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12 pages, 4507 KiB

Open AccessArticle

Transmission and Reflection Spectra of a Bragg Microcavity Filled with a Periodic Graphene-Containing Structure

by Irina V. Fedorova, Svetlana V. Eliseeva and Dmitrij I. Sementsov

Appl. Sci. 2023, 13(13), 7559; https://doi.org/10.3390/app13137559 - 27 Jun 2023

Cited by 1 | Viewed by 1023

Abstract

The transmission and reflection spectra of a one-dimensional microresonator structure with dielectric Bragg mirrors, the working cavity of which is filled with several “dielectric-graphene” or “semiconductor-graphene” periods with controlled material parameters, were obtained using transfer matrices and numerical methods. Carrier drift in graphene [...] Read more.

The transmission and reflection spectra of a one-dimensional microresonator structure with dielectric Bragg mirrors, the working cavity of which is filled with several “dielectric-graphene” or “semiconductor-graphene” periods with controlled material parameters, were obtained using transfer matrices and numerical methods. Carrier drift in graphene monolayers is created to achieve amplification, which makes it possible to use the hydrodynamic approximation to represent graphene conductivity in the terahertz range. The transformation of spectra is achieved both by changing the energy state of the graphene monolayers and by changing the external magnetic field. It is shown that amplification is observed in the region where the real part of the conductivity is negative as the chemical potential (Fermi energy) increases, and the coefficients T and R become substantially greater than unity. The results of the work may be of interest to developers of graphene-based controlled photonic devices. Full article

(This article belongs to the Special Issue Novel Nanomaterials and Nanostructures)

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22 pages, 5762 KiB

Open AccessArticle

Noncovalent Adsorption of Single-Stranded and Double-Stranded DNA on the Surface of Gold Nanoparticles

by Ekaterina A. Gorbunova, Anna V. Epanchintseva, Dmitrii V. Pyshnyi and Inna A. Pyshnaya

Appl. Sci. 2023, 13(12), 7324; https://doi.org/10.3390/app13127324 - 20 Jun 2023

Cited by 2 | Viewed by 1532

Abstract

Understanding the patterns of noncovalent adsorption of double-stranded nucleic acids (dsDNA) on gold nanoparticles (GNPs) was the aim of this study. It was found that the high-affinity motifs in DNA can and do act as an “anchor” for the fixation of the whole [...] Read more.

Understanding the patterns of noncovalent adsorption of double-stranded nucleic acids (dsDNA) on gold nanoparticles (GNPs) was the aim of this study. It was found that the high-affinity motifs in DNA can and do act as an “anchor” for the fixation of the whole molecule on the GNP (up to 98 ± 2 single-stranded (ss)DNA molecules per particle with diameter of 13 ± 2 nm). At the same time, the involvement of an “anchor” in the intramolecular DNA interaction can negatively affect the efficiency of the formation of ss(ds)DNA–GNP structures. It has been shown that the interaction of GNP with DNA duplexes is accompanied by their dissociation and competitive adsorption of ssDNAs on GNP, wherein the crucial factor of DNA adsorption efficiency is the intrinsic affinity of ssDNA to GNP. We propose a detailed scheme for the interaction of dsDNA with GNPs, which should be taken into account in studies of this type. Researchers focused on this field should accept the complicated nature of such objects and take into account the many competing processes, including the processes of adsorption and desorption of DNA on gold as well as the formation of secondary structures by individual DNA strands. Full article

(This article belongs to the Special Issue Novel Nanomaterials and Nanostructures)

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19 pages, 651 KiB

Open AccessArticle

Mesoscopic Effects of Interfacial Thermal Conductance during Fast Pre-Melting and Melting of Metal Microparticles

by Alexander Minakov and Christoph Schick

Appl. Sci. 2023, 13(12), 7019; https://doi.org/10.3390/app13127019 - 11 Jun 2023

Viewed by 1223

Abstract

Interfacial thermal conductance (ITC) affects heat transfer in many physical phenomena and is an important parameter for various technologies. The article considers the influence of various mesoscopic effects on the ITC, such as the heat transfer through the gas gap, near-field radiative heat [...] Read more.

Interfacial thermal conductance (ITC) affects heat transfer in many physical phenomena and is an important parameter for various technologies. The article considers the influence of various mesoscopic effects on the ITC, such as the heat transfer through the gas gap, near-field radiative heat transfer, and changes in the wetting behavior during melting. Various contributions to the ITC of the liquid-solid interfaces in the processes of fast pre-melting and melting of metal microparticles are studied. The effective distance between materials in contact is a key parameter for determining ITC. This distance changes significantly during phase transformations of materials. An unusual gradual change in ITC recently observed during pre-melting below the melting point of some metals is discussed. The pre-melting process does not occur on the surface but is a volumetric change in the microstructure of the materials. This change in the microstructure during the pre-melting determines the magnitude of the dispersion forces, the effective distance, and the near-field thermal conductance. The knowledge gained can be useful for understanding and optimizing various technological processes, such as laser additive manufacturing. Full article

(This article belongs to the Special Issue Novel Nanomaterials and Nanostructures)

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ITC components <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>G</mi> </mrow> <mrow> <mi>n</mi> <mi>f</mi> </mrow> </msub> <mo>(</mo> <mi>d</mi> <mo>)</mo> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>G</mi> </mrow> <mrow> <mi>g</mi> </mrow> </msub> <mo>(</mo> <mi>d</mi> <mo>)</mo> </mrow> </semantics></math> vs. distance <math display="inline"><semantics> <mrow> <mi>d</mi> </mrow> </semantics></math> for flat surfaces in nitrogen gas at <math display="inline"><semantics> <mrow> <mi>σ</mi> <mo>=</mo> </mrow> </semantics></math> 0.6, <math display="inline"><semantics> <mrow> <mi>p</mi> <mo>=</mo> </mrow> </semantics></math> 105 Pa, and <math display="inline"><semantics> <mrow> <mi>T</mi> <mo>=</mo> </mrow> </semantics></math> 300 K (a), as well as <math display="inline"><semantics> <mrow> <mi>T</mi> <mo>=</mo> </mrow> </semantics></math> 900 K (b). The near-field component is estimated as <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>G</mi> </mrow> <mrow> <mi>n</mi> <mi>f</mi> </mrow> </msub> <mo>∈</mo> <mo>(</mo> <msubsup> <mrow> <mi>G</mi> </mrow> <mrow> <mi>n</mi> <mi>f</mi> </mrow> <mrow> <mi>m</mi> <mi>a</mi> <mi>x</mi> </mrow> </msubsup> <mo>/</mo> <mn>100</mn> <mo>,</mo> <mtext> </mtext> <msubsup> <mrow> <mi>G</mi> </mrow> <mrow> <mi>n</mi> <mi>f</mi> </mrow> <mrow> <mi>m</mi> <mi>a</mi> <mi>x</mi> </mrow> </msubsup> <mo>/</mo> <mn>10</mn> <mo>)</mo> </mrow> </semantics></math>. Full article ">

16 pages, 1531 KiB

Open AccessArticle

Steady-State Crack Growth in Nanostructured Quasi-Brittle Materials Governed by Second Gradient Elastodynamics

by Yury Solyaev

Appl. Sci. 2023, 13(10), 6333; https://doi.org/10.3390/app13106333 - 22 May 2023

Cited by 2 | Viewed by 1126

Abstract

The elastodynamic stress field near a crack tip propagating at a constant speed in isotropic quasi-brittle material was investigated, taking into account the strain gradient and inertia gradient effects. An asymptotic solution for a steady-state Mode-I crack was developed within the simplified strain [...] Read more.

The elastodynamic stress field near a crack tip propagating at a constant speed in isotropic quasi-brittle material was investigated, taking into account the strain gradient and inertia gradient effects. An asymptotic solution for a steady-state Mode-I crack was developed within the simplified strain gradient elasticity by using a representation of the general solution in terms of Lamé potentials in the moving framework. It was shown that the derived solution predicts the nonsingular stress state and smooth opening profile for the growing cracks that can be related to the presence of the fracture process zone in the micro-/nanostructured quasi-brittle materials. Note that similar asymptotic solutions have been derived previously only for Mode-III cracks (under antiplane shear loading). Thus, the aim of this study is to show the possibility of analytical assessments on the elastodynamic crack tip fields for in-plane loading within gradient theories. By using the derived solution, we also performed analysis of the angular distribution of stresses and tractions for the moderate speed of cracks. It was shown that the usage of the maximum principal stress criterion within second gradient elastodynamics allows us to describe a directional stability of Mode-I crack growth and an increase in the dynamic fracture toughness with the crack propagation speed that were observed in the experiments with quasi-brittle materials. Therefore, the possibility of the effective application of regularized solutions of strain gradient elasticity for the refined analysis of dynamic fracture processes in the quasi-brittle materials with phenomenological assessments on the cohesive zone effects is shown. Full article

(This article belongs to the Special Issue Novel Nanomaterials and Nanostructures)

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Illustration for the growing crack problem with global and local (moving) coordinate systems. Opening mode under remotely applied loading is considered. Solution is found in the vicinity of a crack tip, where <math display="inline"><semantics> <mrow> <mover accent="true"> <mi>r</mi> <mo>¯</mo> </mover> <mo>≪</mo> <mn>1</mn> </mrow> </semantics></math>, i.e., <math display="inline"><semantics> <mrow> <mi>r</mi> <mo>≪</mo> <mi>l</mi> </mrow> </semantics></math>. Full article ">Figure 2
Influence of Poisson’s ratio (a) and Mach number (b) of the deformations of small circles around the crack tip in SGET (left) and classical (right) asymptotic steady-state solutions. Full article ">Figure 3
Influence of dilatational (a) and rotational (b) amplitudes on the deformed state around the tip of crack. Full article ">Figure 4
Typical dependence of normalized tractions and double tractions on angular coordinate (a) and in-plane distribution of normalized hoop traction <math display="inline"><semantics> <msub> <mover accent="true"> <mi>t</mi> <mo>^</mo> </mover> <mi>θ</mi> </msub> </semantics></math> ((b), crack is shown by thick black line) in SGET asymptotic solution. Full article ">Figure 5
Angular distribution of normalized hoop traction (a) and radial traction (b) for different values of Mach number and Poisson’s ratio. Full article ">Figure 6
Angular distribution of normalized stress components <math display="inline"><semantics> <msub> <mover accent="true"> <mi>σ</mi> <mo>^</mo> </mover> <mrow> <mi>θ</mi> <mi>θ</mi> </mrow> </msub> </semantics></math> (a), <math display="inline"><semantics> <msub> <mover accent="true"> <mi>σ</mi> <mo>^</mo> </mover> <mrow> <mi>r</mi> <mi>θ</mi> </mrow> </msub> </semantics></math> (b), <math display="inline"><semantics> <msub> <mover accent="true"> <mi>σ</mi> <mo>^</mo> </mover> <mrow> <mi>r</mi> <mi>r</mi> </mrow> </msub> </semantics></math> (c) evaluated at different distances from the crack tip and for the values of Mach number <math display="inline"><semantics> <mrow> <msub> <mi>m</mi> <mn>2</mn> </msub> <mo>=</mo> <mn>0.2</mn> </mrow> </semantics></math> (solid lines) and <math display="inline"><semantics> <mrow> <msub> <mi>m</mi> <mn>2</mn> </msub> <mo>=</mo> <mn>0.01</mn> </mrow> </semantics></math> (dashed lines). Full article ">Figure 7
Angular distribution of normalized maximum principal stress (a) and maximum shear stress (b) and distribution of the normalized maximum principal stress along the crack propagation direction (along <math display="inline"><semantics> <msub> <mi>x</mi> <mn>1</mn> </msub> </semantics></math> at <math display="inline"><semantics> <mrow> <msub> <mi>x</mi> <mn>2</mn> </msub> <mo>=</mo> <mn>0</mn> </mrow> </semantics></math>) for different values of amplitude ratio <math display="inline"><semantics> <msub> <mi>k</mi> <mi>θ</mi> </msub> </semantics></math> (c). The values of Mach number are <math display="inline"><semantics> <mrow> <msub> <mi>m</mi> <mn>2</mn> </msub> <mo>=</mo> <mn>0.2</mn> </mrow> </semantics></math> (solid lines) and <math display="inline"><semantics> <mrow> <msub> <mi>m</mi> <mn>2</mn> </msub> <mo>=</mo> <mn>0.01</mn> </mrow> </semantics></math> (dashed lines). Full article ">

16 pages, 4310 KiB

Open AccessArticle

Magnetic and Optical Properties of Natural Diamonds with Subcritical Radiation Damage Induced by Fast Neutrons

by Nikolai A. Poklonski, Andrey A. Khomich, Ivan A. Svito, Sergey A. Vyrko, Olga N. Poklonskaya, Alexander I. Kovalev, Maria V. Kozlova, Roman A. Khmelnitskii and Alexander V. Khomich

Appl. Sci. 2023, 13(10), 6221; https://doi.org/10.3390/app13106221 - 19 May 2023

Cited by 2 | Viewed by 1691

Abstract

Raman spectroscopy and magnetic properties of the natural single crystalline diamonds irradiated with high fluences of fast reactor neutrons have been investigated. Raman spectra transformations were studied in the range from moderate levels up to radiation damage leading to diamond graphitization. The selection [...] Read more.

Raman spectroscopy and magnetic properties of the natural single crystalline diamonds irradiated with high fluences of fast reactor neutrons have been investigated. Raman spectra transformations were studied in the range from moderate levels up to radiation damage leading to diamond graphitization. The selection of fast neutrons irradiated diamonds for magnetic measurements was carried out according to Raman scattering data on the basis of the intensity criterion and the spectral position of the “1640” band. It was found that in natural diamonds irradiated with neutrons with an extremely high subcritical fluence F = 5 × 10²⁰ cm⁻², the transition from a diamagnetic to a ferromagnetic state is observed at the Curie–Weiss temperature of ≈150 K. The energy of the exchange magnetic interaction of uncompensated spins is estimated to be ≈1.7 meV. The differential magnetic susceptibility estimated from the measurements of magnetic moment for temperature 2 K in the limit of B ≈ 0 is χ_diff ≈ 1.8 × 10⁻³ SI units. The nature of magnetism in radiation-disordered single-crystal hydrogen- and metal-free natural diamond grains was discussed. Full article

(This article belongs to the Special Issue Novel Nanomaterials and Nanostructures)

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Raman spectra of natural and CVD diamonds unirradiated and irradiated with fast reactor neutrons with fluences F from 3 × 1018 to 5 × 1020 cm−2 (see also [<a href="#B49-applsci-13-06221" class="html-bibr">49</a>]) or uniformly implanted with multiple-energy keV helium ions with a total dose of 1 × 1017 and 2.5 × 1017 cm−2. All spectra were recorded with excitation at wavelength λ = 473 nm except for the spectra at F = 3 × 1018 cm−2, which was recorded with excitation at λ = 532 nm. Full article ">Figure 2
Position (left axis) of the “1640” band and ratio “1640”-to-boson peaks (right axis) in Raman spectra of natural diamonds irradiated with fast neutrons or He-implanted as functions of radiation damage. Dashed lines are guides to eyes. Yellow circles show the position of the “1640” band and ratio “1640”-to-boson peaks corresponding to the critical level of radiation damage of diamond. Full article ">Figure 3
Transformation of the Raman spectra of fast neutron-irradiated natural diamond crystal with fluence of 5 × 1020 cm−2 depending on the annealing temperature (1 h at each temperature in the range of 100–1300 °C = 373–1573 K). Spectra were recorded with excitation at λ = 473 nm. Full article ">Figure 4
Deconvolution of “1640” and second-order bands of the Raman spectra of fast neutron-irradiated (F = 5 × 1020 cm−2) natural diamond after its annealing at 800 °C (see <a href="#applsci-13-06221-f003" class="html-fig">Figure 3</a>). The contours of the Lorentzian form of the “1640” band of the first and second order are shown in color. Full article ">Figure 5
Magnetic moment M of natural diamond grains (113 pcs) irradiated with fast reactor neutrons (F = 5 × 1020 cm−2). The measurement absolute temperatures (T from 2 to 300 K) are shown in the figure. Full article ">Figure 6
Differential magnetic susceptibility χdiff(B) = (μ0/V)dM/dB (in SI units) of natural diamond grains (113 pcs, V ≈ 7.4 mm3) irradiated with fast neutrons (F = 5 × 1020 cm−2). The measurement absolute temperatures (T = 2 and 4 K) are shown in the figure. Full article ">

15 pages, 56529 KiB

Open AccessArticle

Synthesis and Printing Features of a Hierarchical Nanocomposite Based on Nickel–Cobalt LDH and Carbonate Hydroxide Hydrate as a Supercapacitor Electrode

by Tatiana L. Simonenko, Nikolay P. Simonenko, Philipp Yu. Gorobtsov, Andrey S. Nikitin, Aytan G. Muradova, Yuri M. Tokunov, Stanislav G. Kalinin, Elizaveta P. Simonenko and Nikolay T. Kuznetsov

Appl. Sci. 2023, 13(10), 5844; https://doi.org/10.3390/app13105844 - 9 May 2023

Cited by 4 | Viewed by 2149

Abstract

The hydrothermal synthesis of a hierarchically organized nanocomposite based on nickel–cobalt carbonate hydroxide hydrate of composition M(CO₃)_0.5(OH)·0.11H₂O (where M is Ni²⁺ and Co²⁺) and nickel–cobalt layered double hydroxides (NiCo-LDH) was studied. Using synchronous thermal [...] Read more.

The hydrothermal synthesis of a hierarchically organized nanocomposite based on nickel–cobalt carbonate hydroxide hydrate of composition M(CO₃)_0.5(OH)·0.11H₂O (where M is Ni²⁺ and Co²⁺) and nickel–cobalt layered double hydroxides (NiCo-LDH) was studied. Using synchronous thermal analysis (TGA/DSC), it was determined that the material retained thermal stability up to 200 °C. The crystal structure of the powder and the set of functional groups in its composition were determined by X-ray diffraction analysis (XRD) and Fourier transform infrared spectroscopy (FTIR). The resulting hierarchically organized nanopowder was employed as a functional ink component for microplotter printing of an electrode film, which is an array of miniature planar structures with a diameter of about 140 μm, on the surface of a nickel-plated steel substrate. Using scanning electron microscopy (SEM), it was established that the main area of the electrode “pixels” represents a thin film of individual nanorods with periodic inclusions of larger hierarchically organized spherical formations. According to atomic force microscopy (AFM) data, the mean square roughness of the material surface was 28 nm. The electrochemical properties of the printed composite film were examined; in particular, the areal specific capacitance at different current densities was calculated, and the electrochemical kinetics of the material was studied by impedance spectroscopy. It was found that the electrode material under study exhibited relatively low R_s and R_ct resistance, which indicates active ion transfer at the electrode/electrolyte interface. Full article

(This article belongs to the Special Issue Novel Nanomaterials and Nanostructures)

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15 pages, 7065 KiB

Open AccessArticle

Work Function, Sputtering Yield and Microhardness of an Al-Mg Metal-Matrix Nanostructured Composite Obtained with High-Pressure Torsion

by Rinat Kh. Khisamov, Ruslan U. Shayakhmetov, Yulay M. Yumaguzin, Andrey A. Kistanov, Galiia F. Korznikova, Elena A. Korznikova, Konstantin S. Nazarov, Gulnara R. Khalikova, Rasim R. Timiryaev and Radik R. Mulyukov

Appl. Sci. 2023, 13(8), 5007; https://doi.org/10.3390/app13085007 - 16 Apr 2023

Cited by 4 | Viewed by 1865

Abstract

Severe plastic deformation has proven to be a promising method for the in situ manufacturing of metal-matrix composites with improved properties. Recent investigations have revealed a severe mixing of elements, as well as the formation of non-equilibrium intermetallic phases, which are known to [...] Read more.

Severe plastic deformation has proven to be a promising method for the in situ manufacturing of metal-matrix composites with improved properties. Recent investigations have revealed a severe mixing of elements, as well as the formation of non-equilibrium intermetallic phases, which are known to affect physical and mechanical properties. In this work, a multilayered aluminum–magnesium (Al-Mg) nanostructured composite was fabricated using constrained high-pressure torsion (HPT) in a Bridgeman-anvil-type unit. A microstructure investigation and X-ray diffraction analysis allowed us to identify the presence of intermetallic Al₃Mg₂ and Al₁₂Mg₁₇ phases in the deformed nanostructured composite. The sputtering yield of the Al₃Mg₂ and Al₁₂Mg₁₇ phases was found to be 2.2 atom/ion and 1.9 at/ion, respectively, which is lower than that of Mg (2.6 at/ion). According to density functional theory (DFT)-based calculations, this is due to the higher surface-binding energy of the intermetallic phases (3.90–4.02 eV with the Al atom removed and 1.53–1.71 eV with the Mg atom removed) compared with pure Al (3.40–3.84 eV) and Mg (1.56–1.57 eV). In addition, DFT calculations were utilized to calculate the work functions (WFs) of pure Al and Mg and the intermetallic Al₃Mg₂ and Al₁₂Mg₁₇ phases. The WF of the obtained Al-Mg nanostructured composite was found to be 4 eV, which is between the WF value of Al (4.3 eV) and Mg (3.6 eV). The WF of the Al12Mg17 phase was found to be in a range of 3.63–3.75 eV. These results are in close agreement with the experimentally measured WF of the metal matrix composite (MMC). Therefore, an intermetallic alloy based on Al₁₂Mg₁₇ is proposed as a promising cathode material for various gas-discharge devices, while an intermetallic alloy based on Al₃Mg₂ is suggested as a promising optical- and acoustic-absorbing material. Full article

(This article belongs to the Special Issue Novel Nanomaterials and Nanostructures)

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XRD patterns of Al (a), Mg (b) and Al-Mg nanostructured composites under HPT conditions (c) and after further annealing at 275 °C (d). Full article ">Figure 2
SEM images (BSE mode) of the Al-Mg nanostructured composite cross-section at different magnifications and element distribution along the line shown at the top of the panel in the form of a relative intensity plot in relation to the scanning distance of the Mg and Al, marked by green and red, respectively. Full article ">Figure 3
SEM image (SE mode) of the surface of the Al-Mg nanostructured composite after HPT and annealing following ion irradiation. Full article ">Figure 4
SEM images (SE mode) of the Al-Mg nanostructured composite surface after ion irradiation. Tilt angle is 45°. Full article ">Figure 5
SEM image combined with an elemental map of the Al (in red) and Mg (in green). The element composition is shown along lines 1–5 at the top of the panel in the form of a relative intensity plot in relation to the scanning distance of the Al and Mg, marked in red and blue, respectively. Full article ">Figure 6
AFM image (a) and profile (b) of the Al-Mg composite surface after irradiation. Full article ">Figure 7
Optical image of the Al-Mg nanostructured composite surface before (a) and after (b) ion irradiation. Full article ">

14 pages, 2476 KiB

Open AccessArticle

Rapid Synthesis of Silver Nanowires in the Polyol Process with Conventional and Microwave Heating

by Grzegorz Dzido, Aleksandra Smolska and Muhammad Omer Farooq

Appl. Sci. 2023, 13(8), 4963; https://doi.org/10.3390/app13084963 - 14 Apr 2023

Cited by 4 | Viewed by 3590

Abstract

Silver nanowires (AgNWs) represent an excellent material for many advanced applications due to their thermal and electrical properties. However, synthesising materials with the desired characteristics requires knowledge of the parameters affecting their size and an appropriate fabrication method. This paper presents a study [...] Read more.

Silver nanowires (AgNWs) represent an excellent material for many advanced applications due to their thermal and electrical properties. However, synthesising materials with the desired characteristics requires knowledge of the parameters affecting their size and an appropriate fabrication method. This paper presents a study on the synthesis of silver nanowires using the polyol process by conventional and microwave heating. Various polyols (1,2-ethanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol) with different viscosities and dielectric properties were used as reductants. It resulted in nanowires with an average diameter of 119–198 nm. It was found that, in contrast to the viscosity and dielectric constant of the alcohol used, the heating method had a limited effect on the average diameter and length value of the final product. The performed studies indicate an optimal strategy for fabricating one-dimensional silver nanostructures using the polyol method. Full article

(This article belongs to the Special Issue Novel Nanomaterials and Nanostructures)

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19 pages, 5446 KiB

Open AccessArticle

Combined Steam and CO₂ Reforming of Methane over Ni-Based CeO₂-MgO Catalysts: Impacts of Preparation Mode and Pd Addition

by Lyudmila Okhlopkova, Igor Prosvirin, Mikhail Kerzhentsev and Zinfer Ismagilov

Appl. Sci. 2023, 13(8), 4689; https://doi.org/10.3390/app13084689 - 7 Apr 2023

Cited by 2 | Viewed by 1595

Abstract

The sol–gel template technique makes it possible to synthesize a stable and efficient nickel catalyst based on magnesium-modified cerium oxide Ce_0.5Mg_0.5O_1.5 for the combined steam and CO₂ reforming of methane. To stabilize dispersed forms of the active [...] Read more.

The sol–gel template technique makes it possible to synthesize a stable and efficient nickel catalyst based on magnesium-modified cerium oxide Ce_0.5Mg_0.5O_1.5 for the combined steam and CO₂ reforming of methane. To stabilize dispersed forms of the active component in the matrix of the support, the catalysts were synthesized by changing the support precursor (cerium acetate and chloride), the active component composition (Ni, NiPd) and the method of introducing nanoparticles. The relationship was established between the physicochemical and catalytic characteristics of the samples. The use of cerium acetate as a support precursor provided smaller pore and crystallite sizes of the support, a stabilization of the dispersed forms of the active component, and excellent catalytic characteristics. The introduction of Pd into the Ni nanoparticles (Pd/Ni = 0.03) increased the resistance of the active component to sintering during the reaction, ensuring stable operation for 25 h of operation. The increased stability was due to a higher concentration of defective oxygen, a higher dispersion of bimetallic NiPd nanoparticles, and the Ni clusters strongly interacting with the NiO-MgO solid solution. An efficient and stable Ni_0.194Pd_0.006Ce_0.4Mg_0.4O_1.4 catalyst for the conversion of CO₂ into important chemicals was developed. With the optimal composition and synthesis conditions of the catalyst, the yield of the target products was more than 75%. Full article

(This article belongs to the Special Issue Novel Nanomaterials and Nanostructures)

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16 pages, 5612 KiB

Open AccessArticle

Gelation in Alginate-Based Magnetic Suspensions Favored by Poor Interaction among Sodium Alginate and Embedded Particles

by Alexander P. Safronov, Elena V. Rusinova, Tatiana V. Terziyan, Yulia S. Zemova, Nadezhda M. Kurilova, Igor. V. Beketov and Andrey Yu. Zubarev

Appl. Sci. 2023, 13(7), 4619; https://doi.org/10.3390/app13074619 - 6 Apr 2023

Cited by 3 | Viewed by 1649

Abstract

Alginate gels are extensively tested in biomedical applications for tissue regeneration and engineering. In this regard, the modification of alginate gels and solutions with dispersed magnetic particles gives extra options to control the rheo-elastic properties both for the fluidic and gel forms of [...] Read more.

Alginate gels are extensively tested in biomedical applications for tissue regeneration and engineering. In this regard, the modification of alginate gels and solutions with dispersed magnetic particles gives extra options to control the rheo-elastic properties both for the fluidic and gel forms of alginate. Rheological properties of magnetic suspensions based on Na-alginate water solution with embedded magnetic particles were studied with respect to the interfacial adhesion of alginate polymer to the surface of particles. Particles of magnetite (Fe₃O₄), metallic iron (Fe), metallic nickel (Ni), and metallic nickel with a deposited carbon layer (Ni@C) were taken into consideration. Storage modulus, loss modulus, and the shift angle between the stress and the strain were characterized by the dynamic mechanical analysis in the oscillatory mode. The intensity of molecular interactions between alginate and the surface of the particles was characterized by the enthalpy of adhesion which was determined from calorimetric measurements using a thermodynamic cycle. Strong interaction at the surface of the particles resulted in the dominance of the “fluidic” rheological properties: the prevalence of the loss modulus over the storage modulus and the high value of the shift angle. Meanwhile, poor interaction of alginate polymer with the surface of the embedded particles favored the “elastic” gel-like properties with the dominance of the storage modulus over the loss modulus and low values of the shift angle. Full article

(This article belongs to the Special Issue Novel Nanomaterials and Nanostructures)

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12 pages, 35888 KiB

Open AccessArticle

Effect of Segregation on Deformation Behaviour of Nanoscale CoCrCuFeNi High-Entropy Alloy

by Arseny M. Kazakov, Azat V. Yakhin, Elvir Z. Karimov, Rita I. Babicheva, Andrey A. Kistanov and Elena A. Korznikova

Appl. Sci. 2023, 13(6), 4013; https://doi.org/10.3390/app13064013 - 21 Mar 2023

Cited by 5 | Viewed by 1842

Abstract

A molecular dynamics (MD) simulation method is used to investigate the effect of grain boundary (GB) segregation on the deformation behavior of bicrystals of equiatomic nanoscale CoCrCuFeNi high-entropy alloy (HEA). The deformation mechanisms during shear and tensile deformation at 300 K and 100 [...] Read more.

A molecular dynamics (MD) simulation method is used to investigate the effect of grain boundary (GB) segregation on the deformation behavior of bicrystals of equiatomic nanoscale CoCrCuFeNi high-entropy alloy (HEA). The deformation mechanisms during shear and tensile deformation at 300 K and 100 K are analyzed. It is revealed that upon tensile deformation, the stacking fault formation, and twinning are the main deformation mechanisms, while for the shear deformation, the main contribution to the plastic flow is realized through the GB migration. The presence of the segregation at GBs leads to the stabilization of GBs, while during the shear deformation of the nanoscale CoCrCuFeNi HEA without the segregation at GBs, GBs are subject to migration. It is found that the GB segregation can differently influence the plasticity of the nanoscale CoCrCuFeNi HEA, depending on the elemental composition of the segregation layer. In the case of copper and nickel segregations, an increase in the segregation layer size enhances the plasticity of the nanoscale CoCrCuFeNi HEA. However, an increase in the thickness of chromium segregations deteriorates the plasticity while enhancing maximum shear stress. The results obtained in this study shed light on the development of HEAs with enhanced mechanical properties via GB engineering. Full article

(This article belongs to the Special Issue Novel Nanomaterials and Nanostructures)

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(a) The computational cell used for the simulations. (b) The bicrystal with the GB segregation of copper (colored in purple) and a crack in the middle of the GB. Full article ">Figure 2
(a) The shear stress–strain curves for the considered bicrystals. The corresponding type of segregated element is indicated in the legend for each bicrystal, while the case without GB segregation is denoted as Bicrystal. (b) Structure of the bicrystal with GB segregation of Cr at 12% shear deformation. Full article ">Figure 3
The shear stress–strain curves for the bicrystals with Cr segregation at GB. The corresponding thickness of the segregated layer (1, 3 or 5 Å) is indicated in the legend. The considered temperature is 300 K. Full article ">Figure 4
The tensile stress–strain curves for the considered bicrystals. The corresponding type of segregated element is indicated in the legend for each bicrystal, while the case without GB segregation is labeled as Bicrystal. The stress drop to zero corresponds to a break in the bicrystal. The considered temperature is 300 K. Full article ">Figure 5
Bicrystal with chromium segregation at 12% strain. Twins are shown in red. Atoms of the disordered structure are shown in grey. Full article ">Figure 6
The tensile stress–strain curves for the considered bicrystals. The corresponding type of segregated element is indicated in the legend for each bicrystal, while the case without GB segregation is denoted as Bicrystal. The stress drop to zero corresponds to a break in the bicrystal. The considered temperature is 300 K. Full article ">Figure 7
Bicrystals during stretching before breaking. Twins are shown in red, and atoms of the disordered structure are shown in grey. The figure shows the bicrystal with cobalt segregation (a), chromium segregation (b), copper segregation (c), iron segregation (d), and nickel segregation (e), and bicrystal without segregations (f). Full article ">Figure 8
The tensile stress–strain curves for the considered bicrystals. The corresponding type of segregated element is indicated in the legend for each bicrystal, while the case without GB segregation is denoted as Bicrystal. The stress drop to zero corresponds to a break in the bicrystal. The considered temperature is 100 K. The thickness of the segregated layer is 5 Å. Full article ">

14 pages, 508 KiB

Open AccessFeature PaperArticle

Characteristics of Resonant Tunneling in Nanostructures with Spacer Layers

by Konstantin Grishakov, Konstantin Katin and Mikhail Maslov

Appl. Sci. 2023, 13(5), 3007; https://doi.org/10.3390/app13053007 - 26 Feb 2023

Cited by 4 | Viewed by 1717

Abstract

The effect of spacer layers on electron transport through two-barrier nanostructures was studied using the numerical solution of the time-dependent Schrodinger–Poisson equations with exact discrete open boundary conditions. The formulation of the problem took into account both the active region consisting of a [...] Read more.

The effect of spacer layers on electron transport through two-barrier nanostructures was studied using the numerical solution of the time-dependent Schrodinger–Poisson equations with exact discrete open boundary conditions. The formulation of the problem took into account both the active region consisting of a quantum well and barriers, as well as the presence of highly doped contact layers and spacer layers. The use of the time formulation of the problem avoids the divergence of the numerical solution, which is usually observed when solving a stationary system of the Schrodinger–Poisson equations at small sizes of spacer layers. It is shown that an increase in the thickness of the emitter spacer leads to a decrease in the peak current through the resonant tunneling nanostructures. This is due to the charge accumulation effects, which, in particular, lead to a change in the potential in an additional quantum well formed in the emitter spacer region when a constant electric field is applied. The valley current also decreases as the thickness of the emitter spacer increases. The peak current and valley current are weakly dependent on the thickness of the collector spacer. The collector spacer thickness has a strong effect on the applied peak and valley voltages. The above features are valid for all three different resonant tunneling nanostructures considered in this study. For the RTD structures based on Al_0.3Ga_0.7As/GaAs, the optimized peak current value Ip_max = 5.6 × 10⁹ A/m² and the corresponding applied voltage V_p = 0.44 V. For the RTD structures based on AlAs/In_0.8Ga_0.2As, Ip_max = 14.5 × 10⁹ A/m² (V_p = 0.54 V); for RTD structures based on AlAs/In_0.53Ga_0.47As, Ip_max = 45.5 × 10⁹ A/m² (V_p = 1.75 V). Full article

(This article belongs to the Special Issue Novel Nanomaterials and Nanostructures)

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9 pages, 3057 KiB

Open AccessFeature PaperArticle

Nonlinear Transport and Magnetic/Magneto-Optical Properties of Co_x(MgF₂)_100-x Nanostructures

by Sergey A. Ivkov, Konstantin A. Barkov, Evelina P. Domashevskaya, Elena A. Ganshina, Dmitry L. Goloshchapov, Stanislav V. Ryabtsev, Alexander V. Sitnikov and Pavel V. Seredin

Appl. Sci. 2023, 13(5), 2992; https://doi.org/10.3390/app13052992 - 26 Feb 2023

Cited by 3 | Viewed by 1238

Abstract

The aim of this work was to comprehensively study the effect of the variable atomic composition and structural-phase state of Co_x(MgF₂)_100-x nanocomposites on their nonlinear transport and magnetic/magneto-optical properties. Micrometer-thick nanocomposite layers on glass substrates were obtained by [...] Read more.

The aim of this work was to comprehensively study the effect of the variable atomic composition and structural-phase state of Co_x(MgF₂)_100-x nanocomposites on their nonlinear transport and magnetic/magneto-optical properties. Micrometer-thick nanocomposite layers on glass substrates were obtained by means of ion-beam sputtering of a composite target in the argon atmosphere in a wide range of compositions (x = 16–59 at.%). Using a low metal content in the nanocomposite, magnesium fluoride was kept in the nanocrystalline state. As the metal content increased, nanocrystalline cobalt was formed. The value of the resistive percolation threshold, x_per = 37 at.%, determined from the concentration dependences of the electrical resistance of the nanocomposites coincided with the beginning of nucleation of the metallic nanocrystals in the MgF₂ dielectric matrix. The absolute value of the maximum negative magnetoresistive effect in the nanocomposites was 5% in a magnetic field of 5.5 kG at a Co concentration of x = 27 at.%. Full article

(This article belongs to the Special Issue Novel Nanomaterials and Nanostructures)

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XRD patterns of Cox(MgF2)100–x nanocomposites of various compositions on glass substrates [<a href="#B25-applsci-13-02992" class="html-bibr">25</a>]. Full article ">Figure 2
Concentration dependences of electrical resistance (a) and magnetoresistance (b) of Cox(MgF2)100-x nanocomposites. Full article ">Figure 3
Impedance diagrams (hodographs) for nanocomposites Cox(MgF2)100-x of different compositions (32 ≤ x ≤ 59). Full article ">Figure 4
Concentration dependencies of the transversal Kerr effect (TKE) for nanocomposites Cox(MgF2)100-x at different values of incident light energy. Full article ">Figure 5
The M–H loop for NC Co32(MgF2)68 and for NC Co27(MgF2)73, where the solid delta shows the M–H loop with an out-of-plane magnetic field, and the open delta presents the in-plane M–H loop. Full article ">Figure 6
Concentration dependence of the coercive force (Hc) for Cox(MgF2)100-x nanocomposites. Full article ">

7 pages, 1637 KiB

Open AccessCommunication

First Theoretical Realization of a Stable Two-Dimensional Boron Fullerene Network

by Bohayra Mortazavi

Appl. Sci. 2023, 13(3), 1672; https://doi.org/10.3390/app13031672 - 28 Jan 2023

Cited by 2 | Viewed by 1982

Abstract

Successful experimental realizations of two-dimensional (2D) C₆₀ fullerene networks have been among the most exciting latest advances in the rapidly growing field of 2D materials. In this short communication, on the basis of the experimentally synthesized full boron B₄₀ fullerene lattice, [...] Read more.

Successful experimental realizations of two-dimensional (2D) C₆₀ fullerene networks have been among the most exciting latest advances in the rapidly growing field of 2D materials. In this short communication, on the basis of the experimentally synthesized full boron B₄₀ fullerene lattice, and by structural minimizations of extensive atomic configurations via density functional theory calculations, we could, for the first time, predict a stable B₄₀ fullerene 2D network, which shows an isotropic structure. Acquired results confirm that the herein predicted B₄₀ fullerene network is energetically and dynamically stable and also exhibits an appealing thermal stability. The elastic modulus and tensile strength are estimated to be 125 and 7.8 N/m, respectively, revealing strong bonding interactions in the predicted nanoporous nanosheet. Electronic structure calculations reveal metallic character and the possibility of a narrow and direct band gap opening by applying the uniaxial loading. This study introduces the first boron fullerene 2D nanoporous network with an isotropic lattice, remarkable stability, and a bright prospect for the experimental realization. Full article

(This article belongs to the Special Issue Novel Nanomaterials and Nanostructures)

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13 pages, 33471 KiB

Open AccessArticle

Effect of Interatomic Potential on Simulation of Fracture Behavior of Cu/Graphene Composite: A Molecular Dynamics Study

by Liliya R. Safina, Elizaveta A. Rozhnova, Ramil T. Murzaev and Julia A. Baimova

Appl. Sci. 2023, 13(2), 916; https://doi.org/10.3390/app13020916 - 9 Jan 2023

Cited by 11 | Viewed by 2266

Abstract

Interatomic interaction potentials are compared using a molecular dynamics modeling method to choose the simplest, but most effective, model to describe the interaction of copper nanoparticles and graphene flakes. Three potentials are considered: (1) the bond-order potential; (2) a hybrid embedded-atom-method and Morse [...] Read more.

Interatomic interaction potentials are compared using a molecular dynamics modeling method to choose the simplest, but most effective, model to describe the interaction of copper nanoparticles and graphene flakes. Three potentials are considered: (1) the bond-order potential; (2) a hybrid embedded-atom-method and Morse potential; and (3) the Morse potential. The interaction is investigated for crumpled graphene filled with copper nanoparticles to determine the possibility of obtaining a composite and the mechanical properties of this material. It is observed that not all potentials can be applied to describe the graphene–copper interaction in such a system. The bond-order potential potential takes into account various characteristics of the bond (for example, the angle of rotation and bond lengths); its application increases the simulation time and results in a strong interconnection between a metal nanoparticle and a graphene flake. The hybrid embedded-atom-method/Morse potential and the Morse potential show different results and lower bonding between graphene and copper. All the potentials enable a composite structure to be obtained; however, the resulting mechanical properties, such as strength, are different. Full article

(This article belongs to the Special Issue Novel Nanomaterials and Nanostructures)

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8 pages, 1206 KiB

Open AccessCommunication

First-Principles Prediction of Structure and Properties of the Cu₂TeO₆ Monolayer

by Elena A. Korznikova, Vladimir A. Bryzgalov and Andrey A. Kistanov

Appl. Sci. 2023, 13(2), 815; https://doi.org/10.3390/app13020815 - 6 Jan 2023

Cited by 1 | Viewed by 1857

Abstract

In this work, first-principles calculations have been utilized to predict the existence of a new Cu₂TeO₆ monolayer. It is shown that the predicted material is dynamically and thermally stable. The Cu₂TeO₆ monolayer is also found to be [...] Read more.

In this work, first-principles calculations have been utilized to predict the existence of a new Cu₂TeO₆ monolayer. It is shown that the predicted material is dynamically and thermally stable. The Cu₂TeO₆ monolayer is also found to be a narrow band gap semiconductor with a band gap size of 0.20 eV. Considering the obtained properties of the Cu₂TeO₆ monolayer, it is proposed for applications in various nanodevices in electronics and straintronics. Full article

(This article belongs to the Special Issue Novel Nanomaterials and Nanostructures)

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Review

Jump to: Research

23 pages, 2912 KiB

Open AccessReview

Prospects for Combined Applications of Nanostructured Catalysts and Biocatalysts for Elimination of Hydrocarbon Pollutants

by Olga Maslova, Olga Senko, Marina A. Gladchenko, Sergey N. Gaydamaka and Elena Efremenko

Appl. Sci. 2023, 13(9), 5815; https://doi.org/10.3390/app13095815 - 8 May 2023

Cited by 4 | Viewed by 2049

Abstract

Due to the presence of environmental problems, it is urgent to improve the processes aimed at the processing and purification of hydrocarbon-containing wastes and wastewaters. The review presents the latest achievements in the development of nanostructured catalysts made from different materials that can [...] Read more.

Due to the presence of environmental problems, it is urgent to improve the processes aimed at the processing and purification of hydrocarbon-containing wastes and wastewaters. The review presents the latest achievements in the development of nanostructured catalysts made from different materials that can be used to purify oil-polluted wastewaters (petroleum refinery wastewater, oilfield-produced water, sulfur-containing extracts from pre-oxidized crude oil and oil fractions, etc.) and eliminate components of hydrocarbon pollutants (polyaromatic hydrocarbons, phenols, etc.). The results of the analysis of possible combinations of chemical and biological catalysts for deeper and more effective solutions to the problems are discussed. The possibilities of highly efficient elimination of hydrocarbon pollutants as a result of the hybrid application of nanoparticles (graphene oxide, mesoporous silica, magnetic nanocatalysts, etc.) or catalytic nanocomposites for advanced oxidation processes and biocatalysts (enzymes, cells of bacteria, mycelial fungi, phototrophic microorganisms and natural or artificial microbial consortia) are analyzed. Full article

(This article belongs to the Special Issue Novel Nanomaterials and Nanostructures)

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34 pages, 9921 KiB

Open AccessReview

Recent Trends in the Characterization and Application Progress of Nano-Modified Coatings in Corrosion Mitigation of Metals and Alloys

by Abhinay Thakur, Savaş Kaya and Ashish Kumar

Appl. Sci. 2023, 13(2), 730; https://doi.org/10.3390/app13020730 - 4 Jan 2023

Cited by 62 | Viewed by 4116

Abstract

Nanotechnology is a discipline of science and engineering that emphasizes developing, modifying, characterizing, and using nanoscale components in a variety of applications. Owing to their multiple advantages, including adhesion strength, surface hardness, long-term and extra-high-temperature corrosion resistance, improvement of interfacial behavior, etc., nanocoatings [...] Read more.

Nanotechnology is a discipline of science and engineering that emphasizes developing, modifying, characterizing, and using nanoscale components in a variety of applications. Owing to their multiple advantages, including adhesion strength, surface hardness, long-term and extra-high-temperature corrosion resistance, improvement of interfacial behavior, etc., nanocoatings are efficiently utilized to minimize the influence of a corrosive environment. Additionally, nanocoatings are often applied in thinner and finer concentrations, allowing for greater versatility in instrumentation and reduced operating and maintenance costs. The exemplary physical coverage of the coated substrate is facilitated by the fine dimensions of nanomaterials and the significant density of their grounded boundaries. For instance, fabricated self-healing eco-sustainable corrosion inhibitors including PAC/CuONPs, PAC/Fe₃O₄NPs, and PAC/NiONPs, with uniform distributions and particulate sizes of 23, 10, and 43 nm, correspondingly, were effective in producing PAC/MONPs nanocomposites which exhibited IE% of 93.2, 88.1, 96.1, and 98.6% for carbon steel corrosion in 1M HCl at the optimum concentration of 250 ppm. Therefore, in this review, further steps are taken into the exploration of the significant corrosion-mitigation potential and applications of nanomaterial-based corrosion inhibitors and nano-modified coatings, including self-healing nanocoatings, natural source-based nanocoatings, metal/metallic ion-based nanocoatings, and carbon allotrope-based nanocoatings, to generate defensive film and protection against corrosion for several metals and alloys. These have been illuminated through the in-depth discussion on characterization techniques such as scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), atomic force microscopy (AFM), energy dispersive spectroscopy (EDS), etc. After providing a general summary of the various types of nanomaterials and their protective mechanisms in wide corrosive media, we subsequently present a viewpoint on challenges and future directions. Full article

(This article belongs to the Special Issue Novel Nanomaterials and Nanostructures)

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