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Nanomaterials
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Computational Modeling and Simulation for Nanomaterials, Nanotechnology, and Nanoscience
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Computational Modeling and Simulation for Nanomaterials, Nanotechnology, and Nanoscience

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Theory and Simulation of Nanostructures".

Deadline for manuscript submissions: closed (18 October 2020) | Viewed by 74436

Special Issue Editor

Prof. Dr. Giovanni Formica

E-Mail Website
Guest Editor
Department of Architecture, University of “Roma Tre”, Rome, Italy
Interests: nonlinear dynamics and stability; carbon nanotube composites; multi-scale, computational mechanics and multiphysics; non-standard finite element formulation and implementation; advanced numerical solvers for nonlinear problems; meta-heuristic algorithms for optimization
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Special Issue Information

Dear Colleagues,

Nanoscience and nanotechnology emerged in the last decades at the forefront of a wide array of research fields, due to the highly challenging and surprising properties of nanomaterials and nanosystems. These properties allow nanomaterials in different forms (0D, 1D, 2D, 3D) and phases or nanosystems to be utilised in a wealth of applications, ranging from biomedical to industrial engineering. Moreover, these materials often become themselves an interdisciplinary bridge between different scientific and technological domains.

When accounting for the effects of various phenomena occurring at the nanoscale, models and simulations together tend to reveal unsolved issues while enabling formidable advances that push forward the rich spectrum of technologies based on nanostructured materials. Moreover, it is clear that, for such materials, theoretical formulations and numerical solvers, dealing with mesoscopic or macroscopic descriptions, are necessary tools to enhance experiments and practical investigations.

This Special Issue aims to gather the rich variety of recent research breakthroughs in the perspective described above, and it aims to cover recent advances in the study of phenomena, the manipulation of materials at different scales, the design and characterization of nanoapplications, all enabled by computational modeling and simulation of nanomaterials.

Prof. Dr. Giovanni Formica
Guest Editor

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Keywords

  • physical nanomaterial models for experimental design and characterization
  • mesoscopic/macroscopic formulations
  • multi-scale computational approaches
  • coupled, multi-physics problems
  • carbon nanotube nanocomposites

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Published Papers (17 papers)

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20 pages, 1185 KiB  
Article
Torsional Characteristics of Carbon Nanotubes: Micropolar Elasticity Models and Molecular Dynamics Simulation
by Razie Izadi, Meral Tuna, Patrizia Trovalusci and Esmaeal Ghavanloo
Nanomaterials 2021, 11(2), 453; https://doi.org/10.3390/nano11020453 - 11 Feb 2021
Cited by 30 | Viewed by 2607
Abstract
Efficient application of carbon nanotubes (CNTs) in nano-devices and nano-materials requires comprehensive understanding of their mechanical properties. As observations suggest size dependent behaviour, non-classical theories preserving the memory of body’s internal structure via additional material parameters offer great potential when a continuum modelling [...] Read more.
Efficient application of carbon nanotubes (CNTs) in nano-devices and nano-materials requires comprehensive understanding of their mechanical properties. As observations suggest size dependent behaviour, non-classical theories preserving the memory of body’s internal structure via additional material parameters offer great potential when a continuum modelling is to be preferred. In the present study, micropolar theory of elasticity is adopted due to its peculiar character allowing for incorporation of scale effects through additional kinematic descriptors and work-conjugated stress measures. An optimisation approach is presented to provide unified material parameters for two specific class of single-walled carbon nanotubes (e.g., armchair and zigzag) by minimizing the difference between the apparent shear modulus obtained from molecular dynamics (MD) simulation and micropolar beam model considering both solid and tubular cross-sections. The results clearly reveal that micropolar theory is more suitable compared to internally constraint couple stress theory, due to the essentiality of having skew-symmetric stress and strain measures, as well as to the classical local theory (Cauchy of Grade 1), which cannot accounts for scale effects. To the best of authors’ knowledge, this is the first time that unified material parameters of CNTs are derived through a combined MD-micropolar continuum theory. Full article
(This article belongs to the Special Issue Computational Modeling and Simulation for Nanomaterials, Nanotechnology, and Nanoscience)
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22 pages, 6456 KiB  
Article
Experimental and Theoretical Studies on Sustainable Synthesis of Gold Sol Displaying Dichroic Effect
by Anshuman Jakhmola, Raffaele Vecchione, Valentina Onesto, Francesco Gentile, Maurizio Celentano and Paolo Antonio Netti
Nanomaterials 2021, 11(1), 236; https://doi.org/10.3390/nano11010236 - 18 Jan 2021
Cited by 19 | Viewed by 3775
Abstract
Gold nanoparticles depending on their shape and mixtures of multiple shapes can exhibit peculiar optical properties, including the dichroic effect typical of the Lycurgus cup, which has puzzled scientists for a long time. Such optical properties have been recently exploited in several fields [...] Read more.
Gold nanoparticles depending on their shape and mixtures of multiple shapes can exhibit peculiar optical properties, including the dichroic effect typical of the Lycurgus cup, which has puzzled scientists for a long time. Such optical properties have been recently exploited in several fields such as paint technology, sensors, dichroic polarizers, display (LCD) devices, laser applications, solar cells and photothermal therapy among others. In this article, we have demonstrated a simple room temperature one-pot synthesis of gold sol displaying a dichroic effect using a slow reduction protocol involving only trisodium citrate as a reducing agent. We found that the dichroic gold sol can be easily formed at room temperature by reducing gold salt by trisodium citrate below a certain critical concentration. The sol displayed an orangish-brown color in scattered/reflected light and violet/blue/indigo/purple/red/pink in transmitted light, depending on the experimental conditions. With minor changes such as the introduction of a third molecule or replacing a small amount of water in the reaction mixture with ethanol, the color of the gold sol under transmitted light changed and a variety of shades of red, pink, cobalt blue, violet, magenta and purple were obtained. The main advantage of the proposed method lies in its simplicity, which involves the identification of the right ratio of the reactants, and simple mixing of reactants at room temperature with no other requirements. TEM micrographs displayed the formation of two main types of particles viz. single crystal gold nanoplates and polycrystalline faceted polyhedron nanoparticles. The mechanism of growth of the nanoplates and faceted polyhedron particles have been described by an enhanced diffusion limited aggregation numerical scheme, where it was assumed that both trisodium citrate and the gold ions in solution undergo a stochastic Brownian motion, and that the evolution of the entire system is regulated by a principle of energy minimization. The predictions of the model matched with the experiments with a good accuracy, indicating that the initial hypothesis is correct. Full article
(This article belongs to the Special Issue Computational Modeling and Simulation for Nanomaterials, Nanotechnology, and Nanoscience)
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24 pages, 3142 KiB  
Article
Optimal Design of CNT-Nanocomposite Nonlinear Shells
by Leonardo Leonetti, Giovanni Garcea, Domenico Magisano, Francesco Liguori, Giovanni Formica and Walter Lacarbonara
Nanomaterials 2020, 10(12), 2484; https://doi.org/10.3390/nano10122484 - 10 Dec 2020
Cited by 13 | Viewed by 2685
Abstract
Carbon nanotube/polymer nanocomposite plate- and shell-like structures will be the next generation lightweight structures in advanced applications due to the superior multifunctional properties combined with lightness. Here material optimization of carbon nanotube/polymer nanocomposite beams and shells is tackled via ad hoc nonlinear finite [...] Read more.
Carbon nanotube/polymer nanocomposite plate- and shell-like structures will be the next generation lightweight structures in advanced applications due to the superior multifunctional properties combined with lightness. Here material optimization of carbon nanotube/polymer nanocomposite beams and shells is tackled via ad hoc nonlinear finite element schemes so as to control the loss of stability and overall nonlinear response. Three types of optimizations are considered: variable through-the-thickness volume fraction of random carbon nanotubes (CNTs) distributions, variable volume fraction of randomly oriented CNTs within the mid-surface, aligned CNTs with variable orientation with respect to the mid-surface. The collapse load, which includes both limit points and deformation thresholds, is chosen as the objective/cost function. An efficient computation of the cost function is carried out using the Koiter reduced order model obtained starting from an isogeometric solid-shell model to accurately describe the point-wise material distribution. The sensitivity to geometrical imperfections is also investigated. The optimization is carried out making use of the Global Convergent Method of Moving Asymptotes. The extensive numerical analyses show that varying the volume fraction distribution as well as the CNTs orientation can lead to significantly enhanced performances towards the loss of elastic stability making these lightweight structures more stable. The most striking result is that for curved shells, the unstable postbuckling response of the baseline material can be turned into a globally stable response maintaining the same amount of nanostructural reinforcement but simply tailoring strategically its distribution. Full article
(This article belongs to the Special Issue Computational Modeling and Simulation for Nanomaterials, Nanotechnology, and Nanoscience)
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20 pages, 17084 KiB  
Article
Anisotropic Characterizations of Electrospun PAN Nanofiber Mats Using Design of Experiments
by Blesson Isaac, Robert M. Taylor and Kenneth Reifsnider
Nanomaterials 2020, 10(11), 2273; https://doi.org/10.3390/nano10112273 - 17 Nov 2020
Cited by 10 | Viewed by 3072
Abstract
This paper deals with the dielectric and mechanical characterizations of polyacrylonitrile (PAN)-aligned electrospun nanofiber mats. A two factor three level full factorial experiment is conducted to understand the effect of various parameters on dielectric and mechanical responses. These responses are recorded against randomly [...] Read more.
This paper deals with the dielectric and mechanical characterizations of polyacrylonitrile (PAN)-aligned electrospun nanofiber mats. A two factor three level full factorial experiment is conducted to understand the effect of various parameters on dielectric and mechanical responses. These responses are recorded against randomly oriented and aligned nanofiber mats. Improved properties of electrospun mats have applications in the field of energy storage and nanocomposite reinforcement. Dielectric and mechanical characterizations of PAN mats are vital, as the aligned electrospun mats were found to be useful in advanced energy and mechanical reinforcement applications. Therefore, it is paramount to understand the effects of system parameters to these properties. The design of experiment (DoE) includes two factors and three level full factorial experiments with concentrations of PAN solutions at 8 wt.%, 9 wt.%, and 10 wt.%, and speed of the rotating mandrel (collector) at 3 volt (V), 4 V, and 5 V inputs. The electric field intensity used in the experiment is 1 kV/cm. DoE is conducted to understand the nonlinear interactions of parameters to these responses. The dielectric and mechanical characterizations of 8 wt.%, 9 wt.%, and 10 wt.% with different speeds for the original and improved systems are discussed. It was observed that at 9 wt.% and at all mandrel speeds, the dielectric and tensile properties are optimum. Full article
(This article belongs to the Special Issue Computational Modeling and Simulation for Nanomaterials, Nanotechnology, and Nanoscience)
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18 pages, 10404 KiB  
Article
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 4018
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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15 pages, 2908 KiB  
Article
Three-Step Description of Single-Pulse Formation of Laser-Induced Periodic Surface Structures on Metals
by Evgeny L. Gurevich, Yoann Levy and Nadezhda M. Bulgakova
Nanomaterials 2020, 10(9), 1836; https://doi.org/10.3390/nano10091836 - 14 Sep 2020
Cited by 27 | Viewed by 3728
Abstract
Two different scenarios are usually invoked in the formation of femtosecond Laser-Induced Periodic Surface Structures (LIPSS), either “self-organization” mechanisms or a purely “plasmonic” approach. In this paper, a three-step model of formation of single-laser-shot LIPSS is summarized. It is based on the periodic [...] Read more.
Two different scenarios are usually invoked in the formation of femtosecond Laser-Induced Periodic Surface Structures (LIPSS), either “self-organization” mechanisms or a purely “plasmonic” approach. In this paper, a three-step model of formation of single-laser-shot LIPSS is summarized. It is based on the periodic perturbation of the electronic temperature followed by an amplification, for given spatial periods, of the modulation in the lattice temperature and a final possible relocation by hydrodynamic instabilities. An analytical theory of the evolution of the temperature inhomogeneities is reported and supported by numerical calculations on the examples of three different metals: Al, Au, and Mo. The criteria of the possibility of hydrodynamic instabilities are also discussed. Full article
(This article belongs to the Special Issue Computational Modeling and Simulation for Nanomaterials, Nanotechnology, and Nanoscience)
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20 pages, 2969 KiB  
Article
Comparing Methods for Calculating Nano Crystal Size of Natural Hydroxyapatite Using X-Ray Diffraction
by Marzieh Rabiei, Arvydas Palevicius, Ahmad Monshi, Sohrab Nasiri, Andrius Vilkauskas and Giedrius Janusas
Nanomaterials 2020, 10(9), 1627; https://doi.org/10.3390/nano10091627 - 19 Aug 2020
Cited by 289 | Viewed by 8971
Abstract
We report on a comparison of methods based on XRD patterns for calculating crystal size. In this case, XRD peaks were extracted from hydroxyapatite obtained from cow, pig, and chicken bones. Hydroxyapatite was synthesized through the thermal treatment of natural bones at 950 [...] Read more.
We report on a comparison of methods based on XRD patterns for calculating crystal size. In this case, XRD peaks were extracted from hydroxyapatite obtained from cow, pig, and chicken bones. Hydroxyapatite was synthesized through the thermal treatment of natural bones at 950 °C. XRD patterns were selected by adjustment of X-Pert software for each method and for calculating the size of the crystals. Methods consisted of Scherrer (three models), Monshi–Scherrer, three models of Williamson–Hall (namely the Uniform Deformation Model (UDM), the Uniform Stress Deformation Model (USDM), and the Uniform Deformation Energy Density Model (UDEDM)), Halder–Wanger (H-W), and the Size Strain Plot Method (SSP). These methods have been used and compared together. The sizes of crystallites obtained by the XRD patterns in each method for hydroxyapatite from cow, pig, and chicken were 1371, 457, and 196 nm in the Scherrer method when considering all of the available peaks together (straight line model). A new model (straight line passing the origin) gave 60, 60, and 53 nm, which shows much improvement. The average model gave 56, 58, and 52 nm, for each of the three approaches, respectively, for cow, pig, and chicken. The Monshi–Scherrer method gave 60, 60, and 57 nm. Values of 56, 62, and 65 nm were given by the UDM method. The values calculated by the USDM method were 60, 62, and 62 nm. The values of 62, 62, and 65 nm were given by the UDEDM method for cow, pig, and chicken, respectively. Furthermore, the crystal size value was 4 nm for all samples in the H-W method. Values were also calculated as 43, 62, and 57 nm in the SSP method for cow, pig, and chicken tandemly. According to the comparison of values in each method, the Scherrer method (straight line model) for considering all peaks led to unreasonable values. Nevertheless, other values were in the acceptable range, similar to the reported values in the literature. Experimental analyses, such as specific surface area by gas adsorption (Brunauer–Emmett–Teller (BET)) and Transmission Electron Microscopy (TEM), were utilized. In the final comparison, parameters of accuracy, ease of calculations, having a check point for the researcher, and difference between the obtained values and experimental analysis by BET and TEM were considered. The Monshi–Scherrer method provided ease of calculation and a decrease in errors by applying least squares to the linear plot. There is a check point for this line that the slope must not be far from one. Then, the intercept gives the most accurate crystal size. In this study, the setup of values for BET (56, 52, and 49 nm) was also similar to the Monshi–Scherrer method and the use of it in research studies of nanotechnology is advised. Full article
(This article belongs to the Special Issue Computational Modeling and Simulation for Nanomaterials, Nanotechnology, and Nanoscience)
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24 pages, 7400 KiB  
Article
A Comparison of Empirical Correlations of Viscosity and Thermal Conductivity of Water-Ethylene Glycol-Al2O3 Nanofluids
by Dorota Sawicka, Janusz T. Cieśliński and Slawomir Smolen
Nanomaterials 2020, 10(8), 1487; https://doi.org/10.3390/nano10081487 - 29 Jul 2020
Cited by 18 | Viewed by 4330
Abstract
Because of their superb thermal conductivity, nanofluids are seen as new generation of cooling mediums in many engineering applications. It is well established that even a small amount of nanoparticles mixed with a base fluid may result in distinct thermal conductivity enhancement. On [...] Read more.
Because of their superb thermal conductivity, nanofluids are seen as new generation of cooling mediums in many engineering applications. It is well established that even a small amount of nanoparticles mixed with a base fluid may result in distinct thermal conductivity enhancement. On the other hand, addition of nanoparticles to the base fluid results in its substantial viscosity increase. Therefore, it is very difficult to evaluate the relative importance of viscosity and thermal conductivity of the nanofluid on convective heat transfer performance. In order to estimate such resultant impact properly, it is necessary to develop reliable correlation equations for predictions of these two thermophysical properties of nanofluids. In this paper, the thermal conductivity and dynamic viscosity of five fluids, i.e., pure water, ethylene glycol (EG) and three mixtures of water and EG with volume ratio of 40:60, 50:50 and 60:40 have been experimentally determined. The aforementioned fluids served as base fluids in nanofluids with Al2O3 nanoparticles at the concentration of 0.01%, 0.1% and 1% by weight. A set of 20 correlations for prediction of thermal conductivity and dynamic viscosity of base fluids and corresponding nanofluids has been developed. Moreover, present results have been confronted with literature data and predictions made by use of carefully selected recognized literature correlations. Full article
(This article belongs to the Special Issue Computational Modeling and Simulation for Nanomaterials, Nanotechnology, and Nanoscience)
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27 pages, 3912 KiB  
Article
Impact of the Interband Transitions in Gold and Silver on the Dynamics of Propagating and Localized Surface Plasmons
by Krystyna Kolwas and Anastasiya Derkachova
Nanomaterials 2020, 10(7), 1411; https://doi.org/10.3390/nano10071411 - 19 Jul 2020
Cited by 83 | Viewed by 7207
Abstract
Understanding and modeling of a surface-plasmon phenomenon on lossy metals interfaces based on simplified models of dielectric function lead to problems when confronted with reality. For a realistic description of lossy metals, such as gold and silver, in the optical range of the [...] Read more.
Understanding and modeling of a surface-plasmon phenomenon on lossy metals interfaces based on simplified models of dielectric function lead to problems when confronted with reality. For a realistic description of lossy metals, such as gold and silver, in the optical range of the electromagnetic spectrum and in the adjacent spectral ranges it is necessary to account not only for ohmic losses but also for the radiative losses resulting from the frequency-dependent interband transitions. We give a detailed analysis of Surface Plasmon Polaritons (SPPs) and Localized Surface Plasmons (LPSs) supported by such realistic metal/dielectric interfaces based on the dispersion relations both for flat and spherical gold and silver interfaces in the extended frequency and nanoparticle size ranges. The study reveals the region of anomalous dispersion for a silver flat interface in the near UV spectral range and high-quality factors for larger nanoparticles. We show that the frequency-dependent interband transition accounted in the dielectric function in a way allowing reproducing well the experimentally measured indexes of refraction does exert the pronounced impact not only on the properties of SPP and LSP for gold interfaces but also, with the weaker but not negligible impact, on the corresponding silver interfaces in the optical ranges and the adjacent spectral ranges. Full article
(This article belongs to the Special Issue Computational Modeling and Simulation for Nanomaterials, Nanotechnology, and Nanoscience)
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15 pages, 4784 KiB  
Article
Performance of Intrinsic and Modified Graphene for the Adsorption of H2S and CH4: A DFT Study
by Xin Gao, Qu Zhou, Jingxuan Wang, Lingna Xu and Wen Zeng
Nanomaterials 2020, 10(2), 299; https://doi.org/10.3390/nano10020299 - 10 Feb 2020
Cited by 88 | Viewed by 5688
Abstract
In this study, the adsorption performances of graphene before and after modification to H2S and CH4 molecules were studied using first principles with the density functional theory (DFT) method. The most stable adsorption configuration, the adsorption energy, the density of [...] Read more.
In this study, the adsorption performances of graphene before and after modification to H2S and CH4 molecules were studied using first principles with the density functional theory (DFT) method. The most stable adsorption configuration, the adsorption energy, the density of states, and the charge transfer are discussed to research the adsorption properties of intrinsic graphene (IG), Ni-doped graphene (Ni–G), vacancy defect graphene (DG), and graphene oxide (G–OH) for H2S and CH4. The weak adsorption and charge transfer of IG achieved different degrees of promotion by doping the Ni atom, setting a single vacancy defect, and adding oxygen-containing functional groups. It can be found that a single vacancy defect significantly enhances the strength of interaction between graphene and adsorbed molecules. DG peculiarly shows excellent adsorption performance for H2S, which is of great significance for the study of a promising sensor for H2S gas. Full article
(This article belongs to the Special Issue Computational Modeling and Simulation for Nanomaterials, Nanotechnology, and Nanoscience)
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16 pages, 1304 KiB  
Article
Effect of Domain Size, Boundary, and Loading Conditions on Mechanical Properties of Amorphous Silica: A Reactive Molecular Dynamics Study
by Truong Vo, Brett Reeder, Angelo Damone and Pania Newell
Nanomaterials 2020, 10(1), 54; https://doi.org/10.3390/nano10010054 - 25 Dec 2019
Cited by 20 | Viewed by 4108
Abstract
Mechanical properties are very important when choosing a material for a specific application. They help to determine the range of usefulness of a material, establish the service life, and classify and identify materials. The size effect on mechanical properties has been well established [...] Read more.
Mechanical properties are very important when choosing a material for a specific application. They help to determine the range of usefulness of a material, establish the service life, and classify and identify materials. The size effect on mechanical properties has been well established numerically and experimentally. However, the role of the size effect combined with boundary and loading conditions on mechanical properties remains unknown. In this paper, by using molecular dynamics (MD) simulations with the state-of-the-art ReaxFF force field, we study mechanical properties of amorphous silica (e.g., Young’s modulus, Poisson’s ratio) as a function of domain size, full-/semi-periodic boundary condition, and tensile/compressive loading. We found that the domain-size effect on Young’s modulus and Poisson’s ratio is much more significant in semi-periodic domains compared to full-periodic domains. The results, for the first time, revealed the bimodular and anisotropic nature of amorphous silica at the atomic level. We also defined a “safe zone” regarding the domain size, where the bulk properties of amorphous silica can be reproducible, while the computational cost and accuracy are in balance. Full article
(This article belongs to the Special Issue Computational Modeling and Simulation for Nanomaterials, Nanotechnology, and Nanoscience)
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13 pages, 9479 KiB  
Article
Numerical Analysis of the Correlation between Arc Plasma Fluctuation and Nanoparticle Growth–Transport under Atmospheric Pressure
by Masaya Shigeta, Manabu Tanaka and Emanuele Ghedini
Nanomaterials 2019, 9(12), 1736; https://doi.org/10.3390/nano9121736 - 6 Dec 2019
Cited by 11 | Viewed by 3961
Abstract
A time-dependent two-dimensional (2D) axisymmetric simulation was conducted for arc plasma with dynamically fluctuating fluid generating iron nanoparticles in a direct-current discharge condition. The nonequilibrium process of simultaneous growth and transport of nanoparticles is simulated using a simple model with a low computational [...] Read more.
A time-dependent two-dimensional (2D) axisymmetric simulation was conducted for arc plasma with dynamically fluctuating fluid generating iron nanoparticles in a direct-current discharge condition. The nonequilibrium process of simultaneous growth and transport of nanoparticles is simulated using a simple model with a low computational cost. To ascertain fluid dynamic instability and steep gradients in plasma temperature and particle distributions, a highly accurate method is adopted for computation. The core region of the arc plasma is almost stationary, whereas the fringe fluctuates because of fluid dynamic instability between the arc plasma and the shielding gas. In the downstream region, the vapor molecules decrease by condensation. The nanoparticles decrease by coagulation. These results suggest that both of the simultaneous processes make important contributions to particle growth. The fluctuation of nanoparticle number density in a distant region exhibits stronger correlation with the temperature fluctuation at the plasma fringe. The correlation analysis results suggest that the distribution of growing nanoparticles distant from the arc plasma can be controlled via control of temperature fluctuation at the arc plasma fringe. Full article
(This article belongs to the Special Issue Computational Modeling and Simulation for Nanomaterials, Nanotechnology, and Nanoscience)
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17 pages, 14223 KiB  
Article
Super Ductility of Nanoglass Aluminium Nitride
by Yinbo Zhao, Xianghe Peng, Cheng Huang, Bo Yang, Ning Hu and Mingchao Wang
Nanomaterials 2019, 9(11), 1535; https://doi.org/10.3390/nano9111535 - 29 Oct 2019
Cited by 7 | Viewed by 3394
Abstract
Ceramics have been widely used in many fields because of their distinctive properties, however, brittle fracture usually limits their application. To solve this problem, nanoglass ceramics were developed. In this article, we numerically investigated the mechanical properties of nanoglass aluminium nitride (ng-AlN) with [...] Read more.
Ceramics have been widely used in many fields because of their distinctive properties, however, brittle fracture usually limits their application. To solve this problem, nanoglass ceramics were developed. In this article, we numerically investigated the mechanical properties of nanoglass aluminium nitride (ng-AlN) with different glassy grain sizes under tension using molecular dynamics simulations. It was found that ng-AlN exhibits super ductility and tends to deform uniformly without the formation of voids as the glassy grain size decreases to about 1 nm, which was attributed to a large number of uniformly distributed shear transformation zones (STZs). We further investigated the effects of temperature and strain rate on ng-AlNd = 1 nm, which showed that temperature insignificantly influences the elastic modulus, while the dependence of the ultimate strength on temperature follows the T2/3 scaling law. Meanwhile, the ultimate strength of ng-AlNd = 1 nm is positively correlated with the strain rate, following a power function relationship. Full article
(This article belongs to the Special Issue Computational Modeling and Simulation for Nanomaterials, Nanotechnology, and Nanoscience)
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10 pages, 2976 KiB  
Article
Endohedral Fullerene Fe@C28 Adsorbed on Au(111) Surface as a High-Efficiency Spin Filter: A Theoretical Study
by Ke Xu, Tie Yang, Yu Feng, Xin Ruan, Zhenyan Liu, Guijie Liang and Xiaotian Wang
Nanomaterials 2019, 9(8), 1068; https://doi.org/10.3390/nano9081068 - 25 Jul 2019
Cited by 5 | Viewed by 3239
Abstract
We present a theoretical study on the adsorption and spin transport properties of magnetic Fe@C28 using Ab initio calculations based on spin density functional theory and non-equilibrium Green’s function techniques. Fe@C28 tends to adsorb on the bridge sites in the manner [...] Read more.
We present a theoretical study on the adsorption and spin transport properties of magnetic Fe@C28 using Ab initio calculations based on spin density functional theory and non-equilibrium Green’s function techniques. Fe@C28 tends to adsorb on the bridge sites in the manner of C–C bonds, and the spin-resolved transmission spectra of Fe@C28 molecular junctions exhibit robust transport spin polarization (TSP). Under small bias voltage, the transport properties of Fe@C28 are mainly determined by the spin-down channel and exhibit a large spin polarization. When compressing the right electrode, the TSP is decreased, but high spin filter efficiency (SFE) is still maintained. These theoretical results indicate that Fe@C28 with a large magnetic moment has potential applications in molecular spintronics. Full article
(This article belongs to the Special Issue Computational Modeling and Simulation for Nanomaterials, Nanotechnology, and Nanoscience)
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14 pages, 4572 KiB  
Article
A New Model to Predict Optimum Conditions for Growth of 2D Materials on a Substrate
by Yu-Peng Liu, Bo-Yuan Ning, Le-Cheng Gong, Tsu-Chien Weng and Xi-Jing Ning
Nanomaterials 2019, 9(7), 978; https://doi.org/10.3390/nano9070978 - 5 Jul 2019
Cited by 11 | Viewed by 3236
Abstract
Deposition of atoms or molecules on a solid surface is a flexible way to prepare various novel two-dimensional materials if the growth conditions, such as suitable surface and optimum temperature, could be predicted theoretically. However, prediction challenges modern theory of material design because [...] Read more.
Deposition of atoms or molecules on a solid surface is a flexible way to prepare various novel two-dimensional materials if the growth conditions, such as suitable surface and optimum temperature, could be predicted theoretically. However, prediction challenges modern theory of material design because the free energy criteria can hardly be applied to this issue due to the long-standing problem in statistical physics of the calculations of the free energy. Herein, we present an approach to the problem by the demonstrations of graphene and γ-graphyne on the surface of copper crystal, as well as silicene on a silver substrate. Compared with previous state-of-the-art algorithms for calculations of the free energy, our approach is capable of achieving computational precisions at least 10-times higher, which was confirmed by molecular dynamics simulations, and working at least four orders of magnitude faster, which enables us to obtain free energy based on ab initio calculations of the interaction potential instead of the empirical one. The approach was applied to predict the optimum conditions for silicene growth on different surfaces of solid silver based on density functional theory, and the results are in good agreement with previous experimental observations. Full article
(This article belongs to the Special Issue Computational Modeling and Simulation for Nanomaterials, Nanotechnology, and Nanoscience)
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10 pages, 1031 KiB  
Article
Small-Angle Scattering from Weakly Correlated Nanoscale Mass Fractal Aggregates
by Eugen Mircea Anitas
Nanomaterials 2019, 9(4), 648; https://doi.org/10.3390/nano9040648 - 22 Apr 2019
Cited by 13 | Viewed by 4106
Abstract
Formation of fractal aggregates is generally an undesired effect which may lead to end products with worse properties as compared to those of the individual components, especially in nanocomposite materials. Although several methods exist to overcome this issue, such as inclusion of additives, [...] Read more.
Formation of fractal aggregates is generally an undesired effect which may lead to end products with worse properties as compared to those of the individual components, especially in nanocomposite materials. Although several methods exist to overcome this issue, such as inclusion of additives, irradiation grafting or sonication, their effectiveness relies on a detailed knowledge of the structural properties of the aggregates. Here, small-angle scattering (SAS) technique is used and a theoretical model based on a unified Guinier–Porod approach with weak correlations is developed for investigating the structural properties of nanoscale fractal aggregates. It is shown how one can extract information concerning the correlation length/degree between aggregates, their fractal dimension and the overall size. These parameters can be used for development of various types of novel nanomaterials with pre-determined properties and functions. Full article
(This article belongs to the Special Issue Computational Modeling and Simulation for Nanomaterials, Nanotechnology, and Nanoscience)
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13 pages, 3358 KiB  
Article
Opto-thermally Excited Fabry-Perot Resonance Frequency Behaviors of Clamped Circular Graphene Membrane
by Fu-Tao Shi, Shang-Chun Fan, Cheng Li and Zi-Ang Li
Nanomaterials 2019, 9(4), 563; https://doi.org/10.3390/nano9040563 - 7 Apr 2019
Cited by 8 | Viewed by 3528
Abstract
An opto-thermally excited optical fiber Fabry-Perot (F-P) resonant probe with suspended clamped circular graphene diaphragm is presented in this paper. Then, the dependence of resonance frequency behaviors of graphene diaphragm upon opto-mechanical factors including membrane properties, laser excitation parameters and film boundary conditions [...] Read more.
An opto-thermally excited optical fiber Fabry-Perot (F-P) resonant probe with suspended clamped circular graphene diaphragm is presented in this paper. Then, the dependence of resonance frequency behaviors of graphene diaphragm upon opto-mechanical factors including membrane properties, laser excitation parameters and film boundary conditions are investigated via COMSOL Multiphysics simulation. The results show that the radius and thickness of membrane will linearly affect the optical fiber light-induced temperature distribution, thus resulting in rapidly decreasing resonance frequency changes with the radius-to-thickness ratio. Moreover, the prestress can be regulated in the range of 108 Pa to 109 Pa by altering the environmental temperature with a scale factor of 14.2 MPa/K. It is important to note that the availability of F-P resonant probe with a defective clamped circular graphene membrane can be improved notably by fabricating the defected circular membrane to a double-end clamped beam, which gives a broader perspective to characterize the resonance performance of opto-thermally excited F-P resonators. Full article
(This article belongs to the Special Issue Computational Modeling and Simulation for Nanomaterials, Nanotechnology, and Nanoscience)
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