented to investigate the mechanical characteristics of the NC Cu50Ni50 specimens. The results exhibits that the twin boundaries significantly restrict the formation and propagation of the stacking faults. The integral deformation occurs under a combination of displacement, breakage, and self-destruction of the twin boundary along with the contraction and expansion of the grains. The tensile strength increases as the GS and the d increase, which agrees with the inverse Hall-Petch relation. The tensile strength of the conventional NC is higher than that of the twinned NC for each pair of specimens with the same GS. [ABSTRACT FROM AUTHOR]