scholarly journals Direct imaging, three-dimensional interaction spectroscopy, and friction anisotropy of atomic-scale ripples on MoS2

2020 ◽  
Vol 4 (1) ◽  
Author(s):  
Omur E. Dagdeviren ◽  
Ogulcan Acikgoz ◽  
Peter Grütter ◽  
Mehmet Z. Baykara
Keyword(s):  
Three Dimensional ◽  
Atomic Scale ◽  
Direct Imaging ◽  
Friction Anisotropy ◽  
Dimensional Interaction

scholarly journals Porous Characteristics of Three-Dimensional Disordered Graphene Networks

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 127
Author(s):  
YongChao Wang ◽  
YinBo Zhu ◽  
HengAn Wu
Keyword(s):  
Pore Size ◽  
Low Temperatures ◽  
Gas Adsorption ◽  
Three Dimensional ◽  
Md Simulations ◽  
Structural Features ◽  
Atomic Scale ◽  
Critical Factors ◽  
Chlorination Process ◽  
Porous Morphology

The porous characteristics of disordered carbons are critical factors to their performance on hydrogen storage and electrochemical capacitors. Even though the porous information can be estimated indirectly by gas adsorption experiments, it is still hard to directly characterize the porous morphology considering the complex 3D connectivity. To this end, we construct full-atom disordered graphene networks (DGNs) by mimicking the chlorination process of carbide-derived carbons using annealing-MD simulations, which could model the structure of disordered carbons at the atomic scale. The porous characteristics, including pore volume, pore size distribution (PSD), and specific surface area (SSA), were then computed from the coordinates of carbon atoms. From the evolution of structural features, pores grow dramatically during the formation of polyaromatic fragments and sequent disordered framework. Then structure is further graphitized while the PSD shows little change. For the obtained DGNs, the porosity, pore size, and SSA increase with decreasing density. Furthermore, SSA tends to saturate in the low-density range. The DGNs annealed at low temperatures exhibit larger SSA than high-temperature DGNs because of the abundant free edges.

Thermal Design of Highly-Efficient Thermoelectric Materials With Atomic-Scale Three-Dimensional Phononic Crystals

2007 ◽  
Author(s):  
Jean-Numa Gillet ◽  
Yann Chalopin ◽  
Sebastian Volz
Keyword(s):  
Thermal Conductivity ◽  
Bulk Material ◽  
Phononic Crystal ◽  
Three Dimensional ◽  
Mean Free Path ◽  
Dispersion Curves ◽  
Phononic Crystals ◽  
Thermal Design ◽  
Atomic Scale ◽  
Thermal Insulating

Owing to their thermal insulating properties, superlattices have been extensively studied. A breakthrough in the performance of thermoelectric devices was achieved by using superlattice materials. The problem of those nanostructured materials is that they mainly affect heat transfer in only one direction. In this paper, the concept of canceling heat conduction in the three spatial directions by using atomic-scale three-dimensional (3D) phononic crystals is explored. A period of our atomic-scale 3D phononic crystal is made up of a large number of diamond-like cells of silicon atoms, which form a square supercell. At the center of each supercell, we substitute a smaller number of Si diamond-like cells by other diamond-like cells, which are composed of germanium atoms. This elementary heterostructure is periodically repeated to form a Si/Ge 3D nanostructure. To obtain different atomic configurations of the phononic crystal, the number of Ge diamond-like cells at the center of each supercell can be varied by substitution of Si diamond-like cells. The dispersion curves of those atomic configurations can be computed by lattice dynamics. With a general equation, the thermal conductivity of our atomic-scale 3D phononic crystal can be derived from the dispersion curves. The thermal conductivity can be reduced by at least one order of magnitude in an atomic-scale 3D phononic crystal compared to a bulk material. This reduction is due to the decrease of the phonon group velocities without taking into account that of the phonon average mean free path.

Three-Dimensional Interaction Effects in an Internally Multicracked Pressurized Thick-Walled Cylinder— Part I: Radial Crack Arrays

1996 ◽  
Vol 118 (3) ◽  
pp. 357-363 ◽  
Author(s):  
M. Perl ◽  
C. Levy ◽  
J. Pierola
Keyword(s):  
Radial Crack ◽  
Crack Depth ◽  
Three Dimensional ◽  
Internal Surface ◽  
Interaction Effects ◽  
Life Assessment ◽  
Fatigue Life Assessment ◽  
Dimensional Interaction ◽  
Least Squares Fit ◽  
Wide Range

Under certain conditions, numerous internal surface cracks develop in pressurized thick-walled cylinders, both in the radial and longitudinal directions. For fatigue life assessment of such vessels, the 3-D interaction effects among these cracks on the prevailing stress intensity factors (SIFs) need evaluation. In Part I of this paper, radial crack arrays are considered exclusively. The mode I SIF distribution for a wide range of semi-circular and semi-elliptical cracks are evaluated. The 3-D analysis is performed via the finite element method with the submodeling technique, employing singular elements along the crack front. SIFs are evaluated for arrays of up to n = 180 cracks; for a wide range of crack depth to wall thickness ratios, a/t, from 0.05 to 0.6; and, for various ellipticities of the crack, i.e., the ratio of crack depth to semicrack length, a/c, from 0.2 to 2. Using a least-squares fit, two simple expressions for the most critical (n = 2) SIFs are obtained for sparse and dense crack arrays. The formulas, which are functions of a/t and a/c, are of very good engineering accuracy. The results clearly indicate that the SIFs are considerably affected by the interaction among the cracks in the array as well as the three-dimensionality of the problem. In Part II of this paper, the interaction effects between longitudinal coplanar cracks will be analyzed.

scholarly journals Nanometer Scale Tomographic Investigation of Fine Scale Precipitates in a CuFeNi Granular System by Three-Dimensional Field Ion Microscopy

2012 ◽  
Vol 18 (5) ◽  
pp. 1129-1134 ◽  
Author(s):  
Sophie Cazottes ◽  
François Vurpillot ◽  
Abdeslem Fnidiki ◽  
Dany Lemarchand ◽  
Marcello Baricco ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Precise Determination ◽  
Atomic Scale ◽  
Granular System ◽  
Field Ion Microscopy ◽  
Mean Diameter ◽  
The Matrix ◽  
The Mean ◽  
Ion Microscopy

AbstractThe microstructure of Cu80Fe10Ni10 (at. %) granular ribbons was investigated by means of three-dimensional field ion microscopy (3D FIM). This ribbon is composed of magnetic precipitates embedded in a nonmagnetic matrix. The magnetic precipitates have a diameter smaller than 5 nm in the as-spun state and are coherent with the matrix. No accurate characterization of such a microstructure has been performed so far. A tomographic characterization of the microstructure of melt spun and annealed Cu80Fe10Ni10 ribbon was achieved with 3D FIM at the atomic scale. A precise determination of the size distribution, number density, and distance between the precipitates was carried out. The mean diameter for the precipitates is 4 nm in the as-spun state. After 2 h at 350°C, there is an increase of the size of the precipitates, while after 2 h at 400°C the mean diameter of the precipitates decreases. Those data were used as inputs in models that describe the magnetic and magnetoresistive properties of this alloy.

Three-dimensional atomic-scale investigation of ZnO-MgxZn1−xO m-plane heterostructures

2017 ◽  
Vol 111 (3) ◽  
pp. 032108 ◽  
Author(s):  
E. Di Russo ◽  
L. Mancini ◽  
F. Moyon ◽  
S. Moldovan ◽  
J. Houard ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Atomic Scale

scholarly journals Creation and Evaluation of Atomically Ordered Side- and Facet-Surface Structures of Three-Dimensional Silicon Nano-Architectures

2020 ◽  
Author(s):  
Azusa N. Hattori ◽  
Ken Hattori
Keyword(s):  
Electron Diffraction ◽  
Surface Science ◽  
Three Dimensional ◽  
Annealing Treatment ◽  
High Energy ◽  
Energy Electron ◽  
Atomic Scale ◽  
Methods Of Evaluation ◽  
Facet Surface ◽  
Microscopy Techniques

The realization of three-dimensional (3D)-architected nanostructures, that is, the transformation from novel two-dimensional (2D) film-based devices to 3D complex nanodevices, is of crucial importance with the progress of scaling down devices to nanometer order. However, little attention has been devoted to controlling the atomic ordering and structures of side-surfaces on 3D structures, while techniques for controlling and investigating 2D surfaces, namely, surface science, have been established only for planar 2D surfaces. We have established an original methodology that enables atomic orderings and arrangements of surfaces with arbitrary directions to be observed on 3D figured structures by developing diffraction and microscopy techniques. An original technique, namely, directly and quantitatively viewing the side- and facet-surfaces at the atomic scale by reflection high-energy electron diffraction (RHEED) and low-energy electron diffraction (LEED), can be used to determine process parameters in etching. This chapter introduces methods of evaluation by RHEED and LEED based on a reciprocal space map and methods of creating various atomically flat 111 and {100} side-surfaces of 3D Si nano-architectures and tilted 111 facet-surfaces fabricated by lithography dry and wet etching processes, followed by annealing treatment in vacuum.

Atomic-scale simulations of strain localization in a single-component three-dimensional model amorphous solid

2005 ◽  
Vol 903 ◽  
Author(s):  
Yunfeng Shi ◽  
Michael L Falk
Keyword(s):  
Shear Bands ◽  
Three Dimensional ◽  
Amorphous Solid ◽  
Single Component ◽  
Atomic Scale ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Localized Deformation ◽  
Cooling Rates ◽  
High Cooling Rates

AbstractMolecular dynamics is used to simulate model non-crystalline solids described by a single-component Dzugutov system. The solids are produced by quenching equilibrium liquids at different cooling rates. These are then tested in uniaxial compression. Samples produced at high cooling rates exhibit homogenous deformation while samples quenched at low cooling rates exhibit localized deformation. Shear bands are shown to correspond to regions of depleted short-range order as determined by a Frank-Kasper criterion.

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