{"id":20,"date":"2018-12-06T04:55:19","date_gmt":"2018-12-06T04:55:19","guid":{"rendered":"http:\/\/msp08.epgpbooks.inflibnet.ac.in\/?post_type=chapter&p=20"},"modified":"2018-12-06T05:12:07","modified_gmt":"2018-12-06T05:12:07","slug":"introduction-nanoscience-and-nanotechnology","status":"publish","type":"chapter","link":"https:\/\/ebooks.inflibnet.ac.in\/msp08\/chapter\/introduction-nanoscience-and-nanotechnology\/","title":{"rendered":"Introduction: Nanoscience and Nanotechnology"},"content":{"raw":"
\r\n
\"epgp<\/a>\r\n<\/span><\/div>\r\n\u00a0 <\/strong>\r\n\r\n \r\n\r\n \r\n\r\n \r\n\r\nIntroduction:<\/strong>\r\n\r\n \r\n

Nanoscience and nanotechnology are being envisaged as the science and technology of the future. They are being expected to transform our understanding of almost every natural phenomenon. Nanotechnology is predicted to revolutionize every aspect of human life. However, the technology itself is in its nascent stage and needs comprehensive understanding of the various aspects of objects at which it is applicable. This chapter provides the essential insights into the dimensions which are relevant to this technology.<\/p>\r\n \r\n\r\n1. Length, energy and time scales<\/strong>\r\n\r\n \r\n

This module presents an introduction about nanoscience, nanotechnologies, and nanomaterials. Historical account of the events leading to the formal introduction of the field is also given.<\/p>\r\n \r\n\r\nNanoscience<\/strong>\r\n\r\n \r\n

Nanoscience is the study of processes and manipulation of materials at atomic or molecular scale, such that the properties vary considerably than at larger scales, i.e., bulk materials.<\/p>\r\n\"\"\r\n\r\n \r\n

Bulk and micron-sized materials (such as a sand granule) demonstrate continuous (macroscopic) physical properties. However, as the size of the materials is decreased down to the nanoscale, classical physics\u00a0fails to explain their behaviors or properties (e.g., energy, momentum, etc.), and quantum mechanics needs to be applied to describe them. For example, depending upon the particle size, gold demonstrates very different properties (optical, electrical, mechanical, etc.) at <\/span>nanoscale (<\/span>Figure 1<\/strong>).<\/span><\/p>\r\n\r\n<\/div>\r\n

\r\n\r\n\"\"\r\n\r\n \r\n

Figure 1 Different sized gold particles produce different colors at nanoscale.<\/strong><\/p>\r\n \r\n

Nanotechnologies include \u201cnanoscale designing, characterizing, and producing structures, devices and systems by controlling shape and size for their applications in various fields\u201d.<\/p>\r\n \r\n

Analogous to several other disciplines, nanotechnology was in use several centuries before any formal definition of the field. For example, nanotechnology was widely used in steel and painting industries. Early contributions came from James Clark Maxwell and Richard Adolf Zsigmondy. Zsigmondy investigated colloidal solutions including sols of gold as well as other nanomaterials. Irvin Langmuir and Katherine B. Blodgett contributed significantly to the field in first half of twentieth century.<\/p>\r\n \r\n

American physicist Richard Feynman is credited with the first modern systematic discussion and formal announcement of nanotechnology as an important field of scientific endeavor. In this regard, his famous lecture \u201cThere\u2019s Plenty of Room at the Bottom\u201d given in 1959 has been adapted in various discussions of the field. Though he did not coin the term \u2018nanotechnology\u2019, he emphasized the significance of manipulation of matter at very small scale such that these studies will allow the understanding of processes occurring in complex situations. He talked about size dependent behavior of various phenomena and proposed various challenges such as creating a nanomotor, embedding whole Encyclopedia Britannica on a pin\u2019s head.<\/p>\r\n \r\n

Norio Taniguchi, Japanese scientist, mentioned the term \u2018nanotechnology\u2019 for the first time in 1974 in his paper on synthesis technology to create objects and features of nanometer dimension. He writes:<\/p>\r\n \r\n

\u201c<\/span>In the processing of materials, the smallest bit size of stock removal, accretion or flow of materials is<\/em> probably of one atom or one molecule, namely 0.1\u20130.2 nm in length. Therefore, the expected limit size of fineness would be of the order of 1 nm.\u2026 Nano-Technology mainly consists of the processing \u2026\u00a0<\/em>separation, consolidation and deformation of materials by one atom or one molecule<\/em>\u201d.<\/span><\/p>\r\n \r\n

K. Eric Drexler, an American engineer, is often cited with the developer of molecular nanotechnology which led to the development of nanosystem machinery.<\/span><\/p>\r\n \r\n

The respective discoveries of scanning tunneling and atomic force microscopes in <\/span>1980s are considered <\/span>milestone for the development of nanotechnology as a filed. These microscopes allowed atomic level imaging of materials which is crucial for manipulating matter at atomic\/molecular scales. The parallel advancements in computer technology facilitated large scale simulations and analyses of materials by supercomputers, thereby providing significant insights into the structure as well as <\/span>properties of the materials. The simultaneous modeling, visualizing, as well as manipulation activities, greatly stimulated research investigations in the twentieth century.<\/span><\/p>\r\n \r\n

One such effort was made by IBM wherein the physicists performed atomic scale manipulation of xenon atoms to produce the pattern \u201cIBM\u201d in 1990 (see <\/span>Figure 2<\/strong>). The discovery of new carbon structure, buckyball made up of 60 carbon atoms, further increased the interest in the field. This propelled the investigation to discover other nanostructures made up of carbon as well as other materials. The 1991 finding of carbon nanotubes has been instrumental in enthusing research activities in the field of nanoscience and nanotechnology; consequently, numerous nanotechnologies have been unearthed. Carbon nanotubes are one of the most studied materials owing to its amazing properties such as it gives ~100 times <\/span>strength than steel at 1\/6th of the weight. Similarly, novel structures including Quantum dots have been produced which demonstrate properties intermediary to the bulk and single molecular structures.<\/span><\/p>\r\n\r\n<\/div>\r\n

\r\n\r\n\"\"\r\n\r\n \r\n

Figure 2 Demonstration of manipulating atoms with atomic-scale precision with Xenon atoms by IBM.<\/strong><\/p>\r\n \r\n

The astounding physical, chemical as well as mechanical behaviors of nanomaterials, such as large surface area, tiny size, etc.; offer extensive applications in numerous fields including electronics, optoelectronics, etc. Presently, molecular electronics is being proposed as <\/span>new technological breakthrough. As silicon IC technology is approaching its physical limits, nanotechnology is expected to drive the future generation electronics. If devices can be made from a small cluster of atoms or molecules, computer chips can be fabricated to house 10 times more transistors than possible by the present technology.<\/span><\/p>\r\n\r\n<\/div>\r\n

\r\n\r\n \r\n\r\n1.1 Nanometre Scale<\/strong>\r\n\r\n \r\n

Conventionally, nanoscale has been defined as 1-100 nm. A nanometer is one billionth part of one meter. The minimum size is set to 1 nm, thus a single atom or very small clusters of atoms cannot be considered as nanoparticles. Consequently nanoscience and nanotechnology involve a cluster of atoms at least 1 nm in size. However, the necessary condition for denoting clusters of atoms as nanomaterials is the onset of a quantum phenomenon instead of the actual dimension at which the effect occurs. Furthermore, above nanoscale, the properties of a material result from bulk or volume effects, namely the type of the atoms present, type of bonding existing between them, and the stoichiometry. Below this point, the properties of the materials change and even though the type of atoms and their organizational orientation are still important, surface area effects begin to dominate. The surface area effects include the size as well as the shape of the object.<\/p>\r\n \r\n

Therefore, nanoscience is not just the science of the small, but the science where materials with small dimensions demonstrate new physical phenomena, collectively described as quantum effects. Quantum effects are size-dependent and significantly differ from the properties of macroscaled or bulk materials. The changed properties may involve, though not limited to, color, solubility, strength, electronic and thermal conductivities, magnetic behavior, mobility, chemical and biological activities, etc.<\/p>\r\n \r\n\r\n\"\"\r\n\r\n \r\n

Figure 3 Three and a half gold atoms (each with the covalent radius of 0.144 nm) positioned adjacently in a row equal 1 nm.<\/strong><\/p>\r\n\r\n<\/div>\r\n

\r\n\r\n\u00a0 \u00a0 1.2<\/strong>\u00a0\u00a0 Nanomaterials<\/strong>\r\n\r\n \r\n

The objects with at least one dimension in nanometer range (i.e., ~1-100 nm) are termed as nanomaterials.<\/p>\r\nDimension dependent classification of nanomaterials is enumerated in Table 1<\/strong>:\r\n\r\n \r\n\r\n\"\"\u00a0 \u00a0Broadly, nanomaterials are classified into two types:\r\n