Nanomaterials

13 pages, 19717 KiB

Open AccessEditor’s ChoiceArticle

Area-Scalable 10⁹-Cycle-High-Endurance FeFET of Strontium Bismuth Tantalate Using a Dummy-Gate Process

by Mitsue Takahashi and Shigeki Sakai

Nanomaterials 2021, 11(1), 101; https://doi.org/10.3390/nano11010101 - 4 Jan 2021

Cited by 10 | Viewed by 6536

Strontium bismuth tantalate (SBT) ferroelectric-gate field-effect transistors (FeFETs) with channel lengths of 85 nm were fabricated by a replacement-gate process. They had metal/ferroelectric/insulator/semiconductor stacked-gate structures of Ir/SBT/HfO₂/Si. In the fabrication process, we prepared dummy-gate transistor patterns and then replaced the dummy [...] Read more.

Strontium bismuth tantalate (SBT) ferroelectric-gate field-effect transistors (FeFETs) with channel lengths of 85 nm were fabricated by a replacement-gate process. They had metal/ferroelectric/insulator/semiconductor stacked-gate structures of Ir/SBT/HfO₂/Si. In the fabrication process, we prepared dummy-gate transistor patterns and then replaced the dummy substances with an SBT precursor. After forming Ir gate electrodes on the SBT, the whole gate stacks were annealed for SBT crystallization. Nonvolatility was confirmed by long stable data retention measured for 10⁵ s. High erase-and-program endurance of the FeFETs was demonstrated for up to 10⁹ cycles. By the new process proposed in this work, SBT-FeFETs acquire good channel-area scalability in geometry along with lithography ability. Full article

(This article belongs to the Special Issue Electronic Nanodevices)

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8 pages, 5399 KiB

Open AccessEditor’s ChoiceArticle

Thermodynamics of the Vapor–Liquid–Solid Growth of Ternary III–V Nanowires in the Presence of Silicon

by Hadi Hijazi, Mohammed Zeghouane and Vladimir G. Dubrovskii

Nanomaterials 2021, 11(1), 83; https://doi.org/10.3390/nano11010083 - 2 Jan 2021

Viewed by 2558

Abstract

Based on a thermodynamic model, we quantify the impact of adding silicon atoms to a catalyst droplet on the nucleation and growth of ternary III–V nanowires grown via the self-catalyzed vapor–liquid–solid process. Three technologically relevant ternaries are studied: InGaAs, AlGaAs and InGaN. For [...] Read more.

Based on a thermodynamic model, we quantify the impact of adding silicon atoms to a catalyst droplet on the nucleation and growth of ternary III–V nanowires grown via the self-catalyzed vapor–liquid–solid process. Three technologically relevant ternaries are studied: InGaAs, AlGaAs and InGaN. For As-based alloys, it is shown that adding silicon atoms to the droplet increases the nanowire nucleation probability, which can increase by several orders magnitude depending on the initial chemical composition of the catalyst. Conversely, silicon atoms are found to suppress the nucleation rate of InGaN nanowires of different compositions. These results can be useful for understanding and controlling the vapor–liquid–solid growth of ternary III–V nanowires on silicon substrates as well as their intentional doping with Si. Full article

(This article belongs to the Special Issue Preparation and Application of Nanowires)

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11 pages, 4366 KiB

Open AccessEditor’s ChoiceArticle

Modeling and Epitaxial Growth of Homogeneous Long-InGaN Nanowire Structures

by Sung-Un Kim and Yong-Ho Ra

Nanomaterials 2021, 11(1), 9; https://doi.org/10.3390/nano11010009 - 23 Dec 2020

Cited by 7 | Viewed by 3011

Abstract

One-dimensional nanowires based on Group III-nitride materials are emerging as one of the most promising structures for applications of light-emitting diodes (LEDs), laser diodes (LDs), solar cells, and photocatalysts. However, leading to the so-called “green gap” in photonics, the fabrication of high concentration [...] Read more.

One-dimensional nanowires based on Group III-nitride materials are emerging as one of the most promising structures for applications of light-emitting diodes (LEDs), laser diodes (LDs), solar cells, and photocatalysts. However, leading to the so-called “green gap” in photonics, the fabrication of high concentration indium gallium nitride (InGaN) and long-InGaN structures remains still challenging. In this study, we performed simulations for structural modeling of uniform temperature distribution in a nanowire epitaxy, and have successfully developed high-concentration InGaN and long-InGaN nanowire heterostructures on silicon (Si) substrate using molecular beam epitaxy (MBE) system. From scanning electron microscope (SEM) and transmission electron microscope (TEM) results, it was confirmed that the various doped-InGaN nanowire structures show much higher crystal quality compared to conventional nanowire structures. By introducing a new three-step modulated growth technique, the n-/p-InGaN active regions were greatly increased and the optical properties were also dramatically improved due to reduced phase separation. In addition, a multi-band p-InGaN/GaN heterostructure was successfully fabricated with the core–shell nanowire structures, which enable the emission of light in the entire visible spectral range, and protect the InGaN surface from surface recombination. This paper offers important insight into the design and epitaxial growth of InGaN nanowire heterostructures. Full article

(This article belongs to the Special Issue Growth and Characterization in Nanowires)

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8 pages, 1620 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

The Features of Phase Stability of GaN and AlN Films at Nanolevel

by Ilya V. Chepkasov, Sergey V. Erohin and Pavel B. Sorokin

Nanomaterials 2021, 11(1), 8; https://doi.org/10.3390/nano11010008 - 23 Dec 2020

Viewed by 2548

Abstract

Recently, two-dimensional gallium and aluminum nitrides have triggered a vast interest in their tunable optical and electronic properties. Continuation of this research requires a detailed understanding of their atomic structure. Here, by using first-principles calculations we reported a systematic study of phase stability [...] Read more.

Recently, two-dimensional gallium and aluminum nitrides have triggered a vast interest in their tunable optical and electronic properties. Continuation of this research requires a detailed understanding of their atomic structure. Here, by using first-principles calculations we reported a systematic study of phase stability of 2D-GaN and 2D-AlN. We showed that the films undergo a phase transition from a graphene-like to a wurtzite structure with a thickness increase, whereas the early reported body-centered-tetragonal phase requires specific conditions for stabilization. Additionally, we studied how the functionalization of the surface can modify the film structure as exemplified by hydrogenation. Full article

(This article belongs to the Special Issue Mechanical and Electrical Properties of Novel Nanocomposites)

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10 pages, 3300 KiB

Open AccessEditor’s ChoiceArticle

Polarization Dependent Excitation and High Harmonic Generation from Intense Mid-IR Laser Pulses in ZnO

by Richard Hollinger, Paul Herrmann, Viacheslav Korolev, Maximilian Zapf, Valentina Shumakova, Robert Röder, Ingo Uschmann, Audrius Pugžlys, Andrius Baltuška, Michael Zürch, Carsten Ronning, Christian Spielmann and Daniil Kartashov

Nanomaterials 2021, 11(1), 4; https://doi.org/10.3390/nano11010004 - 22 Dec 2020

Cited by 12 | Viewed by 4894

Abstract

The generation of high order harmonics from femtosecond mid-IR laser pulses in ZnO has shown great potential to reveal new insight into the ultrafast electron dynamics on a few femtosecond timescale. In this work we report on the experimental investigation of photoluminescence and [...] Read more.

The generation of high order harmonics from femtosecond mid-IR laser pulses in ZnO has shown great potential to reveal new insight into the ultrafast electron dynamics on a few femtosecond timescale. In this work we report on the experimental investigation of photoluminescence and high-order harmonic generation (HHG) in a ZnO single crystal and polycrystalline thin film irradiated with intense femtosecond mid-IR laser pulses. The ellipticity dependence of the HHG process is experimentally studied up to the 17th harmonic order for various driving laser wavelengths in the spectral range 3–4 µm. Interband Zener tunneling is found to exhibit a significant excitation efficiency drop for circularly polarized strong-field pump pulses. For higher harmonics with energies larger than the bandgap, the measured ellipticity dependence can be quantitatively described by numerical simulations based on the density matrix equations. The ellipticity dependence of the below and above ZnO band gap harmonics as a function of the laser wavelength provides an efficient method for distinguishing the dominant HHG mechanism for different harmonic orders. Full article

(This article belongs to the Special Issue ZnO Based Nanostructures: Synthesis, Characterization and Applications)

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17 pages, 4499 KiB

Open AccessEditor’s ChoiceArticle

Highly Sensitive Gas Sensing Material for Environmentally Toxic Gases Based on Janus NbSeTe Monolayer

by Deobrat Singh and Rajeev Ahuja

Nanomaterials 2020, 10(12), 2554; https://doi.org/10.3390/nano10122554 - 19 Dec 2020

Cited by 19 | Viewed by 3532

Abstract

Recently, a new family of the Janus NbSeTe monolayer has exciting development prospects for two-dimensional (2D) asymmetric layered materials that demonstrate outstanding properties for high-performance nanoelectronics and optoelectronics applications. Motivated by the fascinating properties of the Janus monolayer, we have studied the gas [...] Read more.

Recently, a new family of the Janus NbSeTe monolayer has exciting development prospects for two-dimensional (2D) asymmetric layered materials that demonstrate outstanding properties for high-performance nanoelectronics and optoelectronics applications. Motivated by the fascinating properties of the Janus monolayer, we have studied the gas sensing properties of the Janus NbSeTe monolayer for CO, CO

_{2}

, NO, NO

_{2}

, H

_{2}

S, and SO

_{2}

gas molecules using first-principles calculations that will have eminent application in the field of personal security, protection of the environment, and various other industries. We have calculated the adsorption energies and sensing height from the Janus NbSeTe monolayer surface to the gas molecules to detect the binding strength for these considered toxic gases. In addition, considerable charge transfer between Janus monolayer and gas molecules were calculated to confirm the detection of toxic gases. Due to the presence of asymmetric structures of the Janus NbSeTe monolayer, the projected density of states, charge transfer, binding strength, and transport properties displayed distinct behavior when these toxic gases absorbed at Se- and Te-sites of the Janus monolayer. Based on the ultra-low recovery time in the order of

μ s

for NO and NO

_{2}

and

p s

for CO, CO

_{2}

, H

_{2}

S, and SO

_{2}

gas molecules in the visible region at room temperature suggest that the Janus monolayer as a better candidate for reusable sensors for gas sensing materials. From the transport properties, it can be observed that there is a significant variation of

I - V

characteristics and sensitivity of the Janus NbSeTe monolayer before and after adsorbing gas molecules demonstrates the feasibility of NbSeTe material that makes it an ideal material for a high-sensitivity gas sensor. Full article

(This article belongs to the Special Issue Advances in Janus Nanoparticles: Synthesis, Characterization and Applications)

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15 pages, 3090 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Eco-Friendly 1,3-Dipolar Cycloaddition Reactions on Graphene Quantum Dots in Natural Deep Eutectic Solvent

by Salvatore V. Giofrè, Matteo Tiecco, Consuelo Celesti, Salvatore Patanè, Claudia Triolo, Antonino Gulino, Luca Spitaleri, Silvia Scalese, Mario Scuderi and Daniela Iannazzo

Nanomaterials 2020, 10(12), 2549; https://doi.org/10.3390/nano10122549 - 18 Dec 2020

Cited by 33 | Viewed by 3467

Abstract

Due to their outstanding physicochemical properties, the next generation of the graphene family—graphene quantum dots (GQDs)—are at the cutting edge of nanotechnology development. GQDs generally possess many hydrophilic functionalities which allow their dispersibility in water but, on the other hand, could interfere with [...] Read more.

Due to their outstanding physicochemical properties, the next generation of the graphene family—graphene quantum dots (GQDs)—are at the cutting edge of nanotechnology development. GQDs generally possess many hydrophilic functionalities which allow their dispersibility in water but, on the other hand, could interfere with reactions that are mainly performed in organic solvents, as for cycloaddition reactions. We investigated the 1,3-dipolar cycloaddition (1,3-DCA) reactions of the C-ethoxycarbonyl N-methyl nitrone 1a and the newly synthesized C-diethoxyphosphorylpropilidene N-benzyl nitrone 1b with the surface of GQDs, affording the isoxazolidine cycloadducts isox-GQDs 2a and isox-GQDs 2b. Reactions were performed in mild and eco-friendly conditions, through the use of a natural deep eutectic solvent (NADES), free of chloride or any metal ions in its composition, and formed by the zwitterionic trimethylglycine as the -bond acceptor, and glycolic acid as the hydrogen-bond donor. The results reported in this study have for the first time proved the possibility of performing cycloaddition reactions directly to the p-cloud of the GQDs surface. The use of DES for the cycloaddition reactions on GQDs, other than to improve the solubility of reactants, has been shown to bring additional advantages because of the great affinity of these green solvents with aromatic systems. Full article

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18 pages, 2788 KiB

Open AccessEditor’s ChoiceArticle

Graphene Oxides Derivatives Prepared by an Electrochemical Approach: Correlation between Structure and Properties

by Carlos Sainz-Urruela, Soledad Vera-López, María Paz San Andrés and Ana M. Díez-Pascual

Nanomaterials 2020, 10(12), 2532; https://doi.org/10.3390/nano10122532 - 17 Dec 2020

Cited by 12 | Viewed by 2452

Abstract

Graphene oxide (GO) can be defined as a single monolayer of graphite with oxygen-containing functionalities such as epoxides, alcohols, and carboxylic acids. It is an interesting alternative to graphene for many applications due to its exceptional properties and feasibility of functionalization. In this [...] Read more.

Graphene oxide (GO) can be defined as a single monolayer of graphite with oxygen-containing functionalities such as epoxides, alcohols, and carboxylic acids. It is an interesting alternative to graphene for many applications due to its exceptional properties and feasibility of functionalization. In this study, electrochemically exfoliated graphene oxides (EGOs) with different amounts of surface groups, hence level of oxidation, were prepared by an electrochemical two-stage approach using graphite as raw material. A complete characterization of the EGOs was carried out in order to correlate their surface topography, interlayer spacing, defect content, and specific surface area (SSA) with their electrical, thermal, and mechanical properties. It has been found that the SSA has a direct relationship with the d-spacing. The EGOs electrical resistance decreases with increasing SSA while rises with increasing the D/G band intensity ratio in the Raman spectra, hence the defect content. Their thermal stability under both nitrogen and dry air atmospheres depends on both their oxidation level and defect content. Their macroscopic mechanical properties, namely the Young’s modulus and tensile strength, are influenced by the defect content, while no correlation was found with their SSA or interlayer spacing. Young moduli values as high as 54 GPa have been measured, which corroborates that the developed method preserves the integrity of the graphene flakes. Understanding the structure-property relationships in these materials is useful for the design of modified GOs with controllable morphologies and properties for a wide range of applications in electrical/electronic devices. Full article

(This article belongs to the Special Issue Selected Papers from the 2nd International Online Conference on Nanomaterials)

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12 pages, 2028 KiB

Open AccessEditor’s ChoiceArticle

Calculation of Hole Concentrations in Zn Doped GaAs Nanowires

by Jonas Johansson, Masoomeh Ghasemi, Sudhakar Sivakumar, Kilian Mergenthaler, Axel R. Persson, Wondwosen Metaferia and Martin H. Magnusson

Nanomaterials 2020, 10(12), 2524; https://doi.org/10.3390/nano10122524 - 16 Dec 2020

Cited by 2 | Viewed by 2423

Abstract

We have previously demonstrated that we can grow p-type GaAs nanowires using Zn doping during gold catalyzed growth with aerotaxy. In this investigation, we show how to calculate the hole concentrations in such nanowires. We base the calculations on the Zhang–Northrup defect formation [...] Read more.

We have previously demonstrated that we can grow p-type GaAs nanowires using Zn doping during gold catalyzed growth with aerotaxy. In this investigation, we show how to calculate the hole concentrations in such nanowires. We base the calculations on the Zhang–Northrup defect formation energy. Using density functional theory, we calculate the energy of the defect, a Zn atom on a Ga site, using a supercell approach. The chemical potentials of Zn and Ga in the liquid catalyst particle are calculated from a thermodynamically assessed database including Au, Zn, Ga, and As. These quantities together with the chemical potential of the carriers enable us to calculate the hole concentration in the nanowires self-consistently. We validate our theoretical results against aerotaxy grown GaAs nanowires where we have varied the hole concentration by varying the Zn/Ga ratio in the aerotaxy growth. Full article

(This article belongs to the Special Issue Preparation and Application of Nanowires)

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11 pages, 6906 KiB

Open AccessEditor’s ChoiceArticle

Goethite Nanorods: Synthesis and Investigation of the Size Effect on Their Orientation within a Magnetic Field by SAXS

by Stephan Hinrichs, Larissa Grossmann, Eike Clasen, Hannah Grotian genannt Klages, Dieter Skroblin, Christian Gollwitzer, Andreas Meyer and Birgit Hankiewicz

Nanomaterials 2020, 10(12), 2526; https://doi.org/10.3390/nano10122526 - 16 Dec 2020

Cited by 9 | Viewed by 2826

Abstract

Goethite is a naturally anisotropic, antiferromagnetic iron oxide. Following its atomic structure, crystals grow into a fine needle shape that has interesting properties in a magnetic field. The needles align parallel to weak magnetic fields and perpendicular when subjected to high fields. We [...] Read more.

Goethite is a naturally anisotropic, antiferromagnetic iron oxide. Following its atomic structure, crystals grow into a fine needle shape that has interesting properties in a magnetic field. The needles align parallel to weak magnetic fields and perpendicular when subjected to high fields. We synthesized goethite nanorods with lengths between 200 nm and 650 nm in a two-step process. In a first step we synthesized precursor particles made of akaganeite (β-FeOOH) rods from iron(III)chloride. The precursors were then treated in a hydrothermal reactor under alkaline conditions with NaOH and polyvinylpyrrolidone (PVP) to form goethite needles. The aspect ratio was tunable between 8 and 15, based on the conditions during hydrothermal treatment. The orientation of these particles in a magnetic field was investigated by small angle X-ray scattering (SAXS). We observed that the field strength required to trigger a reorientation is dependent on the length and aspect ratio of the particles and could be shifted from 85 mT for the small particles to about 147 mT for the large particles. These particles could provide highly interesting magnetic properties to nanocomposites, that could then be used for sensing applications or membranes. Full article

(This article belongs to the Section Synthesis, Interfaces and Nanostructures)

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12 pages, 3112 KiB

Open AccessEditor’s ChoiceArticle

Various Allotropes of Diamond Nanoparticles Generated in the Gas Phase during Hot Filament Chemical Vapor Deposition

by Hwan-Young Kim, Da-Seul Kim, Kun-Su Kim and Nong-Moon Hwang

Nanomaterials 2020, 10(12), 2504; https://doi.org/10.3390/nano10122504 - 14 Dec 2020

Cited by 10 | Viewed by 3061

Abstract

Diamond nanoparticles have been synthesized using various methods. Nanodiamonds generated in the gas phase were captured on the membrane of a transmission electron microscope grid during a hot filament chemical vapor deposition (HFCVD) diamond process. In total, ~600 nanoparticles, which were captured for [...] Read more.

Diamond nanoparticles have been synthesized using various methods. Nanodiamonds generated in the gas phase were captured on the membrane of a transmission electron microscope grid during a hot filament chemical vapor deposition (HFCVD) diamond process. In total, ~600 nanoparticles, which were captured for 10 s in six conditions of the capture temperatures of 900 °C, 600 °C and 300 °C and the gas mixtures of 1% CH₄-99% H₂ and 3% CH₄-97% H₂, were analyzed for phase identification using high-resolution transmission electron microscopy and fast Fourier transformation. Hexagonal diamond, i-carbon, n-diamond, and cubic diamond were identified. The observation of two or more carbon allotropes captured on the same membrane suggested their coexistence in the gas phase during HFCVD. The crystal structure of carbon allotropes was related to the size of the nanodiamond. The crystal structure of the nanoparticles affected the crystal structure of diamond deposited for 8 h. Confirmation of various carbon allotropes provides new insight into the nanodiamond synthesis in the gas phase and the growth mechanism of HFCVD diamond. Full article

(This article belongs to the Special Issue Nanodiamonds: Synthesis, Properties, and Applications)

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15 pages, 4452 KiB

Open AccessEditor’s ChoiceArticle

2D Monomolecular Nanosheets Based on Thiacalixarene Derivatives: Synthesis, Solid State Self-Assembly and Crystal Polymorphism

by Alena A. Vavilova, Pavel L. Padnya, Timur A. Mukhametzyanov, Aleksey V. Buzyurov, Konstantin S. Usachev, Daut R. Islamov, Marat A. Ziganshin, Artur E. Boldyrev and Ivan I. Stoikov

Nanomaterials 2020, 10(12), 2505; https://doi.org/10.3390/nano10122505 - 14 Dec 2020

Cited by 4 | Viewed by 2269

Abstract

Synthetic organic 2D materials are attracting careful attention of researchers due to their excellent functionality in various applications, including storage batteries, catalysis, thermoelectricity, advanced electronics, superconductors, optoelectronics, etc. In this work, thiacalix[4]arene derivatives functionalized by geranyl fragments at the lower rim in cone [...] Read more.

Synthetic organic 2D materials are attracting careful attention of researchers due to their excellent functionality in various applications, including storage batteries, catalysis, thermoelectricity, advanced electronics, superconductors, optoelectronics, etc. In this work, thiacalix[4]arene derivatives functionalized by geranyl fragments at the lower rim in cone and 1,3-alternate conformations, that are capable of controlled self-assembly in a 2D nanostructures were synthesized. X-ray diffraction analysis showed the formation of 2D monomolecular-layer nanosheets from synthesized thiacalix[4]arenes, the distance between which depends on the stereoisomer used. It was established by DSC, FSC, and PXRD methods that the obtained macrocycles are capable of forming different crystalline polymorphs, moreover dimethyl sulphoxide (DMSO) is contributing to the formation of a more stable polymorph for cone stereoisomer. The obtained crystalline 2D materials based on synthesized thiacalix[4]arenes can find application in material science and medicine for the development of modern pharmaceuticals and new generation materials. Full article

(This article belongs to the Special Issue Design of Micro- and Nanoparticles: Self-Assembly and Application)

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11 pages, 5267 KiB

Open AccessEditor’s ChoiceArticle

Magnetic Imaging of Encapsulated Superparamagnetic Nanoparticles by Data Fusion of Magnetic Force Microscopy and Atomic Force Microscopy Signals for Correction of Topographic Crosstalk

by Marc Fuhrmann, Anna Musyanovych, Ronald Thoelen, Sibylle von Bomhard and Hildegard Möbius

Nanomaterials 2020, 10(12), 2486; https://doi.org/10.3390/nano10122486 - 11 Dec 2020

Cited by 9 | Viewed by 2613

Abstract

Encapsulated magnetic nanoparticles are of increasing interest for biomedical applications. However, up to now, it is still not possible to characterize their localized magnetic properties within the capsules. Magnetic Force Microscopy (MFM) has proved to be a suitable technique to image magnetic nanoparticles [...] Read more.

Encapsulated magnetic nanoparticles are of increasing interest for biomedical applications. However, up to now, it is still not possible to characterize their localized magnetic properties within the capsules. Magnetic Force Microscopy (MFM) has proved to be a suitable technique to image magnetic nanoparticles at ambient conditions revealing information about the spatial distribution and the magnetic properties of the nanoparticles simultaneously. However, MFM measurements on magnetic nanoparticles lead to falsifications of the magnetic MFM signal due to the topographic crosstalk. The origin of the topographic crosstalk in MFM has been proven to be capacitive coupling effects due to distance change between the substrate and tip measuring above the nanoparticle. In this paper, we present data fusion of the topography measurements of Atomic Force Microscopy (AFM) and the phase image of MFM measurements in combination with the theory of capacitive coupling in order to eliminate the topographic crosstalk in the phase image. This method offers a novel approach for the magnetic visualization of encapsulated magnetic nanoparticles. Full article

(This article belongs to the Special Issue Applications and Properties of Magnetic Nanoparticles)

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30 pages, 8807 KiB

Open AccessEditor’s ChoiceArticle

Dissolution Enhancement and Controlled Release of Paclitaxel Drug via a Hybrid Nanocarrier Based on mPEG-PCL Amphiphilic Copolymer and Fe-BTC Porous Metal-Organic Framework

by Nikolaos D. Bikiaris, Nina Maria Ainali, Evi Christodoulou, Margaritis Kostoglou, Thomas Kehagias, Emilia Papasouli, Emmanuel N. Koukaras and Stavroula G. Nanaki

Nanomaterials 2020, 10(12), 2490; https://doi.org/10.3390/nano10122490 - 11 Dec 2020

Cited by 20 | Viewed by 4431

Abstract

In the present work, the porous metal-organic framework (MOF) Basolite^®F300 (Fe-BTC) was tested as a potential drug-releasing depot to enhance the solubility of the anticancer drug paclitaxel (PTX) and to prepare controlled release formulations after its encapsulation in amphiphilic methoxy poly(ethylene [...] Read more.

In the present work, the porous metal-organic framework (MOF) Basolite^®F300 (Fe-BTC) was tested as a potential drug-releasing depot to enhance the solubility of the anticancer drug paclitaxel (PTX) and to prepare controlled release formulations after its encapsulation in amphiphilic methoxy poly(ethylene glycol)-poly(ε-caprolactone) (mPEG-PCL) nanoparticles. Investigation revealed that drug adsorption in Fe-BTC reached approximately 40%, a relatively high level, and also led to an overall drug amorphization as confirmed by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The dissolution rate of PTX-loaded MOF was substantially enhanced achieving a complete (100%) release within four days, while the neat drug only reached a 13% maximum rate (3–4 days). This PTX-Fe-BTC nanocomposite was further encapsulated into a mPEG-PCL matrix, a typical aliphatic amphiphilic copolyester synthesized in our lab, whose biocompatibility was validated by in vitro cytotoxicity tests toward human umbilical vein endothelial cells (HUVEC). Encapsulation was performed according to the solid-in-oil-in-water emulsion/solvent evaporation technique, resulting in nanoparticles of about 143 nm, slightly larger of those prepared without the pre-adsorption of PTX on Fe-BTC (138 nm, respectively). Transmission electron microscopy (TEM) imaging revealed that spherical nanoparticles with embedded PTX-loaded Fe-BTC nanoparticles were indeed fabricated, with sizes ranging from 80 to 150 nm. Regions of the composite Fe-BTC-PTX system in the infrared (IR) spectrum are identified as signatures of the drug-MOF interaction. The dissolution profiles of all nanoparticles showed an initial burst release, attributed to the drug amount located at the nanoparticles surface or close to it, followed by a steadily and controlled release. This is corroborated by computational analysis that reveals that PTX attaches effectively to Fe-BTC building blocks, but its relatively large size limits diffusion through crystalline regions of Fe-BTC. The dissolution behaviour can be described through a bimodal diffusivity model. The nanoparticles studied could serve as potential chemotherapeutic candidates for PTX delivery. Full article

(This article belongs to the Special Issue Implementation of Nanomaterials for Drug Delivery)

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12 pages, 4511 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Uranium Carbide Fibers with Nano-Grains as Starting Materials for ISOL Targets

by Sanjib Chowdhury, Leonor Maria, Adelaide Cruz, Dario Manara, Olivier Dieste-Blanco, Thierry Stora and António Pereira Gonçalves

Nanomaterials 2020, 10(12), 2458; https://doi.org/10.3390/nano10122458 - 9 Dec 2020

Cited by 4 | Viewed by 2217

Abstract

This paper presents an experimental study about the preparation, by electrospinning, of uranium carbide fibers with nanometric grain size. Viscous solutions of cellulose acetate and uranyl salts (acetate, acetylacetonate, and formate) on acetic acid and 2,4-pentanedione, adjusted to three different polymer concentrations, 10, [...] Read more.

This paper presents an experimental study about the preparation, by electrospinning, of uranium carbide fibers with nanometric grain size. Viscous solutions of cellulose acetate and uranyl salts (acetate, acetylacetonate, and formate) on acetic acid and 2,4-pentanedione, adjusted to three different polymer concentrations, 10, 12.5, and 15 weight %, were used for electrospinning. Good quality precursor fibers were obtained from solutions with a 15% cellulose acetate concentration, the best ones being produced from the uranyl acetate solution. As-spun precursor fibers were then decomposed by slow heating until 823 K under argon, resulting in a mixture of nano-grained UO₂ and C fibers. A last carboreduction was then carried out under vacuum at 2073 K for 2 h. The final material displayed UC_2−y as the major phase, with grain sizes in the 4 nm–10 nm range. UO_2+x was still present in moderate concentrations (~30 vol.%). This is due to uncomplete carboreduction that can be explained by the fiber morphology, limiting the effective contact between C and UO₂ grains. Full article

(This article belongs to the Section Nanocomposite Materials)

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12 pages, 7938 KiB

Open AccessEditor’s ChoiceArticle

Resist-Free Directed Self-Assembly Chemo-Epitaxy Approach for Line/Space Patterning

by Tommaso Jacopo Giammaria, Ahmed Gharbi, Anne Paquet, Paul Nealey and Raluca Tiron

Nanomaterials 2020, 10(12), 2443; https://doi.org/10.3390/nano10122443 - 7 Dec 2020

Cited by 3 | Viewed by 2953

Abstract

This work reports a novel, simple, and resist-free chemo-epitaxy process permitting the directed self-assembly (DSA) of lamella polystyrene-block-polymethylmethacrylate (PS-b-PMMA) block copolymers (BCPs) on a 300 mm wafer. 193i lithography is used to manufacture topographical guiding silicon oxide line/space patterns. The critical [...] Read more.

This work reports a novel, simple, and resist-free chemo-epitaxy process permitting the directed self-assembly (DSA) of lamella polystyrene-block-polymethylmethacrylate (PS-b-PMMA) block copolymers (BCPs) on a 300 mm wafer. 193i lithography is used to manufacture topographical guiding silicon oxide line/space patterns. The critical dimension (CD) of the silicon oxide line obtained can be easily trimmed by means of wet or dry etching: it allows a good control of the CD that permits finely tuning the guideline and the background dimensions. The chemical pattern that permits the DSA of the BCP is formed by a polystyrene (PS) guide and brush layers obtained with the grafting of the neutral layer polystyrene-random-polymethylmethacrylate (PS-r-PMMA). Moreover, data regarding the line edge roughness (LER) and line width roughness (LWR) are discussed with reference to the literature and to the stringent requirements of semiconductor technology. Full article

(This article belongs to the Special Issue Nanoscale Self-Assembly: Nanopatterning and Metrology)

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17 pages, 3691 KiB

Open AccessEditor’s ChoiceArticle

Deciphering the Influence of Electrolytes on the Energy Storage Mechanism of Vertically-Oriented Graphene Nanosheet Electrodes by Using Advanced Electrogravimetric Methods

by Tao Lé, Gérard Bidan, Florence Billon, Marc Delaunay, Jean-Michel Gérard, Hubert Perrot, Ozlem Sel and David Aradilla

Nanomaterials 2020, 10(12), 2451; https://doi.org/10.3390/nano10122451 - 7 Dec 2020

Viewed by 2481

Abstract

Electrolyte composition is a crucial factor determining the capacitive properties of a supercapacitor device. However, its complex influence on the energy storage mechanisms has not yet been fully elucidated. For this purpose, in this study, the role of three different types of electrolytes [...] Read more.

Electrolyte composition is a crucial factor determining the capacitive properties of a supercapacitor device. However, its complex influence on the energy storage mechanisms has not yet been fully elucidated. For this purpose, in this study, the role of three different types of electrolytes based on a propylene carbonate (PC) solution containing tetrabutylammonium perchlorate (TBAClO₄), lithium perchlorate (LiClO₄) and butyltrimethylammonium bis(trifluoromethylsulfonyl)imide (N₁₁₁₄TFSI) ionic liquid on vertically-oriented graphene nanosheet electrodes has been investigated. Herein, in situ electrochemical quartz crystal microbalance (EQCM) and its coupling with electrochemical impedance spectroscopy (EIS), known as ac-electrogravimetry, have allowed the dynamic aspects of the (co)electroadsorption processes at the electrode-electrolyte interface to be examined. A major contribution of ClO₄⁻ anions (TBAClO₄) was evidenced, whereas in the PC/N₁₁₁₄TFSI mixture (50:50 wt%) both anions (TFSI⁻) and cations (N₁₁₁₄⁺) were symmetrically exchanged during cycling. In the particular case of LiClO₄, solvation of Li⁺ cations in PC was involved, affecting the kinetics of electroadsorption. These results demonstrate the suitability of dynamic electrogravimetric methods to unveil the interfacial exchange properties of mobile species for the conception of new high performance energy storage devices. Full article

(This article belongs to the Special Issue Electrogravimetric and Electrochemical Studies on New Nanostructured Materials)

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25 pages, 3181 KiB

Open AccessEditor’s ChoiceArticle

Three-Year Study of Markers of Oxidative Stress in Exhaled Breath Condensate in Workers Producing Nanocomposites, Extended by Plasma and Urine Analysis in Last Two Years

by Daniela Pelclova, Vladimir Zdimal, Martin Komarc, Jaroslav Schwarz, Jakub Ondracek, Lucie Ondrackova, Martin Kostejn, Stepanka Vlckova, Zdenka Fenclova, Stepanka Dvorackova, Lucie Lischkova, Pavlina Klusackova, Viktoriia Kolesnikova, Andrea Rossnerova and Tomas Navratil

Nanomaterials 2020, 10(12), 2440; https://doi.org/10.3390/nano10122440 - 6 Dec 2020

Cited by 23 | Viewed by 2759

Abstract

Human data concerning exposure to nanoparticles are very limited, and biomarkers for monitoring exposure are urgently needed. In a follow-up of a 2016 study in a nanocomposites plant, in which only exhaled breath condensate (EBC) was examined, eight markers of oxidative stress were [...] Read more.

Human data concerning exposure to nanoparticles are very limited, and biomarkers for monitoring exposure are urgently needed. In a follow-up of a 2016 study in a nanocomposites plant, in which only exhaled breath condensate (EBC) was examined, eight markers of oxidative stress were analyzed in three bodily fluids, i.e., EBC, plasma and urine, in both pre-shift and post-shift samples in 2017 and 2018. Aerosol exposures were monitored. Mass concentration in 2017 was 0.351 mg/m³ during machining, and 0.179 and 0.217 mg/m³ during machining and welding, respectively, in 2018. In number concentrations, nanoparticles formed 96%, 90% and 59%, respectively. In both years, pre-shift elevations of 50.0% in EBC, 37.5% in plasma and 6.25% in urine biomarkers were observed. Post-shift elevation reached 62.5% in EBC, 68.8% in plasma and 18.8% in urine samples. The same trend was observed in all biological fluids. Individual factors were responsible for the elevation of control subjects’ afternoon vs. morning markers in 2018; all were significantly lower compared to those of workers. Malondialdehyde levels were always acutely shifted, and 8-hydroxy-2-deoxyguanosine levels best showed chronic exposure effect. EBC and plasma analysis appear to be the ideal fluids for bio-monitoring of oxidative stress arising from engineered nanomaterials. Potential late effects need to be targeted and prevented, as there is a similarity of EBC findings in patients with silicosis and asbestosis. Full article

(This article belongs to the Special Issue Frontiers in Nanotoxicology)

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23 pages, 5938 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Photosensitive Thin Films Based on Drop Cast and Langmuir-Blodgett Hydrophilic and Hydrophobic CdS Nanoparticles

by Momoka Nagamine, Magdalena Osial, Justyna Widera-Kalinowska, Krystyna Jackowska and Paweł Krysiński

Nanomaterials 2020, 10(12), 2437; https://doi.org/10.3390/nano10122437 - 5 Dec 2020

Cited by 7 | Viewed by 2626

Abstract

Comparative photoelectrochemical studies of cadmium sulfide (CdS) nanoparticles with either hydrophilic or hydrophobic surface properties are presented. Oleylamine organic shells provided CdS nanoparticles with hydrophobic behavior, affecting the photoelectrochemical properties of such nanostructured semiconductor. Hydrophilic CdS nanoparticles were drop-cast on the electrode, whereas [...] Read more.

Comparative photoelectrochemical studies of cadmium sulfide (CdS) nanoparticles with either hydrophilic or hydrophobic surface properties are presented. Oleylamine organic shells provided CdS nanoparticles with hydrophobic behavior, affecting the photoelectrochemical properties of such nanostructured semiconductor. Hydrophilic CdS nanoparticles were drop-cast on the electrode, whereas the hydrophobic ones were transferred in a controlled manner with Langmuir-Blodgett technique. The substantial hindrance of photopotential and photocurrent was observed for L-B CdS films as compared to the hydrophilic, uncoated nanoparticles that were drop-cast directly on the electrode surface. The electron lifetime in both hydrophilic and hydrophobic nanocrystalline CdS was determined, revealing longer carrier lifetime for oleylamine coated CdS nanoparticles, ascribed to the trapping of charge at the interface of the organic shell/CdS nanoparticle and to the dominant influence of the resistance of the organic shell against the flux of charges. The “on” transients of the photocurrent responses, observed only for the oleylamine-coated nanoparticles, were resolved, yielding the potential-dependent rate constants of the redox processes occurring at the interface. Full article

(This article belongs to the Special Issue Synthesis and Functionalization of Colloidal Nanoparticles)

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12 pages, 3382 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Electrical Conduction Behavior of High-Performance Microcellular Nanocomposites Made of Graphene Nanoplatelet-Filled Polysulfone

by Hooman Abbasi, Marcelo Antunes and José Ignacio Velasco

Nanomaterials 2020, 10(12), 2425; https://doi.org/10.3390/nano10122425 - 4 Dec 2020

Cited by 3 | Viewed by 1950

Abstract

Graphene nanoplatelet (GnP)-filled polysulfone (PSU) cellular nanocomposites, prepared by two different methods—namely, water vapor-induced phase separation (WVIPS) and supercritical CO₂ dissolution (scCO₂) foaming—were produced with a range of densities from 0.4 to 0.6 g/cm³ and characterized in terms of [...] Read more.

Graphene nanoplatelet (GnP)-filled polysulfone (PSU) cellular nanocomposites, prepared by two different methods—namely, water vapor-induced phase separation (WVIPS) and supercritical CO₂ dissolution (scCO₂) foaming—were produced with a range of densities from 0.4 to 0.6 g/cm³ and characterized in terms of their structure and electrical conduction behavior. The GnP content was varied from 0 to 10 wt%. The electrical conductivity values were increased with the amount of GnP for the three different studied foam series. The highest values were found for the microcellular nanocomposites prepared by the WVIPS method, reaching as high as 8.17 × 10⁻² S/m for 10 wt% GnP. The variation trend of the electrical conductivity for each series was analyzed by applying both the percolation and the tunneling models. Comparatively, the tunneling model showed a better fitting in the prediction of the electrical conductivity. The preparation technique of the cellular nanocomposite affected the resultant cellular structure of the nanocomposite and, as a result, the porosity or gas volume fraction (V_g). A higher porosity resulted in a higher electrical conductivity, with the lightest foams being prepared by the WVIPS method, showing electrical conductivities two orders of magnitude higher than the equivalent foams prepared by the scCO₂ dissolution technique. Full article

(This article belongs to the Special Issue Multifunctional Polymer-Based Nanocomposite Materials)

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18 pages, 3322 KiB

Open AccessEditor’s ChoiceArticle

Electrostatic Design of Polar Metal–Organic Framework Thin Films

by Giulia Nascimbeni, Christof Wöll and Egbert Zojer

Nanomaterials 2020, 10(12), 2420; https://doi.org/10.3390/nano10122420 - 3 Dec 2020

Cited by 8 | Viewed by 3294

Abstract

In recent years, optical and electronic properties of metal–organic frameworks (MOFs) have increasingly shifted into the focus of interest of the scientific community. Here, we discuss a strategy for conveniently tuning these properties through electrostatic design. More specifically, based on quantum-mechanical simulations, we [...] Read more.

In recent years, optical and electronic properties of metal–organic frameworks (MOFs) have increasingly shifted into the focus of interest of the scientific community. Here, we discuss a strategy for conveniently tuning these properties through electrostatic design. More specifically, based on quantum-mechanical simulations, we suggest an approach for creating a gradient of the electrostatic potential within a MOF thin film, exploiting collective electrostatic effects. With a suitable orientation of polar apical linkers, the resulting non-centrosymmetric packing results in an energy staircase of the frontier electronic states reminiscent of the situation in a pin-photodiode. The observed one dimensional gradient of the electrostatic potential causes a closure of the global energy gap and also shifts core-level energies by an amount equaling the size of the original band gap. The realization of such assemblies could be based on so-called pillared layer MOFs fabricated in an oriented fashion on a solid substrate employing layer by layer growth techniques. In this context, the simulations provide guidelines regarding the design of the polar apical linker molecules that would allow the realization of MOF thin films with the (vast majority of the) molecular dipole moments pointing in the same direction. Full article

(This article belongs to the Section Inorganic Materials and Metal-Organic Frameworks)

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21 pages, 30592 KiB

Open AccessEditor’s ChoiceArticle

Creation of Gold Nanoparticles in ZnO by Ion Implantation–DFT and Experimental Studies

by Jakub Cajzl, Karla Jeníčková, Pavla Nekvindová, Alena Michalcová, Martin Veselý, Anna Macková, Petr Malinský, Adéla Jágerová, Romana Mikšová and Shavkat Akhmadaliev

Nanomaterials 2020, 10(12), 2392; https://doi.org/10.3390/nano10122392 - 30 Nov 2020

Cited by 11 | Viewed by 3035

Abstract

Three different crystallographic orientations of the wurtzite ZnO structure (labeled as c-plane, a-plane and m-plane) were implanted with Au⁺ ions using various energies and fluences to form gold nanoparticles (GNPs). The ion implantation process was followed by annealing at [...] Read more.

Three different crystallographic orientations of the wurtzite ZnO structure (labeled as c-plane, a-plane and m-plane) were implanted with Au⁺ ions using various energies and fluences to form gold nanoparticles (GNPs). The ion implantation process was followed by annealing at 600 °C in an oxygen atmosphere to decrease the number of unwanted defects and improve luminescence properties. With regard to our previous publications, the paper provides a summary of theoretical and experimental results, i.e., both DFT and FLUX simulations, as well as experimental results from TEM, HRTEM, RBS, RBS/C, Raman spectroscopy and photoluminescence. From the results, it follows that in the ZnO structure, implanted gold atoms are located in random interstitial positions —experimentally, the amount of interstitial gold atoms increased with increasing ion implantation fluence. During ion implantation and subsequent annealing, the metal clusters and nanoparticles with sizes from 2 to 20 nm were formed. The crystal structure of the resulting gold was not cubic (confirmed by diffraction patterns), but it had a hexagonal close-packed (hcp) arrangement. The ion implantation of gold leads to the creation of Zn and O interstitial defects and extended defects with distinct character in various crystallographic cuts of ZnO, where significant O-sublattice disordering occurred in m-plane ZnO. Full article

(This article belongs to the Section Synthesis, Interfaces and Nanostructures)

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10 pages, 1615 KiB

Open AccessEditor’s ChoiceArticle

Band Gap Measurements of Nano-Meter Sized Rutile Thin Films

by Nikolaos C. Diamantopoulos, Alexandros Barnasas, Christos. S. Garoufalis, Dimitrios I. Anyfantis, Nikolaos Bouropoulos, Panagiotis Poulopoulos and Sotirios Baskoutas

Nanomaterials 2020, 10(12), 2379; https://doi.org/10.3390/nano10122379 - 29 Nov 2020

Cited by 18 | Viewed by 2752

Abstract

Thin Titanium films were fabricated on quartz substrates by radio frequency magnetron sputtering under high vacuum. Subsequent annealing at temperatures of 600

^{\circ}

C in air resulted in single-phase

{T i O}_{2}

with the structure of rutile, as X-ray diffraction experiment demonstrates. [...] Read more.

Thin Titanium films were fabricated on quartz substrates by radio frequency magnetron sputtering under high vacuum. Subsequent annealing at temperatures of 600

^{\circ}

C in air resulted in single-phase

{T i O}_{2}

with the structure of rutile, as X-ray diffraction experiment demonstrates. Atomic-force microscopy images verify the high crystalline quality and allow us to determine the grain size even for ultrathin

{T i O}_{2}

films. Rutile has a direct energy band gap at about 3.0–3.2 eV; however, the transitions between the valence and conduction band are dipole forbidden. Just a few meV above that, there is an indirect band gap. The first intense absorption peak appears at about 4 eV. Tauc plots for the position of the indirect band gap show a “blue shift” with decreasing film thickness. Moreover, we find a similar shift for the position of the first absorbance peak studied by the derivative method. The results indicate the presence of quantum confinement effects. This conclusion is supported by theoretical calculations based on a combination of the effective mass theory and the Hartree Fock approximation. Full article

(This article belongs to the Section Nanocomposite Materials)

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17 pages, 5301 KiB

Open AccessEditor’s ChoiceArticle

Sulfate-Containing Composite Based on Ni-Rich Layered Oxide LiNi_0.8Mn_0.1Co_0.1O₂ as High-Performance Cathode Material for Li-ion Batteries

by Aleksandra A. Savina, Elena D. Orlova, Anatolii V. Morozov, Sergey Yu. Luchkin and Artem M. Abakumov

Nanomaterials 2020, 10(12), 2381; https://doi.org/10.3390/nano10122381 - 29 Nov 2020

Cited by 16 | Viewed by 4862

Abstract

Composite positive electrode materials (1−x) LiNi_0.8Mn_0.1Co_0.1O₂∙xLi₂SO₄ (x = 0.002–0.005) for Li-ion batteries have been synthesized via conventional hydroxide or carbonate coprecipitation routes with subsequent high-temperature lithiation in [...] Read more.

Composite positive electrode materials (1−x) LiNi_0.8Mn_0.1Co_0.1O₂∙xLi₂SO₄ (x = 0.002–0.005) for Li-ion batteries have been synthesized via conventional hydroxide or carbonate coprecipitation routes with subsequent high-temperature lithiation in either air or oxygen atmosphere. A comparative study of the materials prepared from transition metal sulfates (i.e., containing sulfur) and acetates (i.e., sulfur-free) with powder X-ray diffraction, electron diffraction, high angle annular dark field transmission electron microscopy, energy-dispersive X-ray spectroscopy, and electron energy loss spectroscopy revealed that the sulfur-containing species occur as amorphous Li₂SO₄ at the grain boundaries and intergranular contacts of the primary NMC811 crystallites. This results in a noticeable enhancement of rate capability and capacity retention over prolonged charge/discharge cycling compared to their sulfur-free analogs. The improvement is attributed to suppressing the high voltage phase transition and the associated accumulation of anti-site disorder upon cycling and improving the secondary agglomerates’ mechanical integrity by increasing interfacial fracture toughness through linking primary NMC811 particles with soft Li₂SO₄ binder, as demonstrated with nanoindentation experiments. As the synthesis of the (1−x) LiNi_0.8Mn_0.1Co_0.1O₂∙xLi₂SO₄ composites do not require additional operational steps to introduce sulfur, these electrode materials might demonstrate high potential for commercialization. Full article

(This article belongs to the Section Energy and Catalysis)

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11 pages, 3014 KiB

Open AccessEditor’s ChoiceArticle

Silicon-Carbide (SiC) Nanocrystal Technology and Characterization and Its Applications in Memory Structures

by Andrzej Mazurak, Robert Mroczyński, David Beke and Adam Gali

Nanomaterials 2020, 10(12), 2387; https://doi.org/10.3390/nano10122387 - 29 Nov 2020

Cited by 8 | Viewed by 3379

Abstract

Colloidal cubic silicon-carbide nanocrystals have been fabricated, characterized, and introduced into metal–insulator–semiconductor and metal–insulator–metal structures based on hafnium oxide layers. The fabricated structures were characterized through the stress-and-sense measurements in terms of device capacitance, flat-band voltage shift, switching characteristics, and retention time. The [...] Read more.

Colloidal cubic silicon-carbide nanocrystals have been fabricated, characterized, and introduced into metal–insulator–semiconductor and metal–insulator–metal structures based on hafnium oxide layers. The fabricated structures were characterized through the stress-and-sense measurements in terms of device capacitance, flat-band voltage shift, switching characteristics, and retention time. The examined electrical performance of the sample structures has demonstrated the feasibility of the application of both types of structures based on SiC nanoparticles in memory devices. Full article

(This article belongs to the Special Issue Nanomaterials Based on IV-Group Semiconductors)

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22 pages, 4336 KiB

Open AccessEditor’s ChoiceArticle

Strategies for Controlling Through-Space Charge Transport in Metal-Organic Frameworks via Structural Modifications

by Christian Winkler and Egbert Zojer

Nanomaterials 2020, 10(12), 2372; https://doi.org/10.3390/nano10122372 - 28 Nov 2020

Cited by 5 | Viewed by 3699

Abstract

In recent years, charge transport in metal-organic frameworks (MOFs) has shifted into the focus of scientific research. In this context, systems with efficient through-space charge transport pathways resulting from π-stacked conjugated linkers are of particular interest. In the current manuscript, we use [...] Read more.

In recent years, charge transport in metal-organic frameworks (MOFs) has shifted into the focus of scientific research. In this context, systems with efficient through-space charge transport pathways resulting from π-stacked conjugated linkers are of particular interest. In the current manuscript, we use density functional theory-based simulations to provide a detailed understanding of such MOFs, which, in the present case, are derived from the prototypical Zn₂(TTFTB) system (with TTFTB⁴⁻ corresponding to tetrathiafulvalene tetrabenzoate). In particular, we show that factors such as the relative arrangement of neighboring linkers and the details of the structural conformations of the individual building blocks have a profound impact on bandwidths and charge transfer. Considering the helical stacking of individual tetrathiafulvalene (TTF) molecules around a screw axis as the dominant symmetry element in Zn₂(TTFTB)-derived materials, the focus, here, is primarily on the impact of the relative rotation of neighboring molecules. Not unexpectedly, changing the stacking distance in the helix also plays a distinct role, especially for structures which display large electronic couplings to start with. The presented results provide guidelines for achieving structures with improved electronic couplings. It is, however, also shown that structural defects (especially missing linkers) provide major obstacles to charge transport in the studied, essentially one-dimensional systems. This suggests that especially the sample quality is a decisive factor for ensuring efficient through-space charge transport in MOFs comprising stacked π-systems. Full article

(This article belongs to the Section Inorganic Materials and Metal-Organic Frameworks)

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25 pages, 3697 KiB

Open AccessEditor’s ChoiceArticle

Parametric Optimization of an Air–Liquid Interface System for Flow-Through Inhalation Exposure to Nanoparticles: Assessing Dosimetry and Intracellular Uptake of CeO₂ Nanoparticles

by Lars B. Leibrock, Harald Jungnickel, Jutta Tentschert, Aaron Katz, Blaza Toman, Elijah J. Petersen, Frank S. Bierkandt, Ajay Vikram Singh, Peter Laux and Andreas Luch

Nanomaterials 2020, 10(12), 2369; https://doi.org/10.3390/nano10122369 - 28 Nov 2020

Cited by 28 | Viewed by 4459

Abstract

Air–liquid interface (ALI) systems have been widely used in recent years to investigate the inhalation toxicity of many gaseous compounds, chemicals, and nanomaterials and represent an emerging and promising in vitro method to supplement in vivo studies. ALI exposure reflects the physiological conditions [...] Read more.

Air–liquid interface (ALI) systems have been widely used in recent years to investigate the inhalation toxicity of many gaseous compounds, chemicals, and nanomaterials and represent an emerging and promising in vitro method to supplement in vivo studies. ALI exposure reflects the physiological conditions of the deep lung more closely to subacute in vivo inhalation scenarios compared to submerged exposure. The comparability of the toxicological results obtained from in vivo and in vitro inhalation data is still challenging. The robustness of ALI exposure scenarios is not yet well understood, but critical for the potential standardization of these methods. We report a cause-and-effect (C&E) analysis of a flow through ALI exposure system. The influence of five different instrumental and physiological parameters affecting cell viability and exposure parameters of a human lung cell line in vitro (exposure duration, relative humidity, temperature, CO₂ concentration and flow rate) was investigated. After exposing lung epithelia cells to a CeO₂ nanoparticle (NP) aerosol, intracellular CeO₂ concentrations reached values similar to those found in a recent subacute rat inhalation study in vivo. This is the first study showing that the NP concentration reached in vitro using a flow through ALI system were the same as those in an in vivo study. Full article

(This article belongs to the Special Issue Design, Development, and Production of Nanocarriers and Nanovehicles)

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24 pages, 2329 KiB

Open AccessEditor’s ChoiceArticle

Development of Active Barrier Multilayer Films Based on Electrospun Antimicrobial Hot-Tack Food Waste Derived Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and Cellulose Nanocrystal Interlayers

by Kelly J. Figueroa-Lopez, Sergio Torres-Giner, Inmaculada Angulo, Maria Pardo-Figuerez, Jose Manuel Escuin, Ana Isabel Bourbon, Luis Cabedo, Yuval Nevo, Miguel A. Cerqueira and Jose M. Lagaron

Nanomaterials 2020, 10(12), 2356; https://doi.org/10.3390/nano10122356 - 27 Nov 2020

Cited by 32 | Viewed by 10251

Abstract

Active multilayer films based on polyhydroxyalkanoates (PHAs) with and without high barrier coatings of cellulose nanocrystals (CNCs) were herein successfully developed. To this end, an electrospun antimicrobial hot-tack layer made of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) derived from cheese whey, a by-product from the [...] Read more.

Active multilayer films based on polyhydroxyalkanoates (PHAs) with and without high barrier coatings of cellulose nanocrystals (CNCs) were herein successfully developed. To this end, an electrospun antimicrobial hot-tack layer made of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) derived from cheese whey, a by-product from the dairy industry, was deposited on a previously manufactured blown film of commercial food contact PHA-based resin. A hybrid combination of oregano essential oil (OEO) and zinc oxide nanoparticles (ZnONPs) were incorporated during the electrospinning process into the PHBV nanofibers at 2.5 and 2.25 wt%, respectively, in order to provide antimicrobial properties. A barrier CNC coating was also applied by casting from an aqueous solution of nanocellulose at 2 wt% using a rod at 1m/min. The whole multilayer structure was thereafter assembled in a pilot roll-to-roll laminating system, where the blown PHA-based film was located as the outer layers while the electrospun antimicrobial hot-tack PHBV layer and the barrier CNC coating were placed as interlayers. The resultant multilayer films, having a final thickness in the 130–150 µm range, were characterized to ascertain their potential in biodegradable food packaging. The multilayers showed contact transparency, interlayer adhesion, improved barrier to water and limonene vapors, and intermediate mechanical performance. Moreover, the films presented high antimicrobial and antioxidant activities in both open and closed systems for up to 15 days. Finally, the food safety of the multilayers was assessed by migration and cytotoxicity tests, demonstrating that the films are safe to use in both alcoholic and acid food simulants and they are also not cytotoxic for Caco-2 cells. Full article

(This article belongs to the Special Issue Advances in Food Nanotechnology)

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11 pages, 514 KiB

Open AccessEditor’s ChoiceArticle

A Legendre–Fenchel Transform for Molecular Stretching Energies

by Eivind Bering, Dick Bedeaux, Signe Kjelstrup, Astrid S. de Wijn, Ivan Latella and J. Miguel Rubi

Nanomaterials 2020, 10(12), 2355; https://doi.org/10.3390/nano10122355 - 27 Nov 2020

Cited by 7 | Viewed by 2142

Abstract

Single-molecular polymers can be used to analyze to what extent thermodynamics applies when the size of the system is drastically reduced. We have recently verified using molecular-dynamics simulations that isometric and isotensional stretching of a small polymer result in Helmholtz and Gibbs stretching [...] Read more.

Single-molecular polymers can be used to analyze to what extent thermodynamics applies when the size of the system is drastically reduced. We have recently verified using molecular-dynamics simulations that isometric and isotensional stretching of a small polymer result in Helmholtz and Gibbs stretching energies, which are not related to a Legendre transform, as they are for sufficiently long polymers. This disparity has also been observed experimentally. Using molecular dynamics simulations of polyethylene-oxide, we document for the first time that the Helmholtz and Gibbs stretching energies can be related by a Legendre–Fenchel transform. This opens up a possibility to apply this transform to other systems which are small in Hill’s sense. Full article

(This article belongs to the Special Issue Nanoscale Thermodynamics)

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14 pages, 3596 KiB

Open AccessEditor’s ChoiceArticle

Enhancing and Tuning the Nonlinear Optical Response and Wavelength-Agile Strong Optical Limiting Action of N-octylamine Modified Fluorographenes

by Aristeidis Stathis, Michalis Stavrou, Ioannis Papadakis, Ievgen Obratzov and Stelios Couris

Nanomaterials 2020, 10(11), 2319; https://doi.org/10.3390/nano10112319 - 23 Nov 2020

Cited by 8 | Viewed by 2819

Abstract

Fluorographene has been recently shown to be a suitable platform for synthesizing numerous graphene derivatives with desired properties. In that respect, N-octylamine-modified fluorographenes with variable degrees of functionalization are studied and their nonlinear optical properties are assessed using 4 ns pulses. A [...] Read more.

Fluorographene has been recently shown to be a suitable platform for synthesizing numerous graphene derivatives with desired properties. In that respect, N-octylamine-modified fluorographenes with variable degrees of functionalization are studied and their nonlinear optical properties are assessed using 4 ns pulses. A very strong enhancement of the nonlinear optical response and a very efficient optical limiting action are observed, being strongly dependent on the degree of functionalization of fluorographene. The observed enhanced response is attributed to the increasing number of defects because of the incorporation of N-heteroatoms in the graphitic network upon functionalization with N-octylamine. The present work paves the way for the controlled covalent functionalization of graphene enabling a scalable access to a wide portfolio of graphene derivatives with custom-tailored properties. Full article

(This article belongs to the Special Issue Nanomaterials for Nanophotonics, Nonlinear Optical and Energy Applications)

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13 pages, 4210 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

CO₂ Adsorption in Metal-Organic Framework Mg-MOF-74: Effects of Inter-Crystalline Space

by Siddharth Gautam and David Cole

Nanomaterials 2020, 10(11), 2274; https://doi.org/10.3390/nano10112274 - 17 Nov 2020

Cited by 21 | Viewed by 9072

Abstract

Metal-Organic Frameworks (MOF) have been identified as highly efficient nanoporous adsorbents for CO₂ storage. In particular, Mg-MOF-74 has been shown to promise exceptionally high CO₂ sorption. Although several studies have reported adsorption isotherms of CO₂ in Mg-MOF-74, the effect of [...] Read more.

Metal-Organic Frameworks (MOF) have been identified as highly efficient nanoporous adsorbents for CO₂ storage. In particular, Mg-MOF-74 has been shown to promise exceptionally high CO₂ sorption. Although several studies have reported adsorption isotherms of CO₂ in Mg-MOF-74, the effect of inter-crystalline spacing in Mg-MOF-74 on the sorption of CO₂ has not been addressed. These effects have been shown to be profound for a quadrupolar molecule like CO₂ in the case of silicalite (Phys. Chem. Chem. Phys. 22 (2020) 13951). Here, we report the effects of inter-crystalline spacing on the adsorption of CO₂ in Mg-MOF-74, studied using grand canonical Monte Carlo (GCMC) simulations. The inter-crystalline spacing is found to enhance adsorption at the crystallite surfaces. Larger inter-crystalline spacing up to twice the kinetic diameter of CO₂ results in higher adsorption and larger crystallite sizes suppress adsorption. Magnitudes of the inter-crystalline space relative to the kinetic diameter of the adsorbed fluid and the surface to volume ratio of the adsorbent crystallites are found to be important factors determining the adsorption amounts. The results of this study suggest that the ideal Mg-MOF-74 sample for CO₂ storage applications should have smaller crystallites separated from each other with an inter-crystalline space of approximately twice the kinetic diameter of CO₂. Full article

(This article belongs to the Section Inorganic Materials and Metal-Organic Frameworks)

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13 pages, 4519 KiB

Open AccessEditor’s ChoiceArticle

Synthesis, Structure and Electrical Resistivity of Carbon Nanotubes Synthesized over Group VIII Metallocenes

by Aida R. Karaeva, Sergey A. Urvanov, Nikita V. Kazennov, Eduard B. Mitberg and Vladimir Z. Mordkovich

Nanomaterials 2020, 10(11), 2279; https://doi.org/10.3390/nano10112279 - 17 Nov 2020

Cited by 15 | Viewed by 3160

Abstract

The paper reports the synthesis of carbon nanotubes from ethanol over group VIII (Fe, Co, Ni) catalysts derived from corresponding metallocenes. Several unexpected cooperative effects are reported, which are never observed in the case of individual metallocenes such as the commonly used ferrocene [...] Read more.

The paper reports the synthesis of carbon nanotubes from ethanol over group VIII (Fe, Co, Ni) catalysts derived from corresponding metallocenes. Several unexpected cooperative effects are reported, which are never observed in the case of individual metallocenes such as the commonly used ferrocene catalyst Fe(C₅H₅)₂. The formation of very long (up to several µm) straight monocrystal metal kernels inside the carbon nanotubes was the most interesting effect. The use of trimetal catalysts (Fe_1-x-yCo_xNi_y)(C₅H₅)₂ resulted in the sharp increase in the yield of carbon nanotubes. The electrical conductivity of the produced nanotubes is determined by the nature of the catalyst. The variation of individual metals in the Ni-Co-Fe leads to a drop of the electrical resistivity of nanotube samples by the order of magnitude, i.e., from 1.0 × 10⁻³ to 1.1 × 10⁻⁵ Ω∙m. A controlled change in the electrophysical properties of the nanotubes can make it possible to expand their use as fillers in composites, photothermal and tunable magnetic nanomaterials with pre-designed electrical conductivity and other electromagnetic properties. Full article

(This article belongs to the Special Issue Mechanical and Electrical Properties of Novel Nanocomposites)

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12 pages, 3421 KiB

Open AccessEditor’s ChoiceArticle

Effects of Mg and Sb Substitution on the Magnetic Properties of Magnetic Field Annealed MnBi Alloys

by Hui-Dong Qian, Yang Yang, Jung Tae Lim, Jong-Woo Kim, Chul-Jin Choi and Jihoon Park

Nanomaterials 2020, 10(11), 2265; https://doi.org/10.3390/nano10112265 - 16 Nov 2020

Cited by 9 | Viewed by 2843

Abstract

Rare-earth-free permanent magnets have attracted considerable attention due to their favorable properties and applicability for cost-effective, high-efficiency, and sustainable energy devices. However, the magnetic field annealing process, which enhances the performance of permanent magnets, needs to be optimized for different magnetic fields and [...] Read more.

Rare-earth-free permanent magnets have attracted considerable attention due to their favorable properties and applicability for cost-effective, high-efficiency, and sustainable energy devices. However, the magnetic field annealing process, which enhances the performance of permanent magnets, needs to be optimized for different magnetic fields and phases. Therefore, we investigated the effect of composition on the crystallization of amorphous MnBi to the ferromagnetic low-temperature phase (LTP). The optimal compositions and conditions were applied to magnetic field annealing under 2.5 T for elemental Mg- and Sb/Mg pair-substituted MnBi. The optimum MnBi composition for the highest purity LTP was determined to be Mn₅₆Bi₄₄, and its maximum energy product, (BH)_max, was 5.62 MGOe. The Mg-substituted MnBi exhibited enhanced squareness (M_r/M_s), coercivity (H_c), and (BH)_max values up to 0.8, 9659 Oe, and 5.64 MGOe, respectively, whereas the same values for the Sb/Mg pair-substituted MnBi were 0.76, 7038 Oe, and 5.60 MGOe, respectively. The substitution effects were also investigated using first-principles calculations. The density of states and total magnetic moments of Mn₁₆Bi₁₅Mg and Mn₁₆Bi₁₅Sb were similar to those of pure Mn₁₆Bi₁₆. Conversely, the Sb-substituted MnBi resulted in a dramatic enhancement in the anisotropy constant (K) from a small negative value (−0.85 MJ/m³) to a large positive value (6.042 MJ/m³). Full article

(This article belongs to the Special Issue Synthesis and Properties of Nanocrystalline Magnetic Materials)

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8 pages, 3931 KiB

Open AccessEditor’s ChoiceArticle

Effect of ZnO and SnO₂ Nanolayers at Grain Boundaries on Thermoelectric Properties of Polycrystalline Skutterudites

by Sang-il Kim, Jiwoo An, Woo-Jae Lee, Se Hun Kwon, Woo Hyun Nam, Nguyen Van Du, Jong-Min Oh, Sang-Mo Koo, Jung Young Cho and Weon Ho Shin

Nanomaterials 2020, 10(11), 2270; https://doi.org/10.3390/nano10112270 - 16 Nov 2020

Cited by 6 | Viewed by 2523

Abstract

Nanostructuring is considered one of the key approaches to achieve highly efficient thermoelectric alloys by reducing thermal conductivity. In this study, we investigated the effect of oxide (ZnO and SnO₂) nanolayers at the grain boundaries of polycrystalline In_0.2Yb_0.1 [...] Read more.

Nanostructuring is considered one of the key approaches to achieve highly efficient thermoelectric alloys by reducing thermal conductivity. In this study, we investigated the effect of oxide (ZnO and SnO₂) nanolayers at the grain boundaries of polycrystalline In_0.2Yb_0.1Co₄Sb₁₂ skutterudites on their electrical and thermal transport properties. Skutterudite powders with oxide nanolayers were prepared by atomic layer deposition method, and the number of deposition cycles was varied to control the coating thickness. The coated powders were consolidated by spark plasma sintering. With increasing number of deposition cycle, the electrical conductivity gradually decreased, while the Seebeck coefficient changed insignificantly; this indicates that the carrier mobility decreased due to the oxide nanolayers. In contrast, the lattice thermal conductivity increased with an increase in the number of deposition cycles, demonstrating the reduction in phonon scattering by grain boundaries owing to the oxide nanolayers. Thus, we could easily control the thermoelectric properties of skutterudite materials through adjusting the oxide nanolayer by atomic layer deposition method. Full article

(This article belongs to the Special Issue Nanotechnology for Green Chemical Engineering)

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16 pages, 4741 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Langmuir Films of Perfluorinated Fatty Alcohols: Evidence of Spontaneous Formation of Solid Aggregates at Zero Surface Pressure and Very Low Surface Density

by Pedro Silva, Duarte Nova, Miguel Teixeira, Vitória Cardoso, Pedro Morgado, Bruno Nunes, Rogério Colaço, Marie-Claude Fauré, Philippe Fontaine, Michel Goldmann and Eduardo J. M. Filipe

Nanomaterials 2020, 10(11), 2257; https://doi.org/10.3390/nano10112257 - 14 Nov 2020

Cited by 6 | Viewed by 3197

Abstract

In this work, Langmuir films of two highly fluorinated fatty alcohols, CF₃(CF₂)₁₂CH₂OH (F14OH) and CF₃(CF₂)₁₆CH₂OH (F18OH), were studied. Atomic Force Microscopy (AFM) images of the films transferred [...] Read more.

In this work, Langmuir films of two highly fluorinated fatty alcohols, CF₃(CF₂)₁₂CH₂OH (F14OH) and CF₃(CF₂)₁₆CH₂OH (F18OH), were studied. Atomic Force Microscopy (AFM) images of the films transferred at zero surface pressure and low surface density onto the surface of silicon wafers by the Langmuir-Blodgett technique revealed, for the first time, the existence of solid-like domains with well-defined mostly hexagonal (starry) shapes in the case of F18OH, and with an entangled structure of threads in the case of F14OH. A (20:80) molar mixture of the two alcohols displayed a surprising combination of the two patterns: hexagonal domains surrounded by zigzagging threads, clearly demonstrating that the two alcohols segregate during the 2D crystallization process. Grazing Incidence X-ray Diffraction (GIXD) measurements confirmed that the molecules of both alcohols organize in 2D hexagonal lattices. Atomistic Molecular Dynamics (MD) simulations provide a visualization of the structure of the domains and allow a molecular-level interpretation of the experimental observations. The simulation results clearly showed that perfluorinated alcohols have an intrinsic tendency to aggregate, even at very low surface density. The formed domains are highly organized compared to those of hydrogenated alcohols with similar chain length. Very probably, this tendency is a consequence of the characteristic stiffness of the perfluorinated chains. The diffraction spectrum calculated from the simulation trajectories compares favorably with the experimental spectra, fully validating the simulations and the proposed interpretation. The present results highlight for the first time an inherent tendency of perfluorinated chains to aggregate, even at very low surface density, forming highly organized 2D structures. We believe these findings are important to fully understand related phenomena, such as the formation of hemi-micelles of semifluorinated alkanes at the surface of water and the 2D segregation in mixed Langmuir films of hydrogenated and fluorinated fatty acids. Full article

(This article belongs to the Special Issue Nanoscale 2D Structure and Self-Assembled Properties)

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21 pages, 6102 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Improved Hardness and Thermal Stability of Nanocrystalline Nickel Electrodeposited with the Addition of Cysteine

by Tamás Kolonits, Zsolt Czigány, László Péter, Imre Bakonyi and Jenő Gubicza

Nanomaterials 2020, 10(11), 2254; https://doi.org/10.3390/nano10112254 - 13 Nov 2020

Cited by 5 | Viewed by 2385

Abstract

Experiments were conducted for the study of the effect of cysteine addition on the microstructure of nanocrystalline Ni films electrodeposited from a nickel sulfate-based bath. Furthermore, the thermal stability of the nanostructure of Ni layers processed with cysteine addition was also investigated. It [...] Read more.

Experiments were conducted for the study of the effect of cysteine addition on the microstructure of nanocrystalline Ni films electrodeposited from a nickel sulfate-based bath. Furthermore, the thermal stability of the nanostructure of Ni layers processed with cysteine addition was also investigated. It was found that with increasing cysteine content in the bath, the grain size decreased, while the dislocation density and the twin fault probability increased. Simultaneously, the hardness increased due to cysteine addition through various effects. Saturation in the microstructure and hardness was achieved at cysteine contents of 0.3–0.4 g/L. Moreover, the texture changed from (220) to (200) with increasing the concentration of cysteine. The hardness of the Ni films processed with the addition of 0.4 g/L cysteine (∼6800 MPa) was higher than the values obtained for other additives in the literature (<6000 MPa). This hardness was further enhanced to ∼8400 MPa when the Ni film was heated up to 500 K. It was revealed that the hardness remained as high as 6000 MPa even after heating up to 750 K, while for other additives, the hardness decreased below 3000 MPa at the same temperature. Full article

(This article belongs to the Special Issue Advances in Micro- and Nanomechanics)

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11 pages, 4575 KiB

Open AccessEditor’s ChoiceArticle

Synthesis of Core–Double Shell Nylon-ZnO/Polypyrrole Electrospun Nanofibers

by Mihaela Beregoi, Nicoleta Preda, Andreea Costas, Monica Enculescu, Raluca Florentina Negrea, Horia Iovu and Ionut Enculescu

Nanomaterials 2020, 10(11), 2241; https://doi.org/10.3390/nano10112241 - 12 Nov 2020

Cited by 8 | Viewed by 2788

Abstract

Core–double shell nylon-ZnO/polypyrrole electrospun nanofibers were fabricated by combining three straightforward methods (electrospinning, sol–gel synthesis and electrodeposition). The hybrid fibrous organic–inorganic nanocomposite was obtained starting from freestanding nylon 6/6 nanofibers obtained through electrospinning. Nylon meshes were functionalized with a very thin, continuous ZnO [...] Read more.

Core–double shell nylon-ZnO/polypyrrole electrospun nanofibers were fabricated by combining three straightforward methods (electrospinning, sol–gel synthesis and electrodeposition). The hybrid fibrous organic–inorganic nanocomposite was obtained starting from freestanding nylon 6/6 nanofibers obtained through electrospinning. Nylon meshes were functionalized with a very thin, continuous ZnO film by a sol–gel process and thermally treated in order to increase its crystallinity. Further, the ZnO coated networks were used as a working electrode for the electrochemical deposition of a very thin, homogenous polypyrrole layer. X-ray diffraction measurements were employed for characterizing the ZnO structures while spectroscopic techniques such as FTIR and Raman were employed for describing the polypyrrole layer. An elemental analysis was performed through X-ray microanalysis, confirming the expected double shell structure. A detailed micromorphological characterization through FESEM and TEM assays evidenced the deposition of both organic and inorganic layers. Highly transparent, flexible due to the presence of the polymer core and embedding a semiconducting heterojunction, such materials can be easily tailored and integrated in functional platforms with a wide range of applications. Full article

(This article belongs to the Special Issue Thin Films Based on Nanocomposites)

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26 pages, 7052 KiB

Open AccessEditor’s ChoiceArticle

Thermodynamic Behaviors of Adsorbed Methane Storage Systems Based on Nanoporous Carbon Adsorbents Prepared from Coconut Shells

by Ilya E. Men’shchikov, Andrey V. Shkolin, Evgeny M. Strizhenov, Elena V. Khozina, Sergey S. Chugaev, Andrey A. Shiryaev, Anatoly A. Fomkin and Anatoly A. Zherdev

Nanomaterials 2020, 10(11), 2243; https://doi.org/10.3390/nano10112243 - 12 Nov 2020

Cited by 22 | Viewed by 3161

Abstract

The present work focused on the experimental study of the performance of a scaled system of adsorbed natural gas (ANG) storage and transportation based on carbon adsorbents. For this purpose, three different samples of activated carbons (AC) were prepared by varying the size [...] Read more.

The present work focused on the experimental study of the performance of a scaled system of adsorbed natural gas (ANG) storage and transportation based on carbon adsorbents. For this purpose, three different samples of activated carbons (AC) were prepared by varying the size of coconut shell char granules and steam activation conditions. The parameters of their porous structure, morphology, and chemical composition were determined from the nitrogen adsorption at 77 K, X-ray diffraction (XRD), small-angle X-ray scattering (SAXS), and scanning electron microscopy (SEM) measurements. The methane adsorption data measured within the temperature range from 178 to 360 K and at pressures up to 25 MPa enabled us to identify the most efficient adsorbent among the studied materials: AC-90S. The differential heats of methane adsorption on AC-90S were determined in order to simulate the gas charge/discharge processes in the ANG system using a mathematical model with consideration for thermal effects. The results of simulating the charge/discharge processes under two different conditions of heat exchange are consistent with the experimentally determined temperature distribution over a scaled ANG storage tank filled with the compacted AC-90S adsorbent and equipped with temperature sensors and heat-exchanger devices. The amounts of methane delivered from the ANG storage system employing AC-90S as an adsorbent differ from the model predictions by 4–6%. Both the experiments and mathematical modeling showed that the thermal regulation of the ANG storage tank ensured the higher rates of charge/discharge processes compared to the thermal insulation. Full article

(This article belongs to the Special Issue Nanostructured Carbons for Environmental and Energy Technologies)

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16 pages, 8106 KiB

Open AccessEditor’s ChoiceArticle

Reduced Graphene Oxide Sheets as Inhibitors of the Photochemical Reactions of α-Lipoic Acid in the Presence of Ag and Au Nanoparticles

by N’ghaya Toulbe, Malvina S. Stroe, Monica Daescu, Radu Cercel, Alin Mogos, Daniela Dragoman, Marcela Socol, Ionel Mercioniu and Mihaela Baibarac

Nanomaterials 2020, 10(11), 2238; https://doi.org/10.3390/nano10112238 - 11 Nov 2020

Cited by 5 | Viewed by 3103

Abstract

The influence of Ag and Au nanoparticles and reduced graphene oxide (RGO) sheets on the photodegradation of α-lipoic acid (ALA) was determined by UV-VIS spectroscopy. The ALA photodegradation was explained by considering the affinity of thiol groups for the metallic nanoparticles synthesized in [...] Read more.

The influence of Ag and Au nanoparticles and reduced graphene oxide (RGO) sheets on the photodegradation of α-lipoic acid (ALA) was determined by UV-VIS spectroscopy. The ALA photodegradation was explained by considering the affinity of thiol groups for the metallic nanoparticles synthesized in the presence of trisodium citrate. The presence of excipients did not induce further changes when ALA interacts with Ag and Au nanoparticles with sizes of 5 and 10 nm by exposure to UV light. Compared to the Raman spectrum of ALA powder, changes in Raman lines’ position and relative intensities when ALA has interacted with films obtained from Au nanoparticles with sizes between 5 and 50 nm were significant. These changes were explained by considering the chemical mechanism of surface-enhanced Raman scattering (SERS) spectroscopy. The photodegradation of ALA that had interacted with metallic nanoparticles was inhibited in the presence of RGO sheets. Full article

(This article belongs to the Special Issue Properties and Applications of Graphene and Its Derivatives)

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15 pages, 3089 KiB

Open AccessEditor’s ChoiceArticle

Femtosecond Double-Pulse Laser Ablation and Deposition of Co-Doped ZnS Thin Films

by Ignacio Lopez-Quintas, Esther Rebollar, David Ávila-Brande, Jesús G. Izquierdo, Luis Bañares, Carlos Díaz-Guerra, Ana Urbieta, Marta Castillejo, Rebeca de Nalda and Margarita Martín

Nanomaterials 2020, 10(11), 2229; https://doi.org/10.3390/nano10112229 - 10 Nov 2020

Cited by 11 | Viewed by 2887

Abstract

Nanostructured thin films of Co-doped zinc sulfide were synthesized through femtosecond pulsed laser deposition. The scheme involved ablation of physically mixed Co and ZnS with pairs of ultrashort pulses separated in time in the 0–300 ps range. In situ monitorization of the deposition [...] Read more.

Nanostructured thin films of Co-doped zinc sulfide were synthesized through femtosecond pulsed laser deposition. The scheme involved ablation of physically mixed Co and ZnS with pairs of ultrashort pulses separated in time in the 0–300 ps range. In situ monitorization of the deposition process was carried out through a simultaneous reflectivity measurement. The crystallinity of generated nanoparticles and the inclusion of Co in the ZnS lattice is demonstrated by transmission electron microscopy and energy dispersive X-ray microanalysis (TEM-EDX) characterization. Surface morphology, Raman response, and photoluminescence of the films have also been assessed. The role of interpulse temporal separation is most visible in the thickness of the films obtained at the same total fluence, with much thicker films deposited with short delays than with individual uncoupled pulses. The proportion of Co in the synthesized doped ZnS nanoparticles is found to be substantially lower than the original proportion, and practically independent on interpulse delay. Full article

(This article belongs to the Special Issue Laser Synthesis and Modification of Materials at the Nanoscale)

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10 pages, 3798 KiB

Open AccessEditor’s ChoiceArticle

Highly Conductive PEDOT:PSS Thin Films with Two-Dimensional Lamellar Stacked Multi-Layers

by Youngno Kim, Yunryeol Kim and Jung Hyun Kim

Nanomaterials 2020, 10(11), 2211; https://doi.org/10.3390/nano10112211 - 6 Nov 2020

Cited by 31 | Viewed by 6128

Abstract

Conjugated polymers are desired as organic electrode materials because of their functional properties such as solution process, low cost, and transparency. Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), in particular, shows the highest applicability, but its heterogeneous structure presents limitations in terms of electrical conductivity. In this study, [...] Read more.

Conjugated polymers are desired as organic electrode materials because of their functional properties such as solution process, low cost, and transparency. Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), in particular, shows the highest applicability, but its heterogeneous structure presents limitations in terms of electrical conductivity. In this study, a facile method to fabricate multi-layered thin films with higher ordered structures was developed. Through the etching process with H₂SO₄ and dimethyl sulfoxide(DMSO), the insulated rich-PSS was removed from the upper layer to improve its electrical properties and rearrange the PEDOT molecular structures. The thickness of PEDOT:PSS thin films was experimentally optimized to maximize the enhancement of carrier mobility via a layer-by-layer (LBL) process. The combined method, consisted of etching and the LBL process, showed the improvement of the charge carrier mobility from 0.62 to 2.80 cm² V⁻¹ s⁻¹. The morphology and crystallinity of the ordered PEDOT:PSS structure were investigated by X-ray photoemission spectroscopy (XPS), Raman, and X-ray diffraction (XRD). As a result, two-dimensional lamellar-stacked PEDOT:PSS thin films were fabricated through the repetitive etching and LBL process. The optimized PEDOT:PSS thin film showed an excellent electrical conductivity of 3026 S cm⁻¹, which is 3.8 times higher than that of the pristine film (801 S cm⁻¹). Full article

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16 pages, 28691 KiB

Open AccessEditor’s ChoiceArticle

On the Formation of Black Silicon Features by Plasma-Less Etching of Silicon in Molecular Fluorine Gas

by Bishal Kafle, Ahmed Ismail Ridoy, Eleni Miethig, Laurent Clochard, Edward Duffy, Marc Hofmann and Jochen Rentsch

Nanomaterials 2020, 10(11), 2214; https://doi.org/10.3390/nano10112214 - 6 Nov 2020

Cited by 11 | Viewed by 3192

Abstract

In this paper, we study the plasma-less etching of crystalline silicon (c-Si) by F₂/N₂ gas mixture at moderately elevated temperatures. The etching is performed in an inline etching tool, which is specifically developed to lower costs for products needing a [...] Read more.

In this paper, we study the plasma-less etching of crystalline silicon (c-Si) by F₂/N₂ gas mixture at moderately elevated temperatures. The etching is performed in an inline etching tool, which is specifically developed to lower costs for products needing a high volume manufacturing etching platform such as silicon photovoltaics. Specifically, the current study focuses on developing an effective front-side texturing process on Si(100) wafers. Statistical variation of the tool parameters is performed to achieve high etching rates and low surface reflection of the textured silicon surface. It is observed that the rate and anisotropy of the etching process are strongly defined by the interaction effects between process parameters such as substrate temperature, F₂ concentration, and process duration. The etching forms features of sub-micron dimensions on c-Si surface. By maintaining the anisotropic nature of etching, weighted surface reflection (R_w) as low as R_w < 2% in Si(100) is achievable. The lowering of R_w is mainly due to the formation of deep, density grade nanostructures, so-called black silicon, with lateral dimensions that are smaller to the major wavelength ranges of interest in silicon photovoltaics. Full article

(This article belongs to the Special Issue Nanostructured Materials for Energy Storage and Conversion)

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20 pages, 3990 KiB

Open AccessEditor’s ChoiceArticle

Structural Study of (Hydroxypropyl)Methyl Cellulose Microemulsion-Based Gels Used for Biocompatible Encapsulations

by Evdokia Vassiliadi, Evgenia Mitsou, Spyridon Avramiotis, Christos L. Chochos, Franz Pirolt, Martin Medebach, Otto Glatter, Aristotelis Xenakis and Maria Zoumpanioti

Nanomaterials 2020, 10(11), 2204; https://doi.org/10.3390/nano10112204 - 5 Nov 2020

Cited by 8 | Viewed by 2603

Abstract

(Hydroxypropyl)methyl cellulose (HPMC) can be used to form gels integrating a w/o microemulsion. The formulation in which a microemulsion is mixed with a hydrated HPMC matrix has been successfully used as a carrier of biocompatible ingredients. However, little is known about the structure [...] Read more.

(Hydroxypropyl)methyl cellulose (HPMC) can be used to form gels integrating a w/o microemulsion. The formulation in which a microemulsion is mixed with a hydrated HPMC matrix has been successfully used as a carrier of biocompatible ingredients. However, little is known about the structure of these systems. To elucidate this, scanning electron microscopy was used to examine the morphology and the bulk of the microemulsion-based gels (MBGs) and small-angle X-ray scattering to clarify the structure and detect any residual reverse micelles after microemulsion incorporation in the gel. Electron paramagnetic resonance spectroscopy was applied using spin probes to investigate the polar and non-polar areas of the gel. Furthermore, the enzyme-labelling technique was followed to investigate the location of an enzyme in the matrix. A structural model for HPMC matrix is proposed according to which, although a w/o microemulsion is essential to form the final gel, no microemulsion droplets can be detected after incorporation in the gel. Channels are formed by the organic solvent (oil), which are coated by surfactant molecules and a water layer in which the enzyme can be hosted. Full article

(This article belongs to the Section Biology and Medicines)

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18 pages, 10404 KiB

Open AccessEditor’s ChoiceArticle

Molecular Dynamics Studies of Poly(Lactic Acid) Nanoparticles and Their Interactions with Vitamin E and TLR Agonists Pam₁CSK₄ and Pam₃CSK₄

by Simon Megy, Stephanie Aguero, David Da Costa, Myriam Lamrayah, Morgane Berthet, Charlotte Primard, Bernard Verrier and Raphael Terreux

Nanomaterials 2020, 10(11), 2209; https://doi.org/10.3390/nano10112209 - 5 Nov 2020

Cited by 10 | Viewed by 3968

Abstract

Poly(lactic acid) (PLA) nanoparticles (NPs) are widely investigated due to their bioresorbable, biocompatible and low immunogen properties. Interestingly, many recent studies show that they can be efficiently used as drug delivery systems or as adjuvants to enhance vaccine efficacy. Our work focuses on [...] Read more.

Poly(lactic acid) (PLA) nanoparticles (NPs) are widely investigated due to their bioresorbable, biocompatible and low immunogen properties. Interestingly, many recent studies show that they can be efficiently used as drug delivery systems or as adjuvants to enhance vaccine efficacy. Our work focuses on the molecular mechanisms involved during the nanoprecipitation of PLA NPs from concentrated solutions of lactic acid polymeric chains, and their specific interactions with biologically relevant molecules. In this study, we evaluated the ability of a PLA-based nanoparticle drug carrier to vectorize either vitamin E or the Toll-like receptor (TLR) agonists Pam₁CSK₄ and Pam₃CSK₄, which are potent activators of the proinflammatory transcription factor NF-κB. We used dissipative particle dynamics (DPD) to simulate large systems mimicking the nanoprecipitation process for a complete NP. Our results evidenced that after the NP formation, Pam₁CSK₄ and Pam₃CSK₄ molecules end up located on the surface of the particle, interacting with the PLA chains via their fatty acid chains, whereas vitamin E molecules are buried deeper in the core of the particle. Our results allow for a better understanding of the molecular mechanisms responsible for the formation of the PLA NPs and their interactions with biological molecules located either on their surfaces or encapsulated within them. This work should allow for a rapid development of better biodegradable and safe vectorization systems with new drugs in the near future. Full article

(This article belongs to the Special Issue Computational Modeling and Simulation for Nanomaterials, Nanotechnology, and Nanoscience)

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16 pages, 5798 KiB

Open AccessEditor’s ChoiceArticle

Effect of DNA Origami Nanostructures on hIAPP Aggregation

by Marcel Hanke, Alejandro Gonzalez Orive, Guido Grundmeier and Adrian Keller

Nanomaterials 2020, 10(11), 2200; https://doi.org/10.3390/nano10112200 - 4 Nov 2020

Cited by 9 | Viewed by 4211

Abstract

The aggregation of human islet amyloid polypeptide (hIAPP) plays a major role in the pathogenesis of type 2 diabetes mellitus (T2DM), and numerous strategies for controlling hIAPP aggregation have been investigated so far. In particular, several organic and inorganic nanoparticles (NPs) have shown [...] Read more.

The aggregation of human islet amyloid polypeptide (hIAPP) plays a major role in the pathogenesis of type 2 diabetes mellitus (T2DM), and numerous strategies for controlling hIAPP aggregation have been investigated so far. In particular, several organic and inorganic nanoparticles (NPs) have shown the potential to influence the aggregation of hIAPP and other amyloidogenic proteins and peptides. In addition to conventional NPs, DNA nanostructures are receiving more and more attention from the biomedical field. Therefore, in this work, we investigated the effects of two different DNA origami nanostructures on hIAPP aggregation. To this end, we employed in situ turbidity measurements and ex situ atomic force microscopy (AFM). The turbidity measurements revealed a retarding effect of the DNA nanostructures on hIAPP aggregation, while the AFM results showed the co-aggregation of hIAPP with the DNA origami nanostructures into hybrid peptide–DNA aggregates. We assume that this was caused by strong electrostatic interactions between the negatively charged DNA origami nanostructures and the positively charged peptide. Most intriguingly, the influence of the DNA origami nanostructures on hIAPP aggregation differed from that of genomic double-stranded DNA (dsDNA) and appeared to depend on DNA origami superstructure. DNA origami nanostructures may thus represent a novel route for modulating amyloid aggregation in vivo. Full article

(This article belongs to the Special Issue The Application of DNA Nanotechnology)

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16 pages, 2633 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Empirical Modelling of Hydrodynamic Effects on Starch Nanoparticles Precipitation in a Spinning Disc Reactor

by Sahr Sana, Vladimir Zivkovic and Kamelia Boodhoo

Nanomaterials 2020, 10(11), 2202; https://doi.org/10.3390/nano10112202 - 4 Nov 2020

Cited by 8 | Viewed by 3345

Abstract

Empirical correlations have been developed to relate experimentally determined starch nanoparticle size obtained in a solvent–antisolvent precipitation process with key hydrodynamic parameters of a spinning disc reactor (SDR). Three different combinations of dimensionless groups including a conventional Reynolds number (Re), rotational [...] Read more.

Empirical correlations have been developed to relate experimentally determined starch nanoparticle size obtained in a solvent–antisolvent precipitation process with key hydrodynamic parameters of a spinning disc reactor (SDR). Three different combinations of dimensionless groups including a conventional Reynolds number (Re), rotational Reynolds number (Re_ω) and Rossby number (Ro) have been applied in individual models for two disc surfaces (smooth and grooved) to represent operating variables affecting film flow such as liquid flowrate and disc rotational speed, whilst initial supersaturation (S) has been included to represent varying antisolvent concentrations. Model 1 featuring a combination of Re, Re_ω and S shows good agreement with the experimental data for both the grooved and smooth discs. For the grooved disc, Re has a greater impact on particle size, whereas Re_ω is more influential on the smooth disc surface, the difference likely being due to the passive mixing induced by the grooves irrespective of the magnitude of the disc speed. Supersaturation has little impact on particle size within the limited initial supersaturation range studied. Model 2 which characterises both flow rate and disc rotational speed through Ro alone and combined with Re was less accurate in predicting particle size due to several inherent limitations. Full article

(This article belongs to the Special Issue Process Intensification Techniques for the Production of Nanoparticles)

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13 pages, 1447 KiB

Open AccessEditor’s ChoiceArticle

Surface Enhanced Raman Scattering on Regular Arrays of Gold Nanostructures: Impact of Long-Range Interactions and the Surrounding Medium

by Iman Ragheb, Macilia Braïk, Stéphanie Lau-Truong, Abderrahmane Belkhir, Anna Rumyantseva, Sergei Kostcheev, Pierre-Michel Adam, Alexandre Chevillot-Biraud, Georges Lévi, Jean Aubard, Leïla Boubekeur-Lecaque and Nordin Félidj

Nanomaterials 2020, 10(11), 2201; https://doi.org/10.3390/nano10112201 - 4 Nov 2020

Cited by 11 | Viewed by 2768

Abstract

Long-range interaction in regular metallic nanostructure arrays can provide the possibility to manipulate their optical properties, governed by the excitation of localized surface plasmon (LSP) resonances. When assembling the nanoparticles in an array, interactions between nanoparticles can result in a strong electromagnetic coupling [...] Read more.

Long-range interaction in regular metallic nanostructure arrays can provide the possibility to manipulate their optical properties, governed by the excitation of localized surface plasmon (LSP) resonances. When assembling the nanoparticles in an array, interactions between nanoparticles can result in a strong electromagnetic coupling for specific grating constants. Such a grating effect leads to narrow LSP peaks due to the emergence of new radiative orders in the plane of the substrate, and thus, an important improvement of the intensity of the local electric field. In this work, we report on the optical study of LSP modes supported by square arrays of gold nanodiscs deposited on an indium tin oxyde (ITO) coated glass substrate, and its impact on the surface enhanced Raman scattering (SERS) of a molecular adsorbate, the mercapto benzoic acid (4-MBA). We estimated the Raman gain of these molecules, by varying the grating constant and the refractive index of the surrounding medium of the superstrate, from an asymmetric medium (air) to a symmetric one (oil). We show that the Raman gain can be improved with one order of magnitude in a symmetric medium compared to SERS experiments in air, by considering the appropriate grating constant. Our experimental results are supported by FDTD calculations, and confirm the importance of the grating effect in the design of SERS substrates. Full article

(This article belongs to the Special Issue Application of Novel Plasmonic Nanomaterials on SERS)

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16 pages, 4204 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Capsules Rheology in Carreau–Yasuda Fluids

by Alessandro Coclite, Giuseppe Maria Coclite and Domenico De Tommasi

Nanomaterials 2020, 10(11), 2190; https://doi.org/10.3390/nano10112190 - 3 Nov 2020

Cited by 6 | Viewed by 2905

Abstract

In this paper, a Multi Relaxation Time Lattice Boltzmann scheme is used to describe the evolution of a non-Newtonian fluid. Such method is coupled with an Immersed-Boundary technique for the transport of arbitrarily shaped objects navigating the flow. The no-slip boundary conditions on [...] Read more.

In this paper, a Multi Relaxation Time Lattice Boltzmann scheme is used to describe the evolution of a non-Newtonian fluid. Such method is coupled with an Immersed-Boundary technique for the transport of arbitrarily shaped objects navigating the flow. The no-slip boundary conditions on immersed bodies are imposed through a convenient forcing term accounting for the hydrodynamic force generated by the presence of immersed geometries added to momentum equation. Moreover, such forcing term accounts also for the force induced by the shear-dependent viscosity model characterizing the non-Newtonian behavior of the considered fluid. Firstly, the present model is validated against well-known benchmarks, namely the parabolic velocity profile obtained for the flow within two infinite laminae for five values of the viscosity model exponent, n = 0.25, 0.50, 0.75, 1.0, and 1.5. Then, the flow within a squared lid-driven cavity for Re = 1000 and 5000 (being Re the Reynolds number) is computed as a function of n for a shear-thinning (n < 1) fluid. Indeed, the local decrements in the viscosity field achieved in high-shear zones implies the increment in the local Reynolds number, thus moving the position of near-walls minima towards lateral walls. Moreover, the revolution under shear of neutrally buoyant plain elliptical capsules with different Aspect Ratio (AR = 2 and 3) is analyzed for shear-thinning (n < 1), Newtonian (n = 1), and shear-thickening (n > 1) surrounding fluids. Interestingly, the power law by Huang et al. describing the revolution period of such capsules as a function of the Reynolds number and the existence of a critical value, Re

_{c}

, after which the tumbling is inhibited in confirmed also for non-Newtonian fluids. Analogously, the equilibrium lateral position

y_{e q}

of such neutrally buoyant capsules when transported in a plane-Couette flow is studied detailing the variation of

y_{e q}

as a function of the Reynolds number as well as of the exponent n. Full article

(This article belongs to the Special Issue Multiscale Innovative Materials and Structures)

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14 pages, 41918 KiB

Open AccessEditor’s ChoiceArticle

Influence of Nanotopography on Early Bone Healing during Controlled Implant Loading

by Renan de Barros e Lima Bueno, Katia J. Ponce, Ana Paula Dias, Dainelys Guadarrama Bello, John B. Brunski and Antonio Nanci

Nanomaterials 2020, 10(11), 2191; https://doi.org/10.3390/nano10112191 - 3 Nov 2020

Cited by 8 | Viewed by 2269

Abstract

Nanoscale surface modifications influence peri-implant cell fate decisions and implant loading generates local tissue deformation, both of which will invariably impact bone healing. The objective of this study is to determine how loading affects healing around implants with nanotopography. Implants with a nanoporous [...] Read more.

Nanoscale surface modifications influence peri-implant cell fate decisions and implant loading generates local tissue deformation, both of which will invariably impact bone healing. The objective of this study is to determine how loading affects healing around implants with nanotopography. Implants with a nanoporous surface were placed in over-sized osteotomies in rat tibiae and held stable by a system that permits controlled loading. Three regimens were applied: (a) no loading, (b) one daily loading session with a force of 1.5N, and (c) two such daily sessions. At 7 days post implantation, animals were sacrificed for histomorphometric and DNA microarray analyses. Implants subjected to no loading or only one daily loading session achieved high bone-implant contact (BIC), bone-implant distance (BID) and bone formation area near the implant (BFAt) values, while those subjected to two daily loading sessions showed less BFAt and BIC and more BID. Gene expression profiles differed between all groups mainly in unidentified genes, and no modulation of genes associated with inflammatory pathways was detected. These results indicate that implants with nanotopography can achieve a high level of bone formation even under micromotion and limit the inflammatory response to the implant surface. Full article

(This article belongs to the Special Issue Nanostructured Materials for Biomedicine and Bioengineering)

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27 pages, 6075 KiB

Open AccessEditor’s ChoiceArticle

Magnetotransport Properties of Ferromagnetic Nanoparticles in a Semiconductor Matrix Studied by Precise Size-Selective Cluster Ion Beam Deposition

by Nicolas Gack, Gleb Iankevich, Cahit Benel, Robert Kruk, Di Wang, Horst Hahn and Thomas Reisinger

Nanomaterials 2020, 10(11), 2192; https://doi.org/10.3390/nano10112192 - 3 Nov 2020

Cited by 7 | Viewed by 2550

Abstract

The combination of magnetic and semiconducting properties in one material system has great potential for integration of emerging spintronics with conventional semiconductor technology. One standard route for the synthesis of magnetic semiconductors is doping of semiconductors with magnetic atoms. In many semiconductor–magnetic–dopant systems, [...] Read more.

The combination of magnetic and semiconducting properties in one material system has great potential for integration of emerging spintronics with conventional semiconductor technology. One standard route for the synthesis of magnetic semiconductors is doping of semiconductors with magnetic atoms. In many semiconductor–magnetic–dopant systems, the magnetic atoms form precipitates within the semiconducting matrix. An alternative and controlled way to realize such nanocomposite materials is the assembly by co-deposition of size-selected cluster ions and a semiconductor. Here we follow the latter approach to demonstrate that this fabrication route can be used to independently study the influence of cluster concentration and cluster size on magneto-transport properties. In this case we study Fe clusters composed of approximately 500 or 1000 atoms soft-landed into a thermally evaporated amorphous Ge matrix. The analysis of field and temperature dependent transport shows that tunneling processes affected by Coulomb blockade dominate at low temperatures. The nanocomposites show saturating tunneling magnetoresistance, additionally superimposed by at least one other effect not saturating upon the maximum applied field of 6 T. The nanocomposites’ resistivity and the observed tunneling magnetoresistance depend exponentially on the average distance between cluster surfaces. On the contrary, there is no notable influence of the cluster size on the tunneling magnetoresistance. Full article

(This article belongs to the Section Nanocomposite Materials)

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