NANOTECHNOLOGY

What is Nanotechnology ?

• Nanotechnology, shortened to “nanotech”, is the study of the controlling of matter on an atomic and molecular scale. Generally nanotechnology deals with structures sized between 1 to 100 nanometer in at least one dimension and involve developing materials or devices within that size.

• A basic definition: Nanotechnology is the engineering of functional systems at the molecular scale. This covers both current work and concepts that are more advanced.

• In its original sense, ‘nanotechnology’ refers to the projected ability to construct items from 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.

How Nanotechnology works ?

The World of

Nanotech Experts sometimes disagree about

what constitutes the nanoscale, but in general, you can think of nanotechnology dealing with anything measuring between 1 and 100 nm. Larger than that is the microscale, and smaller than that is the atomic scale.

Nanotechnology is rapidly becoming an interdisciplinary field. Biologists, chemists, physicists and engineers are all involved in the study of substances at the nanoscale. Dr. Störmer hopes that the different disciplines develop a common language and communicate with one another. Only then, he says, can we effectively teach nanoscience since you can't understand the world of nanotechnology without a solid background in multiple sciences.

An engineer prepares a silicon wafer in an early stage of microchip production.

At the nanoscale, objects are so small that we can't see them -- even with a light microscope. Nanoscientists have to use tools like scanning tunneling

microscopes or atomic force microscopes to observe anything at the nanoscale. Scanning tunneling microscopes use a weak electric current to probe the scanned material. Atomic force microscopes scan surfaces with an incredibly fine tip. Both microscopes send data to a computer,

which can assemble the information and project it graphically onto a monitor 

It’s a small world after all

Synthesis of nanoparticles

• Nanoparticles may be created using several methods. Some of them may occur in nature as well. The methods of creation include attrition and pyrolysis. While some methods are bottoms up, some are called top down. Top down methods involve braking the larger materials into nanoparticles.

Nanoparticle Synthesis

Top-Down via Bottom-Up via

Attrition / Milling Pyrolysis

  Inert gas condensation

  Solvothermal reaction

  Sol-Gel fabrication

  Structured media

Attrition

• Attrition methods include methods by which macro or micro scale particles are ground in a ball mill, a planetary ball mill, or other size reducing mechanism. The resulting particles are air classified to recover nanoparticles.

• Involves mechanical thermal cycles• Yields

– broad size distribution (10-1000 nm)– varied particle shape or geometry– impurities

• Application– Nanocomposites– Nano-grained bulk materials

Bottom up methods• These are further classified according to phases:• Gas (Vapor) Phase Fabrication: Pyrolysis, Inert Gas Condensation

• Liquid Phase Fabrication: Solvothermal Reaction, Sol-gel, Micellar Structured Media

pyrolysis• In pyrolysis, a vaporous precursor (liquid or gas) is forced through a

hole or opening at high pressure and burned. The resulting solid is air classified to recover oxide particles from by-product gases. Pyrolysis often results in aggregates and agglomerates rather than singleton primary particles.

• Instead of gas, thermal plasma can also deliver the energy necessary to cause evaporation of small micrometer size particles. The thermal plasma temperatures are in the order of 10,000 K, so that solid powder easily evaporates. Nanoparticles are formed upon cooling while exiting the plasma region. Examples of plasma used include dc plasma jet, dc arc plasma and radio frequency (RF) induction plasmas.

• For example, silica sand can be vaporized with an arc plasma at atmospheric pressure. The resulting mixture of plasma gas and silica vapour can be rapidly cooled by quenching with oxygen, thus ensuring the quality of the fumed silica produced.

• The advantages of vapor phase pyrolysis include it being a simple process, cost effective, a continuous operation with high yield.

Spray pyrolysis

• The liquid phase fabrication entails a wet chemistry route.• Methods are:• Solvothermal Methods (e.g. hydrothermal)• Sol-Gel Methods• Synthesis in Structure Media (e.g., microemulsion)• Effectiveness of Solvothermal Methods and Sol-gel methods demands a simple

process, low cost, continuous operation and high yield.

Precursors are dissolved in hot solvents (e.g., n-butyl alcohol) and solvent other than water can provide milder and friendlier reaction conditions If the solvent is water then the process is referred to as  hydrothermal method.

Liquid phase synthesis

Solvo-thermal process

Sol-gel process• The sol-gel process is a wet-chemical technique (also known

as chemical solution deposition) widely used recently in the fields of materials science and ceramic engineering.

• Steps include:– Formation of stable sol solution– Gelation via a polycondensation or polyesterification reaction– Gel aging into a solid mass. This causes contraction of the gel

network, also phase transformations and Ostwald ripening.– Drying of the gel to remove liquid phases. This can lead to

fundamental changes in the structure of the gel.– Dehydration at temperatures as high as 8000 degree C, used to

remove M-OH groups for stabilizing the gel, i.e., to protect it from rehydration.

– Densification and decomposition of the gels at high temperatures (T > 8000 degree C), i.e., to collapse the pores in the gel network and to drive out remaining organic contaminants

Sol-gel method

Nanowires and Carbon Nanotubes

Currently, scientists find two nano-size structures of particular interest: nanowires and carbon nanotubes. Nanowires are wires with a very small diameter, sometimes as small as 1 nanometer. Scientists hope to use them to build tiny transistors for computer chips and other electronic devices. In the last couple of years, carbon nanotubes have overshadowed nanowires. We're still learning about these structures, but what we've learned so far is very exciting.

A carbon nanotube is a nano-size cylinder of carbon atoms. Imagine a sheet of carbon atoms, which would look like a sheet of hexagons. If you roll that sheet into a tube, you'd have a carbon nanotube. Carbon nanotube properties depend on how you roll the sheet. In other words, even though all carbon nanotubes are made of carbon, they can be very different from one another based on how you align the individual atoms.

What's the difference between graphite and diamonds?

Both materials are made of carbon, but both have vastly different properties. Graphite is soft; diamonds are hard.

Graphite conducts electricity, but diamonds are insulators and can't conduct electricity. Graphite is opaque; diamonds are usually transparent. Graphite and diamonds have these

properties because of the way the carbon atoms bond together at the nanoscale.

GRAPHITE DIAMONDS

VS.

Nanomachines• If molecular models really moved while

revealed in the animations underneath, that they couldn't work. Do not pin the consequence on your simulation or perhaps the look, though. The issue is the regular way to render video clip support frames makes a stroboscopic impression regarding jerky movement. Atoms generally vibrate countless times for each body, yet regular frames catch the positioning of each and every atom with a one quick, just as if noticed with the display of your stroboscope. That creates the actual optical illusion which the atoms most vibrate at the shape charge, that is too towards the regularity in the machine's transferring components. This provides you with this misconception how the device parts are going on just about arctic pace, just like this pace associated with appear. From that will pace, even though your machine proved helpful, chaffing would be intolerable.

MarkIII(k) Planetary Gear

And here is your SRG-Ic, virtually any parallel-shaft swiftness reducer merchandise put together by Quantities Sims. This been found designed and in addition simulated thoroughly applying NanoEngineer-1. This specific assemblage ıs known for a pinion physical objects, some form of effect objects, as well as a silicon carbide defending having a number of utilized bushings

SRG-Ic

SRG-II

This is the SRG-II. It had been patterned besides simulated just making use of NanoEngineer-1 (Alpha dog 6). The goal of the actual SRG-II appeared becoming to produce a effective nanoscale items which includes any kind of property along with long connection shafts.

SRG-III

This is sometimes a SRG-III. That been found modeled plus simulated entirely implementing NanoEngineer-1. A brand new crossbreed while using SRG-I together with SRG-II, oahu is the 2nd molecular items coach previously meant. Acquiring 15, 342 atoms, your SRG-III will be the upcoming biggest nanomechanical system really patterned inside atomic aspect.

Nanotechnology in Medicine 

• – Researchers in medicines are developing customized nanoparticles as the size of molecules that can directly deliver drugs to the diseased cells in the body. When this method is perfected than it will reduce the damaged treatment such as chemotherapy does to the patient’s healthy cells.

Nanotechnology in Electronics 

• Nanotechnology increases the capabilities of electronics devices while reducing their weight and power consumption.

• Improves display screens on electronics devices.

• Increasing the density of memory chips

• Reducing the size of transistors used in integrated circuits

Integrated circuits