carbonnanotubes.pptVIP

Carbon nanotubes John, Sarah, Doug Carbon nanotubes Main interest: Prototypes for a one-dimensional quantum wire. Strength Who found first nanotube? Graphite Graphite Graphite What is tube rolled out of ? How to roll the nanotube ? Different types of nanotubes What are the main properties? Interesting thought from paper. Interesting thought from paper. Dispersion relation in nanotubes Some thoughts: How to make nanotubes? Look like ? * 1970: Morinobu Endo-- First carbon filaments of nanometer dimensions, as part of his PhD studies at the University of Orleans in France. He grew carbon fibers about 7 nm in diameter using a vapor-growth technique. Filaments were not recognized as nanotubes and were not studied. 1991:Sumio Iijima-- NEC Laboratory in Tsukuba-- used high-resolution transmission electron microscopy to observe carbon nanotubes. Hexagonal graphite: Graphite has a structure containing layers of atoms arranged at the corners of contiguous hexagons. (not to be confused with hexagonal close packed). The ease with which layers slide against each other is consistent with the much larger distance between carbon atoms in different layers (335?pm) than between carbon atoms in the same layer (142?pm). The lattice constant a = 246.6 pm C=669 pm An ideal nanotube can be thought of as a hexagonal network of carbon atoms that has been rolled up to make a cylinder. width: nanometer: capped with half of a fullerene molecule. length: microns A carbon nanotube is based on a two-dimensional graphene sheet. The chiral vector is defined on the hexagonal lattice as Ch = na1 + ma2, Chiral angle Role/cap off (n, 0) or (0, m) and have a chiral angle of 0°, armchair nanotubes have (n, n) and a chiral angle of 30°, while chiral nanotubes have general (n, m) values and a chiral angle of between 0° and 30°. Diameter of nanotube Chiral angle Both depend on n and m. Diameter=length of chiral vector divided by 4 (has to do with the capping) Quote: “Since