INTRODUCTION TO NANOTECHNOLOGY

INTRODUCTION TO NANOTECHNOLOGY Dr. Mrs. M. H. Dhend Electrical Engg. Department AISSMS COE Pune

Courtesy Office of Basic Energy Sciences,Office of Science, U.S. Department of Energy Dr. Mrs. Mangal Dhend

Nanotechnology may be able to create many new materials and devices with a vast range of applications, such as in medicine, electronics, biomaterials and energy production. • On the other hand, nanotechnology raises many of the same issues as any new technology, including concerns about the toxicity and environmental impact of nano materials, and their potential effects on global economics. • Another important criteria for the definition is the requirement that the nano-structure is man-made. Otherwise you would have to include every naturally formed bio molecule and material particle, in effect redefining much of chemistry and molecular biology as 'nanotechnology.' • The most important requirement for the nanotechnology definition is that the nano-structure has special properties that are exclusively due to its nano scale proportions. Dr. Mrs. Mangal Dhend

A good definition that is practical and unconstrained by any arbitrary size limitations is: • The design, characterization, production, and application of structures, devices, and systems by controlled manipulation of size and shape at the nanometer scale (atomic, molecular, and macromolecular scale) that produces structures, devices, and systems with at least one novel/superior characteristic or property. Dr. Mrs. Mangal Dhend

NANO TECHNOLOGY Nanotechnology is the engineering of functional systems at themolecular scale. This covers both current work and concepts that are more advanced. In its original sense, 'nanotechnology' refers to the projected ability to construct itemsfrom the bottom up, using techniques and tools being developed today to make complete, high performance products. Nanotechnology, in its traditional sense, means building things from the bottom up, with atomic precision. Nanotechnology may be able Nanotechnology (sometimes shortened to "nanotech") is the manipulation of matter on an atomic and molecular scale. Generally, nanotechnology works with materials, devices, and other structures with at least one dimension sized from 1 to 100 nanometers.

The element carbon • Carbon has four electrons in its valence shell (outer • shell). Since this energy shell can hold eight electrons, each carbon atom can share electrons with up to four different atoms. • Carbon can combine with other elements as well as with itself. This allows carbon to form many different compounds of varying size and shape. • Carbon alone forms the familiar substances graphite and diamond. Both are made only of carbon atoms. Graphite is very soft and slippery. Diamond is the hardest substance known to man. If both are made only of carbon what gives them different properties? Dr. Mrs. Mangal Dhend

Dr. Mrs. Mangal Dhend

There are strong covalent bonds between carbon atoms in each layer. But, only weak forces exist between layers. This allows layers of carbon to slide over each other in graphite. • On the other hand, in diamond each carbon atom is the same distance to each of its neighboring carbon atoms. In this rigid network atoms cannot move. This explains why diamonds are so hard and have such a high melting point. Dr. Mrs. Mangal Dhend

For 3D structures and images of carbon molecules (graphite, diamond and fullerene) Dr. Mrs. Mangal Dhend

What are Carbon Nano tubes? • A significant nano particle discovery that came to light in 1991 was carbon nano tubes. • Where buckyballs are round, nanotubes are cylinders that haven’t folded around to create a sphere. • Carbon nanotubes are composed of carbon atoms linked in hexagonal shapes, with each carbon atom covalently bonded to three other carbon atoms. • Carbon nanotubes have diameters as small as 1 nm and lengths up to several centimeters. • Although, like buckyballs, carbon nanotubes are strong, they are not brittle. They can be bent, and when released, they will spring back to their original shape. Dr. Mrs. Mangal Dhend

Another type of nano tube has closed ends, formed by some of the carbon atoms combining into pentagons on the end of the nano tube, as shown in the following figure. A carbon nanotube with closed ends. Dr. Mrs. Mangal Dhend

Carbon nanotubes can occur as multiple concentric cylinders of carbon atoms, called multi-walled carbon nanotubes (MWCTs) and shown in the following figure. • Logically enough, carbon nanotubes that have only one cylinder are called single-walled carbon nanotubes (SWCTs). • Both MWCT and SWCT are used to strengthen composite materials. Dr. Mrs. Mangal Dhend

Electrical properties of nanotubes The electrical properties of carbon nanotubes depend on how the hexagons are orientated along the axis of the tube. The following figure shows the three orientations that are possible: armchair, zigzag, and chiral. Dr. Mrs. Mangal Dhend

Carbon nanotubes with the hexagons orientated in the configuration labeled armchair (hexagons are lined up parallel to the axis of the nanotube) have electrical properties similar to metals. • When you apply a voltage between two ends of an armchair nanotube, a current will flow. • An armchair carbon nanotube is, in fact, a better conductor than the copper normally used in electrical wire, or any other metal. Dr. Mrs. Mangal Dhend

Applications of Nanotubes – • There are many applications of nanotubes that have the potential to change the face of humankind. • Nanotechnology could change everything and the purpose of nanotubes is change the way we treat diseases to how we purchase our everyday essentials like food. • While most applications for nanotubes are still quite futuristic, the progress in this relatively young science has been astonishing. • The 1990s and the early part of the 21st century has proven to be a continuous developmental promise for the applications of carbon nanotubes. Dr. Mrs. Mangal Dhend

Nanotubes are a round connection of atoms that create one of three distinctive patterns, capped at the ends by fullerene molecules. • These tubes can be manipulated with care to conduct electricity and to withstand very great stresses. • The nanotubes are stronger than steel and can be directed to take on specific human cell or be used to create special coatings for the quantum wires that can be used for a host of potential Dr. Mrs. Mangal Dhend

The properties of nano tubes have caused researchers and companies to consider using them in several fields. • For example, because carbon nano tubes have the highest strength-to-weight ratio of any known material, researchers at NASA are combining carbon nano tubes with other materials into composites that can be used to build light weight spacecraft. Dr. Mrs. Mangal Dhend

Carbon nanotubes are being developed to clean up oil spills. Researchers have found that adding boron atoms during the growth of carbon nanotubes causes the nanotubes to grow in a sponge like material that can absorb many times it's weight in oil. Lightweight windmill blades made with an epoxy containing carbon nano The strength and low weight provided by the use of nanotube filled epoxy allows longer windmill blades to be used. This increases the amount of electricity generated by each windmill . Carbon have developed a sensor that uses nanotubes and gold nanoparticles to detect proteins indicative of oral cancer. Tests have shown this sensor to be accurate in detecting oral cancer and provides results in less than an hour. Dr. Mrs. Mangal Dhend

Longer lasting concrete, researchers have found that carbon nanotubes can fill the voids that occur in conventional concrete. Because it's these voids that allow water to penetrate into concrete, resulting in the formation of cracks; including nanotubes in the mixstops the cracks from forming. Carbon nanotubes that perform as a catalyst, without using expensive platinum which most catalysts are based upon. Researchers have found that incorporating nitrogen and iron atoms into the carbon lattice of nanotubes result in nanotubes with catalytic properties. Researchers are developing materials, such as a carbon nanotube based composite developed by NASA that bends with when a voltage is applied, that will need only an electrical voltage to change the shape (morphing) of aircraft wings and other structures. . Dr. Mrs. Mangal Dhend

Diamond shaped and graphite Dr. Mrs. Mangal Dhend

Nanomaterials and Assemblies Will provide an overview of nanomaterials and nanoscale synthesis techiques Self-assembled monolayers Block copolymers Fullerenes and nanotubes Dr. Mrs. Mangal Dhend

The Simple Cubic Lattice Dr. Mrs. Mangal Dhend

The CsCl Structure Dr. Mrs. Mangal Dhend

The Body Centered Cubic Structure Dr. Mrs. Mangal Dhend

The Face Centered Cubic Latteric Dr. Mrs. Mangal Dhend

The NaCl Structure Dr. Mrs. Mangal Dhend

The Simple Hexagonal Lattice Dr. Mrs. Mangal Dhend

Carbon Structures Hexagonal Graphite Crystal Structure: sp2 bonding Dr. Mrs. Mangal Dhend

Diamond Crystal Structure: sp3 bonding Dr. Mrs. Mangal Dhend

INTRODUCTION TO NANOTECHNOLOGY