Introduction to nano materials for Engineering students

Introduction to nanomaterials

1. Introduction to Nanomaterials (CHEG8245) AASTU Department of Chemical Engineering 2023

2. Definitions The prefix “ Nano” is derived from the Greek word which means “Dwarf ”. Nanomaterials : Materials that have at least one dimension in nanometric scales with a size range of 1 to 100 nm Materials that exhibit fundamentally different characteristics from those of their bulk counterparts

3. Nanotechnology is a branch of science and engineering which deals with creation of materials, devices and systems through the manipulation of individual atoms and molecules. is the understanding and control of matter at dimensions of roughly 1to100 nanometers, where unique phenomena enable novel applications It is a multidisciplinary field where chemists, physicists, medical doctors, engineers, biologists and computer scientists are working and collaborating for its development.

4. Historical back ground The idea of molecular manufacturing was first conceived in 1959 by the famous professor of physics Dr. Richard P. Feynman at the presentation on the American Physical Society meeting in his famous speech “There’s Plenty of Room at the Bottom” Gordon E. Moore (1965), the co-founder of Intel Corporation, made an amazing forecast: the number of transistors on a chip of given area would double in every 1.5 yrs. His prediction indicated that today’s transistors would lie in the nanoregime .

5. The term “ Nano technology ” had been coined by Norio Taniguchi in 1974 Gerd Binnig and Heinrich Rohrer of IBM, Zurich Research Laboratory invented the Scanning Tunneling Microscope (STM) in 1981 (they were awarded Noble Prize in 1986 for the STM invention) Atomic Force Microscope Microscope ( AFM), which did not require the specimen to be conducting, is invented in 1985 by Binnig along with Gerber and Quate Heinrich Rohrer Gerd Binnig

6. In 1991, carbon nanotubes were discovered by another Japanese scientist, Sumio Iijima In 2016 , Nobel Prize in Chemistry : Jean-Pierre Sauvage , Sir J. Fraser Stoddart , and Bernard Feringa , for the novel idea of turning molecules into machines

7. Why nano technology? High surface area to volume ratio As objects get smaller they have a much greater surface area to volume ratio As objects get smaller they have a much greater surface area to volume ratio 2 cm cube has a surface area of 24 cm 2 and a volume of 8 cm 3 (ratio=3:1) 10cm cube has a surface area of 10 cm cube has a surface area of 600 cm 2 and a volume of 1000 cm 3 (ratio=0.6:1 )

8. Small size effect (Quantum confinement effect) The particles are so small that electrons are not free to move about as in bulk gold. As the movement is restricted, the particles react differently with light . Electronic states are quite different from bulk. Discrete energy levels; Quantum confinement effect occurs, increases the energy gap between energy levels leading to metal to semiconductor to insulator transition. Gold

9. Decreased imperfections and defects: This more structural perfection in the nanomaterials improves their mechanical properties (increases mechanical strength e.g. hardness, toughness etc .). Other property changes Tunable fluorescent emission Electrical conductivity Magnetic Property changes Biological Property

10. Classification of nano materials Usually classified based on the number of dimensions, which are not confined to the nano scale range (< 100nm) 0D (dimensional) nanomaterials QC occurs in all the three direction e.g . quantum dot – nano particles , nano cubes etc.

11. 1D (dimensional) nanomaterials QC occurs in two direction e.g. nanotubes, nanorods , nanowires, etc. 2D (dimensional) nanomaterials QC occurs in one direction e.g. Ultrathin film, ultrathin layer etc. 3D-bulk system all the three dimensions are in the macroscopic range

12. example Category of nanomaterials nanowires, nanofibres made from a variety of elements other than carbon, nanotubes and, a subset of this group, carbon nanotubes. One-dimensional nanomaterials layers, multi-layers, thin films, platelets and surface coatings. They have been developed and used for decades, particularly in the electronics industry. Two-dimensional nanomaterials are known as nanoparticles and include precipitates, colloids and quantum dots (tiny particles of semiconductor materials), and Nanocrystalline materials Three-dimensional nanomaterials

13. Nano materials synthesis approaches Top-down – Breaking down matter into more basic building blocks. Frequently uses chemical or thermal methods. Bottoms-up – Building complex systems by combining simple atomic-level components.

14. Application of nanomaterials