scholarly journals Contact probing of stretched membranes and adhesive interactions: graphene and other two-dimensional materials

2016 ◽  
Vol 472 (2195) ◽  
pp. 20160550 ◽  
Author(s):  
Feodor M. Borodich ◽  
Boris A. Galanov
Keyword(s):  
2D Materials ◽  
Contact Problems ◽  
Adhesive Contact ◽  
Contact Radius ◽  
Elastic Membrane ◽  
Displacement Curve ◽  
Circular Membrane ◽  
Two Dimensional ◽  
Adhesive Interactions ◽  
Force Displacement

Contact probing is the preferable method for studying mechanical properties of thin two-dimensional (2D) materials. These studies are based on analysis of experimental force–displacement curves obtained by loading of a stretched membrane by a probe of an atomic force microscope or a nanoindenter. Both non-adhesive and adhesive contact interactions between such a probe and a 2D membrane are studied. As an example of the 2D materials, we consider a graphene crystal monolayer whose discrete structure is modelled as a 2D isotropic elastic membrane. Initially, for contact between a punch and the stretched circular membrane, we formulate and solve problems that are analogies to the Hertz-type and Boussinesq frictionless contact problems. A general statement for the slope of the force–displacement curve is formulated and proved. Then analogies to the JKR (Johnson, Kendall and Roberts) and the Boussinesq–Kendall contact problems in the presence of adhesive interactions are formulated. General nonlinear relations among the actual force, displacements and contact radius between a sticky membrane and an arbitrary axisymmetric indenter are derived. The dimensionless form of the equations for power-law shaped indenters has been analysed, and the explicit expressions are derived for the values of the pull-off force and corresponding critical contact radius.

Non-direct estimations of adhesive and elastic properties of materials by depth-sensing indentation

2008 ◽  
Vol 464 (2098) ◽  
pp. 2759-2776 ◽  
Author(s):  
Feodor M Borodich ◽  
Boris A Galanov
Keyword(s):  
Experimental Data ◽  
Elastic Properties ◽  
Measurement Errors ◽  
Direct Determination ◽  
Adhesive Contact ◽  
Work Of Adhesion ◽  
Displacement Curve ◽  
Depth Sensing ◽  
Adhesive Properties ◽  
Force Displacement

Using the connection between depth-sensing indentation by spherical indenters and mechanics of adhesive contact, a new method for non-direct determination of adhesive and elastic properties of contacting materials is proposed. At low loads, the force–displacement curves reflect not only elastic properties but also adhesive properties of the contact, and therefore one can try to extract from experiments both the elastic characteristics of contacting materials (such as the reduced elastic modulus) and characteristics of molecular adhesion (such as the work of adhesion and the pull-off force) using a non-direct approach. The direct methods of estimations of the adhesive characteristics of materials currently used in experiments are rather complicated due to the instability of the experimental force–displacement diagrams for ultra-low tensile forces. The proposed method is based on the use of the stable experimental data for the elastic stage of the force–displacement curve and the mechanics of adhesive contact for spherical indenters. Since the experimental data always have some measurement errors, mathematical techniques for solving ill-posed problems are employed.

scholarly journals Adhesive contact problems for a thin elastic layer: Asymptotic analysis and the JKR theory

2018 ◽  
Vol 24 (5) ◽  
pp. 1405-1424 ◽  
Author(s):  
Feodor M. Borodich ◽  
Boris A. Galanov ◽  
Nikolay V. Perepelkin ◽  
Danila A. Prikazchikov
Keyword(s):  
Elastic Foundation ◽  
Elastic Layer ◽  
Order Approximation ◽  
Contact Problems ◽  
Adhesive Contact ◽  
Contact Radius ◽  
Direct Derivation ◽  
Compressible Elastic Layer ◽  
Jkr Theory ◽  
Thin Elastic Layer

Contact problems for a thin compressible elastic layer attached to a rigid support are studied. Assuming that the thickness of the layer is much less than the characteristic dimension of the contact area, a direct derivation of asymptotic relations for displacements and stress is presented. The proposed approach is compared with other published approaches. The cases are established when the leading-order approximation to the non-adhesive contact problems is equivalent to contact problem for a Winkler–Fuss elastic foundation. For this elastic foundation, the axisymmetric adhesive contact is studied in the framework of the Johnson–Kendall–Roberts (JKR) theory. The JKR approach has been generalized to the case of the punch shape being described by an arbitrary blunt axisymmetric indenter. Connections of the results obtained to problems of nanoindentation in the case that the indenter shape near the tip has some deviation from its nominal shape are discussed. For indenters whose shape is described by power-law functions, the explicit expressions are derived for the values of the pull-off force and for the corresponding critical contact radius.

scholarly journals Explicit transformation between non-adhesive and adhesive contact problems by means of the classical Johnson–Kendall–Roberts formalism

2021 ◽  
Vol 379 (2203) ◽  
pp. 20200374
Author(s):  
Nikolay V. Perepelkin ◽  
Feodor M. Borodich
Keyword(s):  
Rotational Symmetry ◽  
A Priori ◽  
Contact Problems ◽  
Adhesive Contact ◽  
Elastic Half Space ◽  
Principle Of Superposition ◽  
Linear Elastic ◽  
Thin Elastic Layer ◽  
Force Displacement ◽  
Superposition Of Solutions

The classic Johnson–Kendall–Roberts (JKR) contact theory was developed for frictionless adhesive contact between two isotropic elastic spheres. The advantage of the classical JKR formalism is the use of the principle of superposition of solutions to non-adhesive axisymmetric contact problems. In the recent years, the JKR formalism has been extended to other cases, including problems of contact between an arbitrary-shaped blunt axisymmetric indenter and a linear elastic half-space obeying rotational symmetry of its elastic properties. Here the most general form of the JKR formalism using the minimal number of a priori conditions is studied. The corresponding condition of energy balance is developed. For the axisymmetric case and a convex indenter, the condition is reduced to a set of expressions allowing explicit transformation of force–displacement curves from non-adhesive to corresponding adhesive cases. The implementation of the developed theory is demonstrated by presentation of a two-term asymptotic adhesive solution of the contact between a thin elastic layer and a rigid punch of arbitrary axisymmetric shape. Some aspects of numerical implementation of the theory by means of Finite-Element Method are also discussed. This article is part of a discussion meeting issue ‘A cracking approach to inventing new tough materials: fracture stranger than friction’.

Co-planar two-dimensional Metal-Insulator-Semiconductor Capacitor: Numerical study of the device electrostatics.

2017 ◽  
Author(s):  
Varun Bheemireddy
Keyword(s):  
Space Charge ◽  
High Performance ◽  
Numerical Study ◽  
2D Materials ◽  
Space Charge Density ◽  
Two Dimensional ◽  
Short Channel ◽  
Metal Insulator ◽  
Metal Insulator Semiconductor ◽  
New Family

The two-dimensional(2D) materials are highly promising candidates to realise elegant and e cient transistor. In the present letter, we conjecture a novel co-planar metal-insulator-semiconductor(MIS) device(capacitor) completely based on lateral 2D materials architecture and perform numerical study of the capacitor with a particular emphasis on its di erences with the conventional 3D MIS electrostatics. The space-charge density features a long charge-tail extending into the bulk of the semiconductor as opposed to the rapid decay in 3D capacitor. Equivalently, total space-charge and semiconductor capacitance densities are atleast an order of magnitude more in 2D semiconductor. In contrast to the bulk capacitor, expansion of maximum depletion width in 2D semiconductor is observed with increasing doping concentration due to lower electrostatic screening. The heuristic approach of performance analysis(2D vs 3D) for digital-logic transistor suggest higher ON-OFF current ratio in the long-channel limit even without third dimension and considerable room to maximise the performance of short-channel transistor. The present results could potentially trigger the exploration of new family of co-planar at transistors that could play a signi significant role in the future low-power and/or high performance electronics.<br>

Recent Advances and Need of Green Synthesis in Two-Dimensional Materials for Energy Conversion and Storage Applications

2021 ◽  
Vol 16 ◽  
Author(s):  
Joice Sophia Ponraj ◽  
Muniraj Vignesh Narayanan ◽  
Ranjith Kumar Dharman ◽  
Valanarasu Santiyagu ◽  
Ramalingam Gopal ◽  
...  
Keyword(s):  
Energy Storage ◽  
Green Synthesis ◽  
2D Materials ◽  
Synthesis Method ◽  
Energy Storage And Conversion ◽  
Two Dimensional ◽  
Severe Problem ◽  
Energy Conversion And Storage ◽  
Energy Application ◽  
The Impact

: Increasing energy crisis across the globe requires immediate solutions. Two-dimensional (2D) materials are in great significance because of its application in energy storage and conversion devices but the production process significantly impacts the environment thereby posing a severe problem in the field of pollution control. Green synthesis method provides an eminent way of reduction in pollutants. This article reviews the importance of green synthesis in the energy application sector. The focus of 2D materials like graphene, MoS2, VS2 in energy storage and conversion devices are emphasized based on supporting recent reports. The emerging Li-ion batteries are widely reviewed along with their promising alternatives like Zn, Na, Mg batteries and are featured in detail. The impact of green methods in the energy application field are outlined. Moreover, future outlook in the energy sector is envisioned by proposing an increase in 2D elemental materials research.

Two-dimensional topological insulators exfoliated from Na3Bi-like Dirac semimetals

2021 ◽  
Author(s):  
Xiaoqiu Guo ◽  
Ruixin Yu ◽  
Jingwen Jiang ◽  
Zhuang Ma ◽  
Xiuwen Zhang
Keyword(s):  
Physical Properties ◽  
Epitaxial Growth ◽  
Topological Insulators ◽  
2D Materials ◽  
Van Der Waals ◽  
Two Dimensional ◽  
Dirac Semimetals

Topological insulation is widely predicted in two-dimensional (2D) materials realized by epitaxial growth or van der Waals (vdW) exfoliation. Such 2D topological insulators (TI’s) host many interesting physical properties such...

Combined Healing and Doping of Transition Metal Dichalcogenides Through Molecular Functionalization

2021 ◽  
Author(s):  
Sai Manoj Gali ◽  
David Beljonne
Keyword(s):  
Transition Metal ◽  
Charge Transport ◽  
2D Materials ◽  
Transition Metal Dichalcogenides ◽  
Two Dimensional ◽  
Metal Dichalcogenides

Transition Metal Dichalcogenides (TMDCs) are emerging as promising two-dimensional (2D) materials. Yet, TMDCs are prone to inherent defects such as chalcogen vacancies, which are detrimental to charge transport. Passivation of...

Controllable Synthesis of Ultrathin Layered Transition Metallic Hydroxide/Zeolitic Imidazolate Framework-67 Hybrid Nanosheets for High-Performance Supercapacitors

2021 ◽  
Author(s):  
Chunli Liu ◽  
Yang Bai ◽  
Ji Wang ◽  
Ziming Qiu ◽  
Huan Pang
Keyword(s):  
Charge Transfer ◽  
Energy Conversion ◽  
High Performance ◽  
2D Materials ◽  
Two Dimensional ◽  
Controllable Synthesis ◽  
Zeolitic Imidazolate Framework ◽  
Fast Charge ◽  
Energy Conversion And Storage ◽  
And Storage

Two-dimensional (2D) materials with structures having diverse features are promising for application in energy conversion and storage. A stronger layered orientation can guarantee fast charge transfer along the 2D planes...

scholarly journals Recent advances in mode-locked fiber lasers based on two-dimensional materials

Nanophotonics ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 2315-2340 ◽  
Author(s):  
Junli Wang ◽  
Xiaoli Wang ◽  
Jingjing Lei ◽  
Mengyuan Ma ◽  
Cong Wang ◽  
...  
Keyword(s):  
Fiber Lasers ◽  
2D Materials ◽  
Synthesis Methods ◽  
Two Dimensional ◽  
New Materials ◽  
Saturable Absorbers ◽  
Operating Wavelength ◽  
Recent Advances ◽  
Two Dimensional Materials ◽  
Diverse Mode

AbstractDue to the unique properties of two-dimensional (2D) materials, much attention has been paid to the exploration and application of 2D materials. In this review, we focus on the application of 2D materials in mode-locked fiber lasers. We summarize the synthesis methods for 2D materials, fiber integration with 2D materials and 2D materials based saturable absorbers. We discuss the performance of the diverse mode-locked fiber lasers in the typical operating wavelength such as 1, 1.5, 2 and 3 μm. Finally, a summary and outlook of the further applications of the new materials in mode-locked fiber lasers are presented.

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