1. 1 Structure of matter Lec. (7)

2. www.scifun.ed.ac.uk/card/flakes.html Graphite – Van der Waals Bonds 2

3. www.webelements.com Graphite 3

4. Soft and slipperyMany strong covalent bonds holding the structure together but only in 2 dimensions. The layers are free to slide easily over one another. Graphite powder is used as a lubricant. Brittle All of the bonds are directional within a layer and stress across a layer will tend to break them. Graphite rods used for electrolysis easily break when dropped. Electrical conductor Only three of the valence (outer shell) electrons are used in sigma bonding. The other electron is in a 'p' orbital which can overlap laterally with neighbouring 'p' orbitals making giant molecular pi orbitals that extend over the whole of each layer. Electrons are free to move within these delocalised pi orbitals. Insoluble in water. There are only very weak Van der Waal's attractions between the carbon atoms and the water molecules whereas the carbon atoms are bonded very tightly to one another. Very high melting point Many strong covalent bonds holding the layers together - it requires massive amounts of energy to pull it apart Graphite 4

5. www.webelements.com Diamond 5

6. HardMany strong covalent bonds holding the structure together. BrittleAll of the bonds are directional and stress will tend to break the structure (In a malleable substance, such as for example a metal, the bonding is non-directional and can still act if the particles are displaced with respect to one another). InsulatorAll of the valence (outer shell) electrons are used in bonding. The bonds are sigma and the electrons are located between the two carbon nuclei being bonded together. None of the electrons are free to move Insoluble in water.There are only very weak Van der Waal's attractions between the carbon atoms and the water molecules whereas the carbon atoms are bodned very tightly to one another. Very high melting pointMany strong covalent bonds holding the structure together - it requires massive amounts of energy to pull it apart Diamond 6

7. www.webelements.com Diamond 7

8. Properties & Applications Electrical Mechanical Thermal Storage Nanocarbon http://www.youtube.com/watch?v=4yRjYiw_H_s 8

9. Discovered in 1985 Nobel prize Chemistry 1996 Curl, Kroto, and Smalley Fullerenes 9

10. Buckyballs C 60 32 facets (12 pentagons and 20 hexagons) C 70, C 76, and C 84 10

11. Bucky Balls Symmetric shape → lubricant Large surface area → catalyst High temperature (~750 o C) High pressure Hollow → caging particles 11

12. Buckyballs Forms a crystal by weak van der Waals force Superconductivity - K 3 C 60 : 19.2 K - RbCs 2 C 60 : 33 K Kittel, Introduction to Solid State Physics, 7the ed. 1996. 12

13. Buckyballs Forms a crystal by weak van der Waals force Superconductivity - K 3 C 60 : 19.2 K - RbCs 2 C 60 : 33 K http://invsee.asu.edu/nmodules/Carbonmod/crystalline.html 13

14. Soft and slipperyFew covalent bonds holding the molecules together but only weak Vander Waals forces between molecules. BrittleSoft weak crystals typical of covalent substances Electrical InsulatorNo movement of electrons available from one molecule to the next. The exception could be the formation of nano-tubes that are capable of conducting electricity along their length. These are the subject of some experiments in micro electronics Insoluble in water.There are only very weak Van der Waal's attractions between the carbon atoms and the water molecules whereas the carbon atoms are bonded very tightly to one another in the molecules. Low Melting Point SolidsTypical of covalent crystals where only Van der Waal's interactions have to be broken for melting. Buckyballs 14

15. Carbon Nanotubes (CNT) Like graphite but all coiled up Typically 10 Angstroms in diameter Can be electrically conductive or semiconducting SWNT and MWNT –Composites, transistors, hydrogen storage Courtesy of and ©Copyright Professor Charles M. Lieber GroupProfessor Charles M. Lieber Group 15

16. Nanotube 16

17. The "armchair" type has the characteristics of a metal The "zigzag" type has properties that change depending on the tube diameter The "spiral" type has the characteristics of a semiconductor Armchair Zigzag Spiral 17

18. Nanotube Zheng et al. Nature Materials 3 (2004) 673. SWCNT – 1.9 nm Diameter: as low as 1 nm Length: μm to cm High aspect ratio: → quasi 1D solid 18

19. Nanotube Intro Video Earth and sky: Properties of Nanotubes http://www.youtube.com/watch?v=zQAK4xxPGfM&mode=related&search=Nanotube 19

20. Introduction A carbon nanotube (CNT) is a tubular molecule with axial symmetry and diameter in the nanometer range (Muller). It can be considered as a rolled up graphene sheet. However, it possesses many properties that leave no doubt this is not just graphene. http://www.nanotech-now.com/nanotube-buckyball-sites.htm http://www.msm.cam.ac.uk/phasetrans/2005/paper/img19.png

21. Types Single Walled CNT (SWCNT): one-atom-thick CNTs Multi Walled CNT (MWCNT): concentric layers of CNTs http://www-ibmc.u-strasbg.fr/ict/images/SWNT_MWNT.jpg

22. Properties Among some of the properties of the CNTs we can find: Electrical: Both metallic and non- metallic behaviors are observed, while geometry plays a profound part in determining the electronic behavior. (Ebbesen) Elastic: Tensile Young’s module and torsion shear module comparable to that of diamond (Lu). http://www.studentsoftheworld.info/sites/family/img/27335_Electricity.jpg http://www.nanoshel.com/research-center/wp-content/uploads/2009/01/ballistic-impact.jpg

23. Properties Mechanical: Carbon nanotubes have high strength plus extraordinary flexibility and resilience. (Salvetat) Thermal: Thermal expansion of carbon nanotubes will be essentially isotropic that is, uniform in all directions (Ruoff). http://brent.kearneys.ca/wp-content/uploads/2006/05/carbon_nanotube.jpg

24. Nanotube Stats Current capacity Carbon nanotube 1 GAmps / cm 2 Copper wire 1 MAmps / cm 2 Thermal conductivity Comparable to pure diamond (3320 W / m. K) Temperature stability Carbon nanotube 750 o C (in air) Metal wires in microchips 600 – 1000 o C Caging May change electrical properties → can be used as a sensor 24

25. Nanotubes Carbon nanotubes are the strongest known material. Young Modulus (stiffness): Carbon nanotubes 1250 GPa Carbon fibers 425 GPa (max.) High strength steel 200 GPa Tensile strength (breaking strength) Carbon nanotubes 11- 63 GPa Carbon fibers3.5 - 6 GPa High strength steel ~ 2 GPa Elongation to failure : ~ 20-30 % Density: Carbon nanotube (SW) 1.33 – 1.40 gram / cm 3 Aluminium 2.7 gram / cm 3 25

26. Synthesis of Carbon Nanotubes IFW-Dresden Carbon Nanotubes http://www.youtube.com/watch?v=tgToxaOqF10&mode=related&search=Nanotube Synthesis of Carbon nanotube http://www.youtube.com/watch?v=8N79nlhwcgM&mode=related&search=C60%20Ful lerene%20Fullereno%20Buckyballhttp://www.youtube.com/watch?v=8N79nlhwcgM&mode=related&search=C60%20Ful lerene%20Fullereno%20Buckyball Growth of Carbon nanotube http://www.youtube.com/watch?v=1p8vFdCJRZE&NR=1&feature=fvwp 26

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30. http://www.youtube.com/watch?v=HIGMB_R3pgI&feature=related http://www.youtube.com/watch?v=nTbz8w1SB1U&feature=fvw Water Resistant Coatings 30

31. Carbon Fiber A 6 μm diameter carbon filament (running from bottom left to top right) compared to a human hair. 31

32. Sports Equipment CNT Carbon Nanotube Opti-Flex composite handle technology, provids maximum handle flex-three times greater than aluminum 32

33. Carbon Nanotube/Cement Composite Systems In concrete, they increase the tensile strength, and halt crack propagation. 33

34. www.nanooze.org The Space Elevator http://www.youtube.com/watch?v=lVV0S9cNLKI&feature=related 34

35. www.enterprisemission.com 35

36. Space Elevator NOVA space elevator intro http://www.youtube.com/watch?v=pnwZmWoymeI& mode=related&searchhttp://www.youtube.com/watch?v=pnwZmWoymeI& mode=related&search 2 minute space elevator intro http://www.youtube.com/watch?v=F2UZDHHDhog Space Elevator Competition: USST's First Place Climb http://www.youtube.com/watch?v=VkdfuQdoW_Q&mode=related&sear ch=space-elevator%20turbo%20crawlerhttp://www.youtube.com/watch?v=VkdfuQdoW_Q&mode=related&sear ch=space-elevator%20turbo%20crawler 36

37. CNT light bulb filament: alternative to tungsten filaments in incandescent lamps The average efficiency is 40% higher than that of a tungsten filament at the same temperature (1400–2300 K). 37

38. Nano Radio http://nsf.gov/news/news_summ.jsp?cntn_id=110566 38

39. http://nsf.gov/news/news_summ.jsp?cntn_id=110566 When a radio wave of a specific frequency impinges on the nanotube, it begins to vibrate vigorously. An electric field applied to the nanotube forces electrons to be emitted from its tip. This electrical current may be used to detect the mechanical vibrations of the nanotube, and thus listen to the radio waves. 39

40. Nanotube Radio http://www.youtube.com/watch?v=gkQkzvnstkg http://www.youtube.com/watch?v=yQz9C7yE1kc &feature=relatedhttp://www.youtube.com/watch?v=yQz9C7yE1kc &feature=related 40

41. Carbon Nanotube Electronics Carbon nanotube in microchip http://www.youtube.com/watch?v=74YkJYT7Uj4&mod e=related&search=Nanotubehttp://www.youtube.com/watch?v=74YkJYT7Uj4&mod e=related&search=Nanotube Customized Y-Shaped Nanotubes http://www.youtube.com/watch?v=SGWHBQQKmOs Transistors – the active component of virtually all electronic devices, are what we refer to as electronic switching devices. In a transistor, a small electric current can be used to control the on/off of a larger current. 41

42. Semiconducting CNTs have been used to fabricate field effect transistors (CNTFETs). The electron mean free path in SWCNTs can exceed 1 micron (this is very large) therefore it is projected that CNT devices will operate in the frequency range of hundreds of GHz. 42

43. Kavli Institute Delft SEM image of superconducting transistors 43

44. CNT-FED Professor George Lisensky http://mrsec.wisc.edu/Edetc/cineplex/nanoquest/applications.html http://mrsec.wisc.edu/Edetc/cineplex/nanoquest/applications.html 44

45. CNT-FED Carbon nanotubes can be electrically conductive and due to their small diameter of several nanometers, they can be used as field emitters with extremely high efficiency for field emission displays (FED). The principle of operation resembles that of the cathode ray tube, but on a much smaller length scale. 45

46. Bucky Paper A thin sheet made from nanotubes that are 250 times stronger than steel and 10 times lighter that could be used as a heat sink for chipboards, a backlight for LCD screens or as a faraday cage to protect electrical devices 46

47. Warwick ICAST http://www.youtube.com/watch?v=i4Ax8sY2U4A&mode=related&search=Nanotube 47

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49. Hydrogen Storage Carbon nanotubes covered in titanium atoms provide a very efficient method for storing hydrogen. 49

50. 'Artificial muscles' made from nanotubes "Artificial muscles" have been made from millions of carbon nanotubes. Like natural muscles, providing an electrical charge causes the individual fibers to expand and the whole structure to move. 50

51. Bone cells grown on carbon nanotubes Researchers at the University of California, Riverside have published findings that show, for the first time, that bone cells can grow and proliferate on a scaffold of carbon nanotubes. Scientists found that the nanotubes, 100,000 times finer than a human hair, are an excellent scaffold for bone cells to grow on. http://biosingularity.wordpress.com/2006/03/21/researchers-grow-bone-cells-on- carbon-nanotubes/ http://neurophilosophy.wordpress.com/2006/03/17/123/ 51

52. Nano SQUID A SQUID is a superconducting interferometer device. SQUID devices can be used to monitor infinitesimally small magnetic fields or currents. The originality of this work, is to use gate-tunable carbon-nanotubes (CNT) for the Josephson junctions. The device combines features of single electron transistors with typical properties of a SQUID interferometer. The gate tunability of the CNT junctions enhance the sensitivity of the device which can in principle detect the spin of a single molecule. 52