Page 1 :
Definitions of nanotechnology, “Nanotechnology is the creation of functional materials, devices and systems through control, of matter on the nanometer length scale (1-100 nanometers), and exploitation of novel, phenomena and properties (physical, chemical, biological, mechanical, electrical...) at that, length scale.”, Definitions of nanomaterials, Nanomaterials describe, in principle, materials of which a single unit is sized (in at least one, dimension) between 1 to 100 nanometres, zero-dimensional (0D) nanomaterials:, In zero-dimensional (0D) nanomaterials all the dimensions are measured within the nanoscale, (no dimensions are larger than 100 nm). Most commonly, 0D nanomaterials are nanoparticles., one-dimensional nanomaterials (1D ) :, In one-dimensional nanomaterials (1D), one dimension is outside the nanoscale. This class, includes nanotubes, nanorods, and nanowires., two-dimensional nanomaterials (2D):, In two-dimensional nanomaterials (2D), two dimensions are outside the nanoscale. This class, exhibits plate-like shapes and includes graphene, nanofilms, nanolayers, and nanocoatings., Three-dimensional nanomaterials :Three-dimensional nanomaterials (3D) are materials that, are not confined to the nanoscale in any dimension., Nanotechnology is helping to considerably improve, even revolutionize, many technology and, industry sectors: information technology, homeland security, medicine, transportation, energy,, food safety, and environmental science, among many others. Described below is a sampling of, the rapidly growing list of benefits and applications of nanotechnology., Many benefits of nanotechnology depend on the fact that it is possible to tailor the structures, of materials at extremely small scales to achieve specific properties, thus greatly extending the, materials science toolkit. Using nanotechnology, materials can effectively be made stronger,, lighter, more durable, more reactive, more sieve-like, or better electrical conductors, among, many other characters., Applications of nanotechnology/nanomaterials., 1. Electronic and Information technology

Page 2 :
Nanotechnology has greatly contributed to major advances in computing and electronics,, leading to faster, smaller, and more portable systems that can manage and store larger and, larger amounts of information. These continuously evolving applications include:, 2. Medical and healthcare, Nanotechnology is already broadening the medical tools, knowledge, and therapies currently, available to clinicians. Nanomedicine, the application of nanotechnology in medicine, draws, on the natural scale of biological phenomena to produce precise solutions for disease, prevention, diagnosis, and treatment. Below are some examples of recent advances in this area,, for example application of gold nanoparticles as probes for the detection of targeted sequences, of nucleic acids, and gold nanoparticles are also being clinically investigated as potential, treatments for cancer and other diseases., 3. Energy, Nanotechnology is finding application in traditional energy sources and is greatly enhancing, alternative energy approaches to help meet the world’s increasing energy demands. Many, scientists are looking into ways to develop clean, affordable, and renewable energy sources,, along with means to reduce energy consumption and lessen toxicity burdens on the, environment:, Nanotechnology is improving the efficiency of fuel production from raw petroleum materials, through better catalysis. It is also enabling reduced fuel consumption in vehicles and power, plants through higher-efficiency combustion and decreased friction., Nanotechnology can be incorporated into solar panels to convert sunlight to electricity more, efficiently, promising inexpensive solar power in the future., 4. Environmental remediation, In addition to the ways that nanotechnology can help improve energy efficiency (see the section, above), there are also many ways that it can help detect and clean up environmental, contaminants:, •, , Nanotechnology could help meet the need for affordable, clean drinking water through, rapid, low-cost detection and treatment of impurities in water.

Page 3 :
•, , Engineers have developed a thin film membrane with nanopores for energy-efficient, desalination. This molybdenum disulphide (MoS2) membrane filtered two to five times, more water than current conventional filters., , •, , Nanoparticles are being developed to clean industrial water pollutants in ground water, through chemical reactions that render the pollutants harmless. This process would cost, less than methods that require pumping the water out of the ground for treatment., , •, , Properties of Nanomaterials, Nanomaterials have the structural features in between of those of atoms and the bulk materials., While most microstructured materials have similar properties to the corresponding bulk, Materials, the properties of materials with nanometer dimensions are significantly different, from those of atoms and bulks materials. This is mainly due to the nanometer size of the, materials which render them: (i) large fraction of surface atoms; (ii) high surface energy; (iii), spatial confinement; (iv) reduced imperfections, which do not exist in the corresponding bulk, materials. Due to their small dimensions, nanomaterials have extremely large surface area to, volume ratio, which makes a large to be the surface or interfacial atoms, resulting in more, “surface” dependent material properties. Especially when the sizes of nanomaterials are, comparable to length, the entire material will be affected by the surface properties of, nanomaterials. This in turn may enhance or modify the properties of the bulk materials. For

Page 4 :
example, metallic nanoparticles can be used as very active catalysts. Chemical sensors from, nanoparticles and nanowires enhanced the sensitivity and sensor selectivity. The nanometer, feature sizes of nanomaterials also have spatial confinement effect on the materials, which, bring the quantum effects., Optical Properties., 1) The properties like colour and transparency are considered as optical properties. These, properties are observed to change at nanoscale level. For example bulk gold appear yellow in, colour while in nanosize gold appear red in colour., 2.) Bulk silicon appears grey in colour while nanosized silicon appears red in colour. 3.) Zinc, oxide, which at bulk scale blocks ultraviolet light and scatters visible light and gives white, appearance. While nanoscale zinc oxide is very small in particle size compared with, wavelength of visible light and it does not scatters it. Thus it appears transparent., Reason for change in optical properties in nanoscale: The main reason for change in optical, properties at nanoscale level is that nanoparticles are so small that electrons in them are not as, much free to move as in case of bulk material. Due to this restricted movement of electrons,, nanoparticles react differently with light as compared to bulk material., Electrical properties, The properties like conductivity or resistivity are come under category of electrical properties., These properties are observed to change at nanoscale level like optical properties. The, examples of the change in electrical properties in nanomaterials are:, Conductivity of a bulk or large material does not depend upon dimensions like diameter or area, of cross section and twist in the conducting wire etc. However it is found that in case of carbon, nanotubes conductivity changes with change in area of cross section., Magnetic Properties, Magnetic nanoparticles are those which can be affected using magnetic field. These particles, usually contain magnetic elements like iron, nickel, cobalt etc. Magnetic nanoparticles show a, variety of unusual magnetic behaviour when compared to the bulk materials, mostly due to

Page 5 :
surface or interface effects, including symmetry breaking, electronic environment or charge, transfer and magnetic interactions., Chemical properties of nanomaterials, Chemical properties of nanomaterials also change at nanoscale. As the percentage of surface, atoms in nanoparticles is large compared with bulk objects, therefore reactivities of, nanomaterials are more than bulk materials. The following are the some of the chemical, properties are:, 1.) The superiority of surface is a major reason for the change in behaviour of materials at the, nanoscale. As up to half of all the atoms in nanoparticles are surface atoms, properties such as, electrical transport are no longer determined by solid-state bulk phenomenon., 2.) The atoms in nanomaterials have a higher average energy than atoms in longer structures,, because of the larger proportion of surface atoms. For example, catalytic materials have a, greater chemical activity per atom of exposed surface as the catalyst is reduced in size at the, nanoscale., , Carbon nanotubes (CNTs), Carbon nanotubes (CNTs) are an allotrope ofcarbon. They take the form of, cylindrical carbonmolecules and have novel properties that make them potentially useful in a, wide variety of applications in nanotechnology, electronics, optics and other fields of materials, science., Carbon Nanotubes Properties, •, , CNTs have high thermal conductivity, , •, , CNTs have high electrical conductivity, , •, , CNTs aspect ratio, , •, , CNTs are very elastic ~18% elongation to failure, , •, , CNTs have very high tensile strength, , •, , CNTs are highly flexible — can be bent considerably without damage, , •, , CNTs have a low thermal expansion coefficient, , •, , CNTs are good electron field emitters

Page 6 :
Synthetic methods, ➢ The carbon arc discharge method, ➢ Chemical Vapor Deposition (CVD), ➢ Ball milling and subsequent annealing, ➢ Liquid electrolysis method, , Applications of Carbon nanotubes (CNTs), Their unique composition, geometry, and properties enable numerous potential carbon, nanotubes applications. Getting costs down to commercially viable levels has proven, challenging but increasing scale is happening., Energy Storage, Molecular Electronics, Thermal Materials, Structural Materials, Electrical Conductivity, FabricsAndFibers, CatalystSupports, Biomedical, , Nanowires, Nanowires are simply very tiny wires having nano-scale diameter. They are composed of, metals such as silver, gold or iron. which are used in nanotechnologies for the manufacturing, of nanomachines., Types of Nanowires, Many different types of nanowires exist, including superconducting nanowires (e.g. YBCO),, metallic nanowires (e.g. Ni, Pt, Au), semiconducting nanowires (e.g. silicon nanowires, (SiNWs), InP, GaN) insulating nanowires (e.g. SiO2, TiO2). And Molecular nanowires are, composed of repeating molecular units either organic (e.g. DNA)

Page 7 :
Vapour–liquid–solid method of nanowire synthesis of crystalline nanowires:, The vapour–liquid–solid method (VLS) is a mechanism for the growth of one-dimensional, structures, such as nanowires, from chemical vapor deposition. The growth of a crystal through, direct adsorption of a gas phase on to a solid surface is generally very slow. The VLS, mechanism circumvents this by introducing a catalytic liquid alloy phase which can rapidly, adsorb a vapor to supersaturation levels, and from which crystal growth can subsequently, occur from nucleated seeds at the liquid–solid interface. The physical characteristics of, nanowires grown in this manner depend, in a controllable way, upon the size and physical, properties of the liquid alloy., , Applications of nanowires, The most obvious use for nanowires is in electronics. Some nanowires are very good, conductors or semiconductors, and their miniscule size means that manufacturers could fit, millions more transistors on a single microprocessor. As a result, computer speed would, increase dramatically., Nanowires in medicine, nanowires are used to coat titanium implants. Doctors have discovered that muscle tissue, sometimes doesn't adhere well to titanium, but when coated with the nanowires, the tissue can, anchor itself to the implant, reducing the risk of implant failure.