Dr.G.V.S Jayapale Rao
Sr. Lecturer in Physics
Maharajah’s College, Vizianagaram
Andhra predesh. India
Email: [email protected]
Whatsup Number: 9492020115
Research Advances for physics scholars in Nanotechnology: Dr.G.V.S.jayapala Rao
Abstract: Nanotechnology (the technologies which deals with the objects, systems whose measured size is less than 100 nm in at least one dimension with quantum confinement) consists of Nanoscale materials, structures, devices and sensors etc.,.At nanoscale, quantum effects dominate the behaviour of matter affecting the physical, chemical and biological behavior of materials. For example: copper can become transparent platinum which is inert material can become catalyst, aluminum can turn as combustible, solids can turn into liquids like gold and insulators can became conductors like silicon. In the case of bad conductors changes in physical properties can be observed when the particle size is the range 50-100nm whereas in metallic systems, appreciable changes can be observed only when the particle size is much below of 5nm. Therefore, intensified and adequate research methodologies are required (need to be developed if necessary) to describe the behaviour of the nanoscale materials and systems with regard to venues of their applications.
Key words : Nanotechnology, Nanoscale, Quantum effects, XRD, TEM
Introduction: Nanotechnology is the science of management and manipulation of atoms and molecules to design an object, system or device at nanoscale (size <100 n min at least one dimension). Nanotechnology is the supramolecular technology which means it is the engineering of functional systems at the molecular or supramolecular scale. Materials can exhibit different properties based on its size and shape at nanoscale compared to their bulk counter parts.(Macnaghten 2010; Pidgon at 2011). National Nano technology initiative (NNI), established in the year 2000 in the united states (US), declared that nanotechnology is helping to considerably improve, even revolutionize, many technologies and Industry sectors including Information technology, energy, environmental science, medicine, homeland security, food safety and transportation, among many others (NNI 2018 a). The responsible development of Nano technology that addresses the ethical, legal and societal issues (ELSI) of Nano technology is one of the NNI’s four objectives, understood to advance the other i.e. research, commercialization, worker education and public engagement.
History and development of nanotechnology:-
At the beginning of the 20th century, when scientists felt that atoms were abstract entities used for the purpose of calculations, it was Albert Einstein also explained the “jittery dance of microscopic particles – brownie motion. Almost 50 years after Einstein’s prediction about the existence of atom, in 1959, Richard P. Feynman suggested that it should be possible to build machines small enough to manufacture objects with atomic precision. Feynman said, “ What I want to talk about is the problem of manipulating and controlling things on a small scale. The term “Nano technology” rapidly became popular. The Government of India, in may 2007 launched a mission on Nano science and Nano technology called as Nano mission. A basic knowledge of physics of law – dimensional systems helps a great deal in understanding the nuances of Nano science. It is difficult to describe the history of Nano technology which, according to R.D. Booker is due to two Principal reasons 1) Ambiguity of the term Nano technology and 2) Uncertainty of the time span corresponding to the early stages of NT development. The term Nano technology is explained by a wide spectrum of various technologies that Nano technology covers, which are based on various types of physical, chemical and biological process, realized at Nano level.
Synthesis Techniques for the preparation of Nanoscale particles:-
For synthesis of nanomaterials there are seven methods widely known as high energy ball milling, laser ablation, plasma synthesis, inert gas condensation, electro depositions, sol-gel synthesis and biosynthesis. After the completion of synthesis process of the nanomaterial, we will go through some of the important characterization techniques such as UV-Vis spectroscopy to record the characteristic absorbance, Dynamic light scattering (DLS) for the measurement of hydrodynamic diameter (HDD), X-ray diffraction (XRD) for the structural determination, Fourier Transform Infra-red spectrometry (FT-IR) for the identification of the functional groups in the hydrosoland Transmission electron microscopy (TEM), Scanning tunneling electron microscopy (STEM) for the surface morphological studies’ In a broader sense, two approached are to be followed for the synthesis of nanoscale materials.
- Top-down approach
- Bottom – up approach.
Top -down approach
High energy ball milling: – One of the top – down routes is the mechanosynthesis or mechanical method that is capable of producing Nano scale particles by mechanical attrition. A schematic of the ball milling unit can be used for downsizing micrometer – sized powders to Nano scale. The kinetic energy of the grinding medium is transferred to coarse grained metals, alloys, ceramics etc., to achieve the desired size of the nanoparticles.
Laser Avaporation: Laser ablation or photo ablation is the process of removing material from a solid or (Occasionally liquid) surface by irradiating it with or laser beam. At low laser flux, the material is heated by the absorbed laser energy and evaporates or sublimates. At high laser flux, the material is typically converted into a plasma.
Plasma synthesis: Plasma synthesis of Nano particulate powders covers all processes where changed particles are observed. It was covered ranges from high temperature processes and micro laser processes to the laser and flame synthesis of Nano powders. Plasma processes may be well suited to the production of larger quantities of good quality.
Inert gas condensation: Inert gas condensation is an easiest method for the preparation of the metallic Nano particles and Nano compositions. Evaporate the metal or inorganic substances followed by the condensation, which is rapid and controlled to prepare the Nano particles of the desired size. The vaporization of the material can be carried out by any sort of the source as spluttering plasma heating, laser vaporization, electric is discharging or thermal vaporization. The required spontaneous condensation is carried out by the collection of the vaporized Nano particles on surface with relatively low temperatures.
Electro – depositions: -Metalliccoatings are obtained in a conducting substrate by electro – deposition. The process involves basically the reduction of metalons to produce metal atoms which are deposited on the cathode. Pure metals, such as copper, nickel, cobalt, gold, silver, etc. can be deposited from their salts by the reduction process.
Sol – Gel process: Sol– gel is one of the method to the preparation of new materials. This acts as a better control of the alone reactions involved during the synthesis of solids. Homogenous multi – component systems can be easily obtained, particularly homogenous mixed solids can be prepared by mixing the molecular precursors solutions. The purpose of the work is to better understanding the chemistry involved during the preparation of mixed oxides by sol – gel process.
Biosynthesis:- Plant, microbe, biotemplate – mediated biosynthesis of Nano particle is considered a widely acceptable technology for rapid production of metallic Nano particles for successfully meeting the excessive need and current market demand and resulting in a reduction in the employment of hazardous substances to public health. (Nyoman Rupiasih el al .2013). Biological materials provide an environ – friendly green chemistry method to produce invaluable inorganic Nano scale materials as the protocol aliminates using plants and plant materials is effective and simple (Prasad and Elumalai, 2011).
Classification of nanoscale materials:
Nanoparticles can be classified into different types according to the size, morphology physical and chemical properties. Some of them are carbon- based nanoparticles (carbonaceous), ceramic nanoparticles, metallic nanoparticles, semiconductor nanoparticles, polymeric nanoparticles and lipid- based nanoparticles.
Of all, herein, we would like to discuss about semi-conductor Nano particles. Semiconductor nanoparticles have properties like those of metals and nonmetals.; They are found in the periodic table in groups II-VI, III-V or IV-VI, those particles have wide bandgaps, which as tunings shows different properties they are used in photocatalysis, electronic devices photo-optics and water splitting applications some examples of semiconductor nanoparticles are GaN, GaP InP, In As from group III-V, ZnO, ZSs, CdSeCdTe are II-VI semiconductors are silicon and germanium are from group IV. The important components in nanoworld is the energy consideration of small clusters of particles with the help of scanning tunneling microscope (STM). The density of states (DOS) formulation describes the number of electronic states that are available in a system.
The search for new magneticmaterials brought with it the development of metallic based materials, such as iron, combined with unique nanocrystalline structures and properties that were never seen or had not yet been obtained. This fact is reflected in research is this area, whose focus as changed from the micro crystalline to the Nano crystalline size. Thus, its application in the fields of biomedicine, molecular biology, biochemistry, diagnosis, catalysis and various other industrial applications are increasingly being measured, these materials can be used both as magnetic particles and as magnetic fluids.
Nano technology laboratory research and analysis:
Expertise in synthesis and application of Nano scale materials and nanoscale devices and systems is now emerging. Intertek analytical Nano technology laboratories measure Nano – particle size, morphology, dispersion, uniformly, optical and physical properties and chemical composition. Nano technology research seeks to design and manufacture small particles, then incorporate these particles into liquid or solid carrier materials, Nano scale materials research and development.
Analysis of Nanoscale particles:
There are a number of techniques and devices being employed for the chemical analysis and characterization of the nanoscale particles to identify their chemical, structural and morphological details.
- Analysis of particles size and morphology using electron microscopy.
- Application of image analysis to generate quantitative information on size and shape distributions.
- Carbon Nano tubes analysis using Raman spectroscopy to monitor tube diameter and sample purity and thermogravimetric analysis (TGA) as well as elemental analysis to provide information on sample purity or catalyst residue content.
- Coating analysis using spectroscopic techniques or by surface analysis.
- Scratch testing
Nano dispersion analysis:
- Optimum properties are dependent on achieve uniform dispersion and sometimes on the control of orientation.
- Use of techniques such as electron microscopy, x- ray diffraction and spectroscopic methods to characterize the composite morphology and quantity aspects of homogeneity or orientation.
- Development of on – live measurements, as part of a manufacturing process.
- Processing of Nano materials:
- Polymer matrix, filler content, physical properties and processing conditions investigations.
- Mechanical properties (eg: toughness, scratch resistance or impact strength)
- Optical performance (eg. Clarity, reflectance, refractive index)
- Data collection:-
- Primary data: The primary data is collected by in the form of communication and observations.
- Secondary data: This is collected both internally and externally from the previous records and research papers. This includes publications and internet.
This paper intends to give an over view of the nanoscale materials, their synthesis and characterization techniques. However, in depth study of available literature and acquired practical skills are the essentials for anybody who is interested to work in nanotechnologies for their applications in an array of avenues including agriculture and medicine.
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- Asa Boholm, Simon Larsson< A literature review as challenges facing the communication of NI to the public. Springer.
- S. Rmachanadra Rao, Shubra Singh (2013); NS, NT Fundamentals to Frontiers; Wiley India pvt.ltd.
- Prasad, TNVKV and Elumalai, EK (2011); Bio fabrication of Ag Nano particles using moringa Oleifere leaf extract and their antimicrobial activity; Asian Pac. J. Prof. Biomed; 439 – 442.