Graphene's Extraordinary Properties

The graphite layer is functioned to prevent the direct contact of silver layer and manganese oxide.

Diamond is made up of repeating units of carbon atoms joined to four other carbon atoms by a covalent bond

In simple terms, graphene, is a thin layer of pure carbon; it is a single, tightly packed layer of carbon atoms that are bonded together in a hexagonal honeycomb lattice. In more complex terms, it is an allotrope of carbon in the structure of a plane of sp2 bonded atoms with a molecule bond length of 0.142 nanometres. Layers of graphene stacked on top of each other form graphite, with an interplanar spacing of 0.335 nanometres.

Carbon is the fundamental element for everything on Earth. All life on Earth depends on carbon. Carbon has different forms of allotropes including diamond, graphene and charcoal. Carbon is found in position 12, with 4 colvalent electrons. All the allotropes have different properties nd uses due to how the carbon atoms are bonded. Carbon is able to single, double and triple bond with other elements to form complex molecules. Carbon can also use its four electrons to form diamond, where it is strong and stable, or three electrons to form graphite found in pencils, buckyball or all forms of nanocarbon including carbon nanotube.

Stone-Thrower-Wales (STW) defect also referred as pentagon-heptagon-heptagon-pentagon (5-7-7-5) defect is formed by rotating a C-C bond by π/2, which transforms 4 hexagons into 2 pentagons and 2 heptagons as illustrated in Fig.1. Due to hexagonal and symmetric geometry of graphene system, only two types of STW defects are possible, STW1 and STW2 defects that are explained with the help of Fig.1. One of the main feature of graphene with STW defects is that it retains the same number of atoms as the pristine graphene, and also forms without creating any dangling bonds.

Fullerene was first recorded in a Japanese article, Kagaku, written by Eiji Osawa in 1970 which stated the prediction on the existence of C60 compound [1]. In the following year, a conjecture on the stability of C60 was established by Osawa and Yoshida where the aromatic characteristic of C60 was described further. The stability was further better-explained when the Hückel’s calculation method was applied and introduced to the icosahedron structure of C60 by Bochvar and Gal’pern [2]. The prediction of fullerene structure was discussed based on graphite balloon speculation made by David Jones using pseudonym of Daedalus in a journal, The Scientist [3]. This speculation was essentially describing the gas-phase carbon cluster in the form of geodesic cages which is applied to giant fullerenes compound [2].

ABSTRACT: One atom-thick sheet of carbon discovered this century is flaunted not just for its electrical properties but also for its physical strength and flexibility. The bonds between carbon atoms are well known as the strongest in nature, so a perfect sheet of graphene should withstand just about anything, but to use it in real-time applications, we have to understand the useful strength of graphene. So for, researchers have looked extensively at graphene’s electronic properties and tensile strength, nobody, had taken comprehensive measurements of its ability to withstand a compressive load. We find that, counter to standard reasoning, graphene sheets with Stone-Thrower-Wales (STW) defects are able to bear high compressive stress as compared to pristine graphene. We show that this trend can be understood by considering the critical bonds in the seven and five-membered carbon rings which bears the maximum compressive stress. Graphene with STW defects is stronger in compressive strength point of view because they are able to better accommodate these strained rings. Our results provide guidelines for designing graphene with STW defects to obtain maximum compressive strength, so that we can get the benefit of this

Graphene is a hexagonal two-dimensional (2D) monolayer of honeycomb lattice packed carbon structure that was discovered and successfully isolated from bulk graphite just a few years ago [1]. It is a promising candidate in a number of mechanical, thermal and electrical applications [2-6], owing to its outstanding physical properties [2]. In addition to enormous nano-technological applications, graphene also attracts prodigious attention as strengthening element in composites [7-10]. Characterization of the mechanical properties of graphene is essential both from a technological perspective for its reliable applications and from a fundamental interest to understanding its deformation physics [11-13]. In material science, fracture toughness is a property that describes the ability of a material containing a crack to resist fracture, and is one of the most important mechanical properties of any material [14-15]. The useful strength of large area graphene with engineering relevance is usually determined by its fracture toughness, rather than the intrinsic strength

Figure (2) shows the Raman spectrum of prepared activated carbon (AC). The sample shows the characteristic D and G carbon peaks at 1380 cm−1 and 1585 cm−1, respectively. In simple terms, for carbon materials, the D peak intensity correlates with defects in the carbon lattice and is linked to the extent of sp3 hybridization while the G peak arises from the graphitic network and extent of sp2 hybridization. ID/IG = 0 .663, it is smaller than 1, so the structures are considered to show a higher concentration of sp2 hybridization (i.e. extended graphitic character). Moreover, the ratio is close to 1 then the material is considered to have a more amorphous structure with a mixture of sp2 and sp3 hybridization. In this case, where ID/IG is close to 1, the presence of a 2D peak, further associated to interactions between graphene-like planes, suggests a strong graphitic component.

Thin flakes of TMDs can be peeled off from bulk materials using adhesive tape, applied to the substrates and then identified by light interference using similar techniques used to develop graphene. Fig 6c shows a thin monolayer flake peeled off from the bulk material (Fig 6a) mechanically with the tape. Oxide nanosheets as well as other materials can be obtained using this method. Using the mechanical method of exfoliation helps to produce flakes of high purity that can be used for fabrication of individual devices, however, the size and thickness of the flakes produced by this method cannot be controlled. In recent research, lasers have been used to control the thickness of MoS2 flakes by thermal ablation, this method however has a lot of challenges attached to it.

This sheet is the most interesting form of carbon allotropes which promises to be a super-material due to its super properties. Graphene is the mother of other carbon allotropes as shown in Figure ‎1 4 [11]. The sheets of graphene in graphite are held bonding together by van der Waals electrostatic force [12].

Carbon nanotubes get all of their impressive properties from their physical structure. They are hexagons of covalently bonded carbon atoms. A covalent bond is a bond between two non-metals atoms. Two of these atoms are bonded to four others and form another hexagon and these other hexagons exist on all the sides of the first and off of each other. This would look like a sheet of hexagons that could then be "wrapped" into tubes. These tubes can be single walled (SWCNTs), and multi-walled (MWCNTs) depending on the number of layers they have. The carbon atoms in these nanotubes have S2P2 chemical bonds (Zhang 7). This means that the atoms have one

Applications, such as for the transparent conductive electrode, and many other possible applications. Measuring micromechanically peeling layer graphene has been experimentally studied for over 40 years, and transport properties of graphene, the growth in [16among many other potential applications. Graphene is experimental study for over 40 years, and the transport properties of the release layer was measured micromechanically graphene grown in a growth in the copper (Cu) largearea graphene substrate, and a variety of chemical modifi version involves the use of graphene (CMG ), so that the new material,] there are some leads to surge in the number of publications and number, for example, funded by the National Science Foundation recently awarded the United States.

Different combinations of n and p-type doping are used to create electronic components such as transistors, capacitors, and diodes. Silicon became the top semiconductor in the 1960s due to the oxide layer it forms, its ability to perform at higher temperatures, and its availability in nature. When exposed to air, silicon forms a silicon dioxide layer on its surface that serves as an excellent insulator allowing for small interference between different components. Compared to germanium, silicon is able to perform at higher temperatures which becomes important when there are several different components on a chip operating and generating heat. Silicon is also readily available in nature, as it is a main component in sand whereas germanium is difficult to extract in large quantities making it more expensive.

We have now discussed the two extremes in electronic materials; a conductor, and an insulator we will now move to a material that lies in between these two, a semiconductor. The