Talk:Allotropes of carbon
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Carbines or something like that
There are a lot of information in foreign languages that there are ...=C=C=C=C=...and ...—C≡C—C≡C—... fibers. How are they called? —The preceding unsigned comment was added by 188.8.131.52 (talk • contribs) .
In an effort to de-stub the article, I've pretty much made it a list of carbon allotropes with a few paragraphs ripped from their respective articles, but I've kept the comparisons the original contributor made at the bottom. Feel free to discuss any changes or points of contention with me. Jongpil Yun 22:44, 28 January 2006 (UTC)
Question regarding this line (under Diamond): "Each carbon atom in diamond is covalently bonded to four other carbons in a tetrahedron." Even after looking up tetrahedron, I still couldn't tell if this is right. If each carbon atom is bonded to 4 others, aren't there then 5 atoms total? Is that still a tetrahedron? Or are there 4 carbons on each corner and one on the inside like methane? Gaviidae 16:18, 29 October 2006 (UTC)
- Yes, just like methane, only instead of each hydrogen there's another carbon. —Ilmari Karonen (talk) 19:27, 29 October 2006 (UTC)
Graphene seems to be a newly discovered form of carbon. The article on "Graphene" says this form of carbon is not an allotrope because the sheets are of "finite" thickness. Like they could be anything else. Surely graphene is an allotrope and should be here or at least have an explanation of why it isn't
I've linked this article here. Perhaps someone would like to start a section on this. --Rifleman 82 09:41, 29 October 2007 (UTC)
Not Clear What an Allotrope and What a Variant
Currently it's not clear what of the materials discussed is a basic allotrope and what a variant, and how many basic allotropes there are.
Some specific issues --
- Why do different shapes of fullerenes not qualify are distinct allotropes?
- Buckminsterfullerene is commonly described as the third allotrope of carbon discovered:
"For their discovery of the buckyball — the third form of pure carbon to be discovered after graphite and diamonds — Kroto and his Rice colleagues, Robert Curl Jr. and Richard E. Smalley, were awarded the Nobel Prize for chemistry in 1996."
-- and yet Lonsdaleite and Linear Acetylenic Carbon (and maybe others as I haven't read through carefully) seem to predate it here.
- The article states "Carbon nanofoam is the fifth known allotrope of carbon discovered in 1997" -- same issues with precedence.
Etc. The article should be organized to list the allotropes in order of discovery, with a statement giving the date and order -- "X was the third allotrope of carbon discovered, in DATE..."
BTW are newly synthesized forms (which have not been found to exist in nature) "discovered" or "invented" -- and can they be patented?
Carbyne Is Most Stable
The most stable allotrope of carbon is NOT graphite. It is carbyne; it has smallest heat of combustion (lower than even that of graphite). I'll look up in tables. However graphite and diamond may transform into each other, carbyne doesn't participate (i.e. reactions are extremely slow). 184.108.40.206 (talk) 03:52, 5 June 2012 (UTC)
Does graphite naturally transform to carbyne? Carbyne is less metallic than graphite. Interestingly, black P and grey Se are more "metalloids" metallic than carbyne, which is probably only an intermediate between metalloids and nonmetals (very strong and probably with high melting point, but insulating). Does carbyne spontaneously transform to graphite and is in fact unstable, far much less stable than graphite, diamonds or fullerenes?
Fullerenes have a distinct property - unlike diamond and graphite, which are exceprtionally nonvolatile (especially for a such nonmetallic element), they are extremely volatile when we compare their molar mass or number of protons in the molecule to their sublimation points. They have narrower band gaps (less than 2 eV) than some allotropes of boron and have similar electrical conductivity at normal temperature. Boron is an intermediate between metals and nonmetals, fullerenes are intermediates between metalloids and good nonmetals (such as diamond, which is also an intermediate, which has many metalloidal properties: extremely high melting point, hardness, density, thermal conductivity).
Any information on a form called M-Carbon? If the article at http://news.yale.edu/2012/07/19/diamond-rough-half-century-puzzle-solved is correct, some of the comments on diamond are now incorrect (apparently the new form can damage diamond).
Link to better article: http://www.nature.com/srep/2012/120719/srep00520/full/srep00520.html — Preceding unsigned comment added by 220.127.116.11 (talk) 00:10, 23 July 2012 (UTC)
Some of the more metallic allotropes are: metallic nanotubes, graphene, graphite, glassy carbon, less metallic - diamond, carbyne, fullerenes.
Text about predicted "metallic carbon crystal" at STP (what should be its band structure)?
About other "metallic carbon":
Metallic Carbon Materials
Alex Zettl, Vincent Crespi, Marvin Cohen and Steven Louie from Berkeley Lab have introduced heptagons and pentagons into a hexagonal, semimetallic, graphite network, and obtained metallic, strong, covalently-bonded materials of pure carbon. This new invention allows the formation of metallic, pure carbon films and bulk materials, some of which are predicted to be superconductors.
The new metallic carbon materials have improved metallic properties that will work well in any application that presently uses graphite. In addition, these light-weight, metallic materials are extremely strong in the planar directions. They can be used when a mechanically strong and/or metallic film is required. They can be used in field emitters and electromagnetic shielding; in thin film resistors, heaters, radiation detectors and interconnects in devices; high strength conductive fibers; high temperature electrical components; battery electrodes and lubricants.
Is any form of pure carbon superconductor at ambient pressure?
And carbon looks generally more metallic than popurarily classified as a metalloid selenium. Very high sublimation, boiling and melting point of many forms of carbon (which is inadequate to nonmetls, but adequate to metalloids) is one of the arguments. Even "nonmetallic" diamond is better of all metals in some clssifications popurarily associated with metals. But these two elements are in fact very similar in the general metallic character and have to be classified in the same metallicity class.