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Kolokviji na IJS

Topology, structure and defects in carbon nanosystems

author: Chris P. Ewels, Institute of Materials (IMN)

Description

In this talk we will explore how in the last twenty years carbon science has made the fundamental step from the flat world of graphite into the three dimensional world of fullerenes and nanotubes, the building blocks of the carbon nanotechnology revolution. We will look at the history of the discovery of buckminsterfullerene and carbon nanotubes, and explore analogies in diverse fields of biology, architecture and sport.

The understanding of defects in nanocarbons is essential in order to control their diverse properties. For example irradiating bundles of carbon nanotubes produces defects which increase their bending strength by a factor of 16. At the same time such defects can store energy and were the cause of the UK “Windscale” nuclear fire in the 1950s. Recent advances in computational modelling and electron microscopy mean that we now have a much better understanding of the structure, formation and evolution of intrinsic defects, opening up the intriguing possibility of selective spatial creation of defects – atomic level defect engineering.

Categories

Top: Chemistry

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Slides
0:00 Topology, structure and defects in carbon nanosystems
1:53 Institute of Materials Nantes, France
2:16 slide3
2:29 In English often called a “lead pencil” Not correct! It´s actually GRAPHITE One of the pure forms of carbon
2:46 Carbon
3:07 slide6
3:36 slide7
3:55 3 equivalent bonds leads to formation of hexagons
3:56 slide9
4:14 Graphite sheets are flat
4:23 slide11
5:05 slide12
5:46 Graphite Electrodes
6:02 Vacuum
6:07 Generate a large electric spark between two graphite electrodes, and study the soot that comes off…
6:20 Exxon Data Cox et al JACS 110 1588 (1988)
7:17 slide17
7:31 slide18
7:50 C60 Buckminsterfullerene “Buckyball”
8:03 Generate a large electric spark between two graphite electrodes, and study the soot that comes off…
8:16 How do we make a pentagon from graphite?
8:22 How do we make a pentagon from graphite?01
8:28 How do we make a pentagon from graphite?02
8:32 How do we make a pentagon from graphite?03
8:56 Pentagon
8:59 12 pentagons and any number of hexagons will form a closed object
9:16 slide27
9:27 Zoran Pavlovic
9:32 Jonathan Hare Creative Science Centre
9:59 H. Kroto
10:10 H. Kroto01
10:17 H. Kroto02
10:22 H. Kroto03
10:23 H. Kroto04
10:39 slide35
10:44 Ernst Haeckel The Art of Nature 1900
11:04 Ernst Haeckel The Art of Nature 1900 01
11:08 Ernst Haeckel The Art of Nature 1900 02
11:23 slide39
11:33 slide40
11:35 From patent application of R. Buckminster Fuller for “geodesic dome”.
11:52 From patent application of R. Buckminster Fuller for “geodesic dome”.
12:12 slide43
12:15 EPCOT Centre, Florida, USA
12:20 Buckminster Fuller On the cover of Time Magazine
12:24 Buckminster Fuller On the cover of Time Magazine
12:26 Buckminster Fuller On the cover of Time Magazine
12:30 How else can we go from flat to curved?
12:49 Nanotube
12:59 slide50
13:28 slide51
13:48 Typical Nanotube Properties
13:59 Typical Nanotube Properties01
14:25 Harry Kroto
14:38 Harry Kroto01
14:45 Nanotube flexing
15:11 Arc-electric process makes nanotubes too (as for C60)
15:19 © Calvin (2006)
15:27 slide59
15:32 slide60
15:52 M. Endo (Shinshu University)
16:10 slide62
16:24 Also Multi-walled Carbon Nanotubes (tubes within tubes)
16:37 64
16:52 Single walled nanotubes containing Li metal produced by electrolysis
17:05 1nm
17:08 Electronic Properties?
17:13 Electronic properties depend on how the tubes are rolled, and what diameter they have.
17:45 Cees Dekker, Delft Institute of Technology, the Netherlands
17:53 A nanotube transistor using conventional silicon as the “gate” (switch)
18:00 The “kink” separates metallic and semi-conducting regions
18:13 Current-voltage characteristics across the kink at 100 K.
18:20 Nanotubes for field-emission
18:36 Spinning fibres with a composite of carbon nanotubes and a polymer matrix
19:39 Damaging Nanotubes
19:49 Damaging Nanotubes 01
20:48 Defects improving mechanical properties
21:53 Defects improving mechanical properties01
23:06 Defects reducing mechanical properties
24:00 Defects reducing mechanical properties01
24:30 Defects reducing mechanical properties 02
25:30 “Active Sites” also good for…
27:20 How to induce ‘active sites’?
27:39 Convergence
28:08 Electron microscopy of ‘pea-pod’ defects
28:45 Electron microscopy of ‘pea-pod’ defects 01
29:27 Electron microscopy of ‘pea-pod’ defects 02
30:25 What happens when we shine an electron beam on a carbon nanotube?
30:57 What happens when we shine an electron beam on a carbon nanotube? 01
31:15 Molecular dynamics simulations of emission process
32:13 Calculation of the ejection energy threshold through DFT methods
32:29 Emission energy threshold anisothropy
32:50 Below the irradiation energy threshold
33:26 Below the irradiation energy threshold 01
34:27 Below the irradiation energy threshold 02
34:40 Just above the irradiation energy threshold
35:39 slide97
36:03 slide98
36:11 Thanks to…

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