Graphene, which discover by the Geim and Novoselov 1,is a material that is composed of a single layer of sp2 hybridized pure carbon atoms arranged in a regular hexagonal honeycomb pattern as shown in Figure 1. This material has unique mechanical, electrical, chemical and thermal properties which stimulate a huge research interest.2,3 Graphene also can be thought as a building block for the formation of fullerenes, carbon fibers, carbon nanotubes and graphite.1
Fig. 1. 2D Structure of single-layer graphene
As we stated earlier, graphene consists of the lattice of sp2 hybridized carbon atoms. In carbon atom, there are three orbitals namely 2s, 2px and 2py which are responsible for the formation of covalent sigma bond between the other adjacent carbon atoms to form the 2D structure of graphene. However, the other p orbital, 2pz, which is out of the plane of the structure forms the pi bonds. The energy of pi bonding orbitals in the graphene is close to the Fermi energy level. Therefore, it provides delocalized states which are responsible for the electrical conductivity of graphene.4,5 However, for the few layers of graphene the orientation of these pi orbitals changes that is why the electronic properties of graphene depend strongly on the number of graphene layers. Hence, only single-layer and bilayer graphene are zero band gap semiconductors which means there is no energy gap between the valence band and the conduction band. On the other hand, in the case of few-layer graphene, the conduction and valence bands start to overlap. Because of this kind of properties, graphene exhibits unique electrical properties such as having high carrier mobility, a stable 2D crystal structure and ability to perform ballistic transport at room temperature.6,7
Beside the electrical properties, single layer graphene has other properties differ from a few layered graphene. For example,
Due to the varied properties and the scope of application which the CNTs possess, it is of paramount importance that CNTs are produced sufficiently at a competitive cost with the existing technology. The research over two decades, since the discovery of CNTs at Iijima’s Laboratory in 1991, has not helped in reduction of cost or production of CNTs of well-defined properties on a massive scale (Kumar, n.d.). This is mainly because of the complexity in the growth mechanism of CNTs. Extra ordinary properties and applications cannot be unleashed without the fundamental understanding of the growth mechanism of Carbon Nanotubes (Kumar, n.d.). There are several methods to produce Carbon Nanotubes in a laboratory setup. Some of widely used techniques include
...gnetic. This new magnetic state stems from the fact that the spins are interacting by the double exchange interaction. Subsequently the insulating state changes to semiconductor. Furthermore, the general concept is that ferromagnetic materials favours metalicity.
Thin = less than about one micron (10,000 Angstroms - 1000 nm) Film = layer of material on a substrate.
In chemistry, out of all the elements on the periodic table, there are a few that stand out because of certain characteristics, Gallium is one of these elements. On the periodic table, Gallium has the symbol Ga and atomic number 31. Gallium is a metal that has uses in such things as, medical, industrial, and everyday life.
Fullerene can be considered as radical scavengers (a chemical substance added to a mixture in order to remove or de-activate impurities and unwanted reaction
Jared Diamond on Advancement in Technology and Warfare Many people assumed that all technology advanced at the same pace and only affect a very small part of our lives. I’ve always believed that most our history is based on technological advancement. Specifically, technological advancement in warfare. Jared Diamond observed why technological advancement happen, how that affect warfare, and in return, the real world.
Answer: It is the difference between interfacial conduction band edge (Ec) and the Fermi level (Ef). From the figure below we get a better idea of the barrier height which is given by ΦB(PhiB).
Graphene has received great mass media coverage since Geim and Novoselov published their foundlings about monocrystalline graphitic films in 2004, which won them the Nobel Prize in Physics in 2010. (Novoselov et al, 2004) It has been described as the wonder substance or super material by the mass media, not only because it is the thinnest material ever known and the strongest ever measured, but also due to its excellent electrical, thermal, mechanical, electronic, and optical properties. It has high specific surface area, high chemical stability, high optical transmittance, high elasticity, high porosity, tunable band gap, and ease of chemical functionalization which helps in tuning its properties (Geim et al, 2007) Moreover, graphene has a multitude of amazing properties such as half-integer room-temperature quantum Hall effect (Novoselov et al, 2007), long-range ballistic transport with almost ten times greater electron mobility than that of silicon, and availability of charge carriers that behave as massless relativistic quasi particle, known as Dirac fermions. (Geim et al, 2007) The outstanding electrical conductivity and the transparency and flexibility of graphene-based material have led to research and development of some future technologies, such as flexible and wearable electronics. In addition, graphene can also be used for efficient energy storage materials, polymer composites, and transparent electrodes. (Geim et al, 2007) This paper presents a
Diamonds earned its original name from the Greek word “adamas” that means "invisible" (Oldershaw, 2005) because it is considered as the most hard mineral that is cannot scratched in with other minerals. In addition, the diamond is a unique jewel of other gems as formed from a single chemical that is carbon. Furthermore, it is doubtful that diamonds actually contain chemicals that are similar to those of Graphite and charcoal. The difference is only in the process of formation where diamonds are crystallized in the form of a cube under the pressure of large earth pressure and high temperatures up to thousands of degrees Celsius. Thus, the bonds of the carbon atoms in diamond are very strong and uniform to produce crystals that ...
Fullerenes are accepted as the fourth for of solid carbon after amorphous, graphite and diamond forms. Fullerene chemistry has provided a new dimension of aromatic and a new platform for discussion of mathematical techniques pertinent to large cages. They are basically, large carbon cage molecules. These fullerenes have attracted great interest a large number of physical and chemical properties. These properties of nanostructures strongly depend on this size, shape and chemical compositions. This property leads to very interesting and recent applications in medicinal chemistry, material science and nanotechnology. Functionalization, intercalation and doping by the addition of electron acceptors or donors are the way of modifying the properties of these nanostructures. Among these nanostructures carbon based nanomaterials such as nanotubes, nanocages, nanoshells,
Diamond is made up of carbon. Another form of pure carbon is graphite. Graphite is the stable form of carbon, found at the earth’s surface. Despite the fact that they have identical chemical composition, the two minerals are drastically different. Diamond is the hardest known substance and is usually light colored and transparent, while graphite is greasy, easily powdered, and very dark in color. Diamond is the hardest gem on Mohs’ hardness scale and graphite is the softest. Diamond is very hard because of its dense packing and interlocking atomic arrangement. Graphite, on the other hand, although it is the same element, is more loosely packed and has a six-sided, layered configuration, which makes it soft (Pough, 1991). The differences between graphite and diamonds are accounted for by the conditions in which they are created.
Grundmann, Marius. Physics of Semiconductors: An Introduction Including Devices and Nanophysics. New York: Springer, 2006. Print.
Steel: (for all intents and purposes) was invented in 1855 by Henry Bessemer(Mary Bellis). Science the amazing innovation that has changed the world incredible things have been made from the material from bridged cables and cross beams to arresting wires on aircraft carriers that stop monumental force and speed. It is truly an amazing martial, but eventually it snaps, breaks or tears due to the separation of the molecules. Also steel is not the most flexible material there is which may sound good for what it is used for, construction. You wouldn’t want the floor to shift from under but, what about in areas that have a consent threat of earthquakes having a material that is rigid when needed and flexible when needed would be an invaluable asset to construction companies in many countries. Also at $600-$900 per ton(Platts Mcgraw hill financial) it isn’t the most inexpensive material that could be chosen. Chemically is there a better material that could be used in the place of steel that is stronger more flexible and can be produced for a cheaper price than the normal steel that we use today? First, the choice of spider silk seems like a great choice. Mother nature seems to be the greatest designer of all made of different sections of proteins of extremely ridged and at the same time extremely elastic strings of proteins, that when braided together are 5 times stronger than steel and relatively free to produce as long as the spiders are kept healthy. What makes the proteins so strong? They are linked together almost like thousands of Lego’s linked together which by its self does not sound very strong, but just take 3 and pull length wise and try to pull them apart, it's almost impossible. The same concept is used in the spider's silk...
I have chosen nanotechnology as my topic area of choice from the food innovation module.
Graphite is another form of carbon. It occurs as a mineral in nature, but it can be made artificially from amorphous carbon. One of the main uses for graphite is for its lubricating qualities. Another is for the "lead" in pencils. Graphite is used as a heat resistant material and an electricity conductor. It is also used in nuclear reactors as a lubricator (Kinoshita 119-127).