Scientists see formation of carbon linked nanostructures

November 26th, 2007 - 12:37 pm ICT by admin  

Washington, Nov 26 (ANI): Scientists have observed the actual formation of buckyballs, a family of carbon linked nanostructures, for the first time ever.
Buckyballs, more formally known as buckminsterfullerene C-60, are carbon-linked nanostructures named for their resemblance to the geodesic dome macrostructures, which were favored for their strength by environmentalist Buckminster Fuller .
They are formed by hexagonal and pentagonal arrangements of carbon atoms that seem stitched or welded together, in appearance much like a soccer ball.
Though they have been in theory and widely imaged till now, no one has seen how buckyballs are formed in actuality.
Now, Jianyu Huang, a nanotech researcher in Sandia National Laboratories, US, has seen buckyballs being born through a combination TEM ( transmission electron microscope) and STM (Scanning tunneling microscope).
Huang’s discovery happened unexpectedly.
The researcher was in fact looking for flaws in nanotube durability. Transmitting electric current through the atom-sized tip of a STM, itself inside a transmission electron microscope TEM, he had heated a 10-nanometer-diameter multiwalled carbon nanotube to approximately 2,000 degrees Celsius. After some time, he saw the exterior shells of giant fullerenes form from peelings within the nanotube.
High-resolution 2-D images of the process taken by a CCD camera attached to the microscope showed the fullerenes reducing in diameter, linearly with time, until the structures became the size of C-60, the smallest arrangement of carbon atoms that form the soccerball shape.
“We have now the first direct, in situ, experimental proof of the hypothesis - very significant to the scientific community - that these structures are formed by the heated ’shrink-wrapping’ of carbon sheets,” said Huang.
The heating bends single-atomic-layer carbon sheets into nano bowls, and then adds more carbon atoms to the edge of the bowls until the formation of giant fullerenes - larger, less stable versions of the C-60 molecule.
Continued application of heat reduces these fullerenes, and they ’shrink-wrapped’ to the size of stable C-60 molecules, the buckyball being the smallest stable arrangement of carbon atoms in that shape.
According to Huang, buckyballs have properties which could be useful in the medical field.
“In addition to the strength generated by their carbon-carbon bonds, the structure forms a relatively impermeable cage that conceivably could safely transport molecules of hydrogen for fuel, or tiny doses of medicine to targeted sites within the human body,” said Huang.
But before their widespread use is possible, buckyballs have to be available in large numbers. To achieve that, better understanding of how they form is crucial. (ANI)

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