Carbon- An Introduction
Carbon is found in abundance in living things and materials that are derived from living things. Carbon also plays a vital role in nanotechnology research and nanotechnology applications. Carbon is a non-metallic element present in the cells of organisms. Its atomic number is 6 and atomic weight is 12. The carbon atom has 6 protons and 6 neutrons and combines with other elements to form an array of compounds including carbon-monoxide and carbon-dioxide. Carbon makes about 19 percent of the human body mass and is an important component of fats, proteins, nucleic acids, and carbohydrates. Petroleum, natural gas, coal, oil shale, and all fossil fuels contain carbon as the primary element.
Fullerenes and Nanotechnology
The third allotropic form of the carbon material is called the Fullerenes. These are large carbon molecules arranged in a form different from the shape of diamond or graphite.
Fullerenes are arranged in cylindrical, spherical, or ellipsoid form and are about the size of 1 nanometer. Fullerene was discovered during a laser spectroscopy experiment and is named after Richard Buckminster Fuller.
The buckminsterfullerene (buckyball or C60) is the most common and popular of all fullerenes. It a soccer-ball shaped molecule with 12 pentagons and 20 hexagons. The other well-known buckyballs include C84, C70, and C76.
The family of fullerene carbon molecules possesses some unique properties. A fullerene nanotube is 20-times stronger than steel alloys. Some of the other fullerene applications include being utilized in making fuel cells, computer systems, and sensors. The pharmaceutical industry is exploring the possible uses of fullerenes in drugs in order to control neurological damages caused by diseases such as Lou Gehrig's disease (ALS) and
Alzheimer's condition. Further, pharmaceutical companies are testing the applications of fullerenes in atherosclerosis drugs and in antiviral agents.
According to medical researchers, fullerenes act as sponges soaking up dangerous chemicals from injured brain tissues. These tiny sponges would immobilize dangerous chemicals, which if left untreated, could destroy nerve cells.
Buckyballs when made big become carbon cylinders called as carbon nanotubes. These nanotubes are long and thin and are a different material from graphite or diamond.
A carbon nanotube has certain properties making it potentially useful in a wide spectrum of applications such as optics, nanolithography, nanogears, nanothermometer, nanoelectronics, super capacitors, chemical sensors, batteries, hydrogen storage, and material applications. Carbon nanotubes exhibit unique electrical properties and amazing strength.
There are two types of nanotubes namely: single-walled nanotubes (SWNTs) and multi-walled nanotubes (MWNTs). Majority of the SWNTs measure about 1 nanometer and the tube length is thousand times longer. A SWNT is also called buckytube consisting of a single shell. Nanotubes have physical (electrical conductivity), chemical (thermal conductivity), and mechanical properties making them such an efficient and outstanding material.
The MWNTs are multi-walled nanotubes having 6 to 20 concentric grapheme cylinders.
Carbon nanotubes that are double-walled have higher chemical and thermal stability than that of a single-walled carbon nanotube. MWNT is applied to nanocomposites, gas sensors, and nanoelectrical devices.
Carbon nanotubes literally drive the current advances in nanotechnology. These nanotubes have excellent electronic and mechanical properties. Carbon nanotubes, slightly wider than atoms, offer high-material properties including exceptional thermal and electrical conductivity, toughness, stiffness, and remarkable strength.
A Nano-wire is made from silicon, metal atoms, or other electricity conducting materials.
It is a small wire composed of either semiconductors or metals. Nanowires are also called quantum wire or nanorod since the dimension is 10-9 meters (order of a nanometer).
Nanowires are used to create electrical circuits.
Nanocrytals are developed from semiconductors and metals. Some researchers made nanocrystals of gold, palladium, silver, rhodium, platinum, iridium, and ruthenium. A nanocrystal is about 10 nanometers in diameter. Some of the important applications of nanocrystals include being used as building blocks for composites and strong metals.
Also, the technology has potential impact in lighting, semiconductor materials, flat-screen panels, and high-resolution imaging. Nano-engineered solar cells are considered the future generation of photovoltaics.
Quantum dots are semiconductor nanocrystals measuring about 1-6 nanometers in diameter. A quantum dot is cubic or spherical in shape with thousands of atoms. Potential applications of a quantum dot include: imaging the behavior of organs and cells, monitor organs and cells in healthy and diseased conditions, and monitor the growth of organs and cells.
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