Mechanical response of all-MoS2 single-layer heterostructures: a ReaxFF investigation

AbstractA systematic study of the structure-mechanical properties relationship is reported for MoSi2-SiC nanolayer composites. Alternating layers of MoSi2 and SiC were synthesized by DCmagnetron and if-diode sputtering, respectively. Cross-sectional transmission electron microscopy was used to examine three distinct reactions in the specimens when exposed to different annealing conditions: crystallization and phase transformation of MoSi2, crystallization of SiC, and spheroidization of the layer structures. Nanoindentation was employed to characterize the mechanical response as a function of the structural changes. As-sputtered material exhibits amorphous structures in both types of layers and has a hardness of 11GPa and a modulus of 217GPa. Subsequent heat treatment induces crystallization of MoSi2 to form the C40 structure at 500°C and SiC to form the a structure at 700°C. The crystallization process is directly responsible for the hardness and modulus increase in the multilayers. A hardness of 24GPa and a modulus of 340GPa can be achieved through crystallizing both MoSi2 and SiC layers. Annealing at 900°C for 2h causes the transformation of MoSi2 into the Cllb structure, as well as spheroidization of the layering to form a nanocrystalline equiaxed microstructure. A slight degradation in hardness but not in modulus is observed accompanying the layer break-down.

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Differences in the Mechanical Properties of Monolayer and Multilayer WSe2/MoSe2

MRS Advances ◽

10.1557/adv.2018.246 ◽

2018 ◽

Vol 3 (6-7) ◽

pp. 373-378

Author(s):

Y. M. Jaques ◽

P. Manimunda ◽

Y. Nakanishi ◽

S. Susarla ◽

C. F. Woellner ◽

...

Keyword(s):

Mechanical Properties ◽

Transition Metal Dichalcogenides ◽

Single Layer ◽

Silicon Substrates ◽

2D Layered Materials ◽

Layer Structures ◽

Crystal Properties ◽

Metal Dichalcogenides ◽

Optical And Mechanical Properties ◽

Dynamics Simulations

ABSTRACTTransition metal dichalcogenides are 2D structures with remarkable electronic, chemical, optical and mechanical properties. Monolayer and crystal properties of these structures have been extensively investigated, but a detailed understanding of the properties of their few-layer structures are still missing. In this work we investigated the mechanical differences between monolayer and multilayer WSe2 and MoSe2, through fully atomistic molecular dynamics simulations (MD). It was observed that single layer WSe2/MoSe2 deposited on silicon substrates have larger friction coefficients than 2, 3 and 4 layered structures. For all considered cases it is always easier to peel off and/or to fracture MoSe2 structures. These results suggest that the interactions between first layer and substrate are stronger than interlayer interactions themselves. Similar findings have been reported for other nanomaterials and it has been speculated whether this is a universal-like behavior for 2D layered materials. We have also analyzed fracture patterns. Our results show that fracture is chirality dependent with crack propagation preferentially perpendicular to W(Mo)-Se bonds and faster for zig-zag-like defects.

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Improving the Properties of Sapphire by Coatings

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.26-28.619 ◽

2007 ◽

Vol 26-28 ◽

pp. 619-622 ◽

Cited By ~ 1

Author(s):

Li Ping Feng ◽

Zheng Tang Liu

Keyword(s):

Mechanical Properties ◽

Surface Morphology ◽

High Temperatures ◽

Room Temperature ◽

Single Layer ◽

Sio2 Film ◽

Flexure Strength ◽

Bending Tests ◽

Optical And Mechanical Properties ◽

Α Al2o3

SiO2 coatings and double layer films of SiO2/Si3N4 have been designed and prepared on sapphire (α-Al2O3) by radio frequency magnetron reactive sputtering in order to improve the optical and mechanical properties of infrared windows of sapphire. The transmission of the coated and uncoated sapphire in the wavelength range from 2.5 to 6.7um was determined. Surface morphology and roughness of coated and uncoated sapphire have been measured using a talysurf. The flexure strength of coated and uncoated sapphire samples has been studied by 3-point bending tests at room temperature and high temperatures. The results show that the coatings can improve the surface morphology and reduce the surface roughness of sapphire substrate. What’s more, the designed single layer of SiO2 film and two-layer of SiO2/Si3N4 films can both increase the transmission of sapphire in mid-wave IR and strengthen sapphire at high temperatures. Coated sapphire transmits over 95% at wavelength from 3 to 5um for the two designs. Flexure tests reveal that SiO2 coatings and SiO2/Si3N4 films increase the strength of c-axis sapphire by a factor of about 1.5 and 1.4, respectively, at 800°C.

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Influence of Restraining Stiffness on Mechanical Properties of Suspen-Dome

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.163-167.754 ◽

2010 ◽

Vol 163-167 ◽

pp. 754-759

Author(s):

Jia Min Guo ◽

Shi Lin Dong ◽

Xing Fei Yuan ◽

Yong Li Hou

Keyword(s):

Mechanical Properties ◽

Mechanical Response ◽

Dynamic Properties ◽

Single Layer ◽

Hybrid Structure ◽

Static Response ◽

Large Span ◽

Lattice Shell

Suspen-dome is a kind of large-span prestressed hybrid structure, To understand the influence of radial restraining stiffness to structural mechanical response, and to ensure radial restraining stiffness reliable during designing, a rib 3 type suspen-dome and corresponding single layer lattice shell were selected, their static response under different radial restraining stiffness were studied and compared .At the same time, basic dynamic properties of a rib 3 type suspen-dome were analyzed under different radial restraining stiffness. The results show that the sensitivity of single layer dome mechanical response to radial restraining stiffness will be reduced because of the bottom cable-struts, enhance of radial restraining stiffness will not influence structural mechanical response after radial restraining stiffness reaches certain value.

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Mechanical Properties and Dislocation Structure of Single Crystal Cdte Deformed in Compression at 300°C

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010009292x ◽

1976 ◽

Vol 34 ◽

pp. 592-593

Author(s):

Ernest L. Hall ◽

J. B. Vander Sande

Keyword(s):

Mechanical Properties ◽

Single Crystal ◽

Dislocation Structure ◽

Room Temperature ◽

Elevated Temperatures ◽

Strain Curve ◽

Optical Devices ◽

Semiconductor Compound ◽

Wide Range ◽

Sample Orientation

The present paper describes research on the mechanical properties and related dislocation structure of CdTe, a II-VI semiconductor compound with a wide range of uses in electrical and optical devices. At room temperature CdTe exhibits little plasticity and at the same time relatively low strength and hardness. The mechanical behavior of CdTe was examined at elevated temperatures with the goal of understanding plastic flow in this material and eventually improving the room temperature properties. Several samples of single crystal CdTe of identical size and crystallographic orientation were deformed in compression at 300°C to various levels of total strain. A resolved shear stress vs. compressive glide strain curve (Figure la) was derived from the results of the tests and the knowledge of the sample orientation.

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Comparison of Substructures Between Uniaxial and Biaxial Deformation in 1100-0 Aluminum

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100096989 ◽

1981 ◽

Vol 39 ◽

pp. 52-53

Author(s):

D. L. Rohr ◽

S. S. Hecker

Keyword(s):

Plastic Strain ◽

Cell Walls ◽

Room Temperature ◽

Mechanical Response ◽

Biaxial Tension ◽

Initial Deformation ◽

Uniaxial Deformation ◽

Biaxial Deformation ◽

Stress States ◽

Comprehensive Study

As part of a comprehensive study of microstructural and mechanical response of metals to uniaxial and biaxial deformations, the development of substructure in 1100 A1 has been studied over a range of plastic strain for two stress states.Specimens of 1100 aluminum annealed at 350 C were tested in uniaxial (UT) and balanced biaxial tension (BBT) at room temperature to different strain levels. The biaxial specimens were produced by the in-plane punch stretching technique. Areas of known strain levels were prepared for TEM by lapping followed by jet electropolishing. All specimens were examined in a JEOL 200B run at 150 and 200 kV within 24 to 36 hours after testing.The development of the substructure with deformation is shown in Fig. 1 for both stress states. Initial deformation produces dislocation tangles, which form cell walls by 10% uniaxial deformation, and start to recover to form subgrains by 25%. The results of several hundred measurements of cell/subgrain sizes by a linear intercept technique are presented in Table I.

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Autonomous self-healing polyisoprene elastomers with high modulus and good toughness based on the synergy of dynamic ionic crosslinks and highly disordered crystals

Polymer Chemistry ◽

10.1039/d0py01034k ◽

2020 ◽

Vol 11 (41) ◽

pp. 6549-6558

Author(s):

Yohei Miwa ◽

Mayu Yamada ◽

Yu Shinke ◽

Shoichi Kutsumizu

Keyword(s):

Mechanical Properties ◽

Room Temperature ◽

Self Healing ◽

High Modulus ◽

Disordered Crystals ◽

Ionic Crosslinks

We designed a novel polyisoprene elastomer with high mechanical properties and autonomous self-healing capability at room temperature facilitated by the coexistence of dynamic ionic crosslinks and crystalline components that slowly reassembled.

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Cracking at the fold in double layer coated paper: the influence of latex and starch composition

TAPPI Journal ◽

10.32964/tj18.2.93 ◽

2019 ◽

Vol 18 (2) ◽

pp. 93-99

Author(s):

SEYYED MOHAMMAD HASHEMI NAJAFI ◽

DOUGLAS BOUSFIELD, ◽

MEHDI TAJVIDI

Keyword(s):

Mechanical Properties ◽

Double Layer ◽

Starch Content ◽

Single Layer ◽

Double Layers ◽

Coated Paper ◽

Coated Papers ◽

Coating Layers ◽

Scanned Images ◽

Packaging Paper

Cracking at the fold of publication and packaging paper grades is a serious problem that can lead to rejection of product. Recent work has revealed some basic mechanisms and the influence of various parameters on the extent of crack area, but no studies are reported using coating layers with known mechanical properties, especially for double-coated systems. In this study, coating layers with different and known mechanical properties were used to characterize crack formation during folding. The coating formulations were applied on two different basis weight papers, and the coated papers were folded. The binder systems in these formulations were different combinations of a styrene-butadiene latex and mixtures of latex and starch for two different pigment volume concentrations (PVC). Both types of papers were coated with single and double layers. The folded area was scanned with a high-resolution scanner while the samples were kept at their folded angle. The scanned images were analyzed within a constant area. The crack areas were reported for different types of papers, binder system and PVC values. As PVC, starch content, and paper basis weight increased, the crack area increased. Double layer coated papers with high PVC and high starch content at the top layer had more cracks in comparison with a single layer coated paper, but when the PVC of the top layer was low, cracking area decreased. No measurable cracking was observed when the top layer was formulated with a 100% latex layer.

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