Talk:Carbon nanotube

From Wikipedia, the free encyclopedia

	Chemistry Portal Carbon nanotube is within the scope of WikiProject Chemicals, a daughter project of WikiProject Chemistry, which aims to improve Wikipedia's coverage of chemicals. To participate, help improve this article or visit the project page for details on the project.
B	This article has been rated as B-Class on the quality scale.
Article Grading: The following comments were left by the quality and importance raters: (edit · refresh) I guess it is a good article, so I've nominated it but until we decide what to do about it it remains a B-article. I rated it High on the importance scale because they could potentially become VERY important in many diffrent branches of the industry... Snailwalker | talk 01:01, 15 October 2006 (UTC)

	Physics Portal This article is within the scope of WikiProject Physics, which collaborates on articles related to physics.
B	This article has been rated as B-Class on the assessment scale.
High	This article is on a subject of High importance within physics.
Help with this template Comments: edit – history – watch – refresh I guess it is a good article, so I've nominated it but until we decide what to do about it it remains a B-article. I rated it High on the importance scale because they could potentially become VERY important in many diffrent branches of the industry... Snailwalker | talk 01:01, 15 October 2006 (UTC)

Carbon nanotube was a good article candidate, but did not meet the good article criteria at the time. Once the objections listed below are addressed, the article can be renominated. You may also seek a review of the decision if you feel there was a mistake. Date of review: 2007-02-08

Carbon nanotube was a good article candidate, but did not meet the good article criteria at the time. Once the objections listed below are addressed, the article can be renominated. You may also seek a review of the decision if you feel there was a mistake. Date of review: 16 October 2006

Carbon nanotube has had a peer review by Wikipedia editors which is now archived. It may contain ideas you can use to improve this article.

This page has been cited as a source by a media organization. See the 2004 press source article for details. The citation is in: "Japanese freeze ice at room temperature", Middle East North Africa, Financial Network, No date..

WikiProject Echo has identified Carbon nanotube as a foreign language featured article. You may be able to improve this article with information from the French language Wikipedia.

Archives Archive 1

Contents 1 Added to defects 2 Data on cost and length? 3 Nanotubes vs. fullerenes 4 Smallest Carbon Fullerene? 5 Bond strength 6 External links and sources 7 nanotubes in mp3 players 8 Question on nanotube diameter 9 adhesion of CNT 10 graphitic wings 11 Health risks and toxicity 12 Progress cleanup 13 63 GPa tensile strength 14 Carbon nanotube tori 15 Additional info on MWNTs? 16 Applications 17 1993 Discovery of single-wall carbon nanotubes 18 Synthesis 19 Ballistic conduction 20 Nanotubes in flames? 21 superconducting nanotubes 22 GA Review 23 Synthesis 24 Mislabelled, misplaced Illustration? 25 "In electric circuits" - completely outdated 26 GA Review 2 26.1 GA failed 27 Thermal 28 The "one-dimensional" nonsense is back

[edit] Added to defects

I have added a few lines discussing in brief the effects of defects on the phonon mean free path in carbon nanotubes and the consequences it has for thermal conductivity. Shepplestone 18.45, 30 April 2006 (GMT)

[edit] Data on cost and length?

I think it'd be quite nice to have a table or plot showing the record for nanotube length each year, and the cost per kg each year. Something like that would be good for getting a handle on length and cost trends over time. I'm not sure where to find such data, though. --131.215.134.7 09:45, 1 May 2005 (UTC)

There are places that sell Carbon Nanotubes: http://www.cnanotech.com/ and http://carbolex.com/

(also see http://home.flash.net/~buckyusa/page16.html)

So it should be possible to at least get a good rating on current pricing. This can use this in combination with mentioned prices at certain dates. --65.66.155.44 23:33, 2 October 2005 (UTC)

Cost varies an incredible amount depending on the makeup up the sample. The variable aspects can include the amount of amorphous carbon, graphite, SWNT/DWNT/MWNT, the density, etc.. The list goes on. I have seen nanotubes sold for 1$/g and 1000$/g. It really just depends. Hellkyte 11:05, 15 June 2006

[edit] Nanotubes vs. fullerenes

The fullerene article says, "They are molecules composed entirely of carbon, taking the form of a hollow sphere, ellipsoid, or tube. Spherical fullerenes are sometimes called buckyballs, while cylindrical fullerenes are called buckytubes or nanotubes."

This article says, "A simple nanotube has a structure similar to a fullerene, but where a fullerene molecule's symmetry is spherical, a nanotube's is cylindrical, with one end typically being capped with half a fullerene molecule."

Which is correct? Are nanotubes fullerenes (and therefore this article needs to be edited), or are nanotubes fullerene-like (in which case the fullerenes article needs to be edited)? I'll see what I can find to back up one version vs. the other. Jon the Geek 15:19, May 3, 2005 (UTC)

The problem with a clear definition in this case is that there is a continuous spectrum of theoretically possible "hollow and cage-like" species in between classical spherical fullerenes and nanotubes. You can have progressively more and more elipsoidal structures that eventually are simply capped nanotubes. Where to draw a line differentiating? I believe "fullerene" refers specifically to the spherical, cage-forms. My evidence is:

1. The Oxford English Dictionary defines fullerene as "Any of several forms of carbon consisting of atoms joined together as a hollow structure, as in buckminsterfullerene." (Where buckminsterfullerene refers specifically to the 60-carbon cage molecule.)

2. According to one textbook I have, there are only five experimentally isolated fullerenes: C₆₀ C₇₀ C₇₆ C₇₈ C₈₄ and that all fullerenes have the composition C_20+2m (exactly 12 pentagons, but m hexagons). This would suggest that nanotubes are not fullerenes.

3. A review on fullerene aromaticity (Buhl, M.; Hirsch, A.; "Spherical Aromaticity of Fullerenes" Chem. Rev.; (Review); 2001; 101(5); 1153-1184. DOI: 10.1021/cr990332q) states "The fullerenes form a unique class of spherical molecules containing a conjugated pi system. Each fullerene represents a closed network of fused hexagons and pentagons. This building principle is a consequence of the Euler theorem which states that for the closure of each spherical network of n hexagons, 12 pentagons are required, with the exception of n = 1." This strongly indicates that "fullerene" refers only to the spherical objects.

4. The IUPAC is the authority on chemistry nomenclature. They state (refer to this PDF):

fullerene

"Compounds composed solely of an even number of carbon atoms, which form a cage-like fused-ring polycyclic system with twelve five-membered rings and the rest six-membered rings. The archetypal example is [60]fullerene, where the atoms and bonds delineate a truncated icosahe-dron. The term has been broadened to include any closed cage structure consisting entirely of three-coordinate carbon atoms."

Certainly the stricter definition seems to refer only to spherical molecules with an even number of carbon atoms (nanotubes do not fit this strict definition).

5. I'm a chemist, and most of the chemists I know use "fullerene" to mean the small, spherical molecules. When they mean "nanotube" they say "nanotube." When they mean "all those new non-graphite and non-diamond carbon structures" they say "fullerenes and nanotubes" or "carbon nanostructures."

There is some ambiguity in that capped nanotubes may end up having the required 12 pentagons on their ends. However, nanotubes typically have aspect ratios that deviate strongly from 1, so I think it is fairly easy to maintain a clear division between nanotubes and fullerenes. Given all this, I believe the concesus in chemistry nomenclature is for fullerenes to refer to spherical cage-like molecules, and nanotubes are thus a distinct allotrope of carbon. I say we update the fullerene artice to reflect this convention. Kebes 22:02, 10 May 2005 (UTC)

Sounds good to me. To throw another wrench into the works... carbon nanowires (or maybe just carbon chains; I can't remember what the C=-C=-C=-C (with =- meant to represent a triple bond) chains are called by the guy at the University of Texas who works with them) should probably also be added to references of the allotropes of carbon, and to the nanowire article.

Should we add organizations doing nanotube research to the article? Such as Postdoctoral Positions in Carbon Nanotube Synthesis and Composites at Los Alamos National Laboratory. Or is the "Current progress" section only for "significant" new results?

[edit] Smallest Carbon Fullerene?

The mathematics section says that a 20-atom ball is the smallest mathematical fullerene. Has C₂₀ been observed? If not, what is the smallest fullerene in the non-mathematical sense that has been observed? Jon the Geek July 1, 2005 22:57 (UTC)

C₂₀ was observed spectrometrically, with identification based on the theoretical prediction of its spectrum.

References:

• Nature 407, 60 - 63 (07 September 2000)
• hys. Rev. Lett. 87, 035503 (2001)

Ed Sanville 22:25, 5 November 2005 (UTC)

I have heard that the smallest fullerene is C₂₀ but there is no C₂₂. Can someone show me that there is no C₂₂ (using MATH)?

[edit] Bond strength

Excuse my ignorance, but since when an sp² is stronger than an sp³? Don't sp³ orbitals form stronger bonds because of their larger p character? 212.201.44.249 13:48, 28 July 2005 (UTC)

In response to above comment; Bond energies in kj/mol (determined by the energy need to break the bond):

• C-(single)-C 348 sp3
• C-(double)-C 614 sp2
• C-(triple)-C 839 sp

-signed...the concerned chemist, 8/20/2005

In other words, sp² bonds are weaker than sp³ bonds, but in a double bond there is one of each. Therefore a double bond is stronger than a single bond. Ed Sanville 20:41, 27 December 2005 (UTC)

[edit] External links and sources

I wish to start the practice of showing when the External link was last updated and by whom. On fast changing technology it is a pain to re-visit a web site that has not changed since visited last. If we can keep update dates noted in this section then it may encourage the External site to stay current and updated. I have taken the liberty to do this to the first External link here. What do others think?

The Nanotube site ( I added this -> "This site last update: 2005.08.05 (Friday) 10:08:05 EDT by David Tomanek." --Bobwinmill 19:22, 12 September 2005 (UTC)

Maybe this should be discussed at a higer level, say the Village pump, as this concept could apply to lots of articles. I personally don't like it, as it clutters the page and requires constant update.

All information in Wikipedia requires constant update. That is the general idea I hope. As per clutter, if a link is just an article, that is outdated (say 2 years for Carbon nanotube) then maybe we should just eliminate the link. If this was a non-dynamic area this would not be a good idea, but here a year is a long time. Who wants to waste time going to a page with outdated information. If someone wants a historical perspective on the topic they can go into the history and archives of the topic. - Bobwinmill 11:53, 17 September 2005 (UTC)

[edit] nanotubes in mp3 players

http://www.nantero.com/mission.html says:

Possible uses include the enabling of instant-on computers, which boot and reboot instantly, as well as high-density portable memory - MP3 players with 1000s of songs...

Wow nanotubes make the ipod possible!!!

The article "Nanotechnology-based data storage on rise" also seems pretty excited about non-volatile nanotube-based memory, and mentions some of the memory types it competes against. So ... how does it work in the lab? Are nanotube-based memory chips sold commercially yet?

nanotubes do not make the ipod possible. --Rmalloy 18:05, 16 October 2006 (UTC)

[edit] Question on nanotube diameter

What is the smallest possible diameter of a carbon nanotube? - Student2

According to The Science and Technology of Carbon Nanotubes, the smallest possible diameter is around 0.7nm.

VCUchem 07:48, 24 November 2006 (UTC)

[edit] adhesion of CNT

is there any way to adhesive CNT on another surface, ie, silicon or gold. and is there any way of testing the adhesion strength after placing it on the surface? ....interested student

In response to the above, the answer is a resounding 'yes'. The method of adhesion is going to depend on your motive... for example, I recently dispersed nanotubes on TSG (Template Stripped Gold), which was as simple as dissolving nanotubes in chloroform and placing a droplet (a few microlitres) onto the exposed surface. A centrifuge handled the drying, though I believe blow-drying with nitrogen gas might be sufficient.

As far as adhesion strength goes, you are unlikely to win any prizes with this method. I can only confirm it produces a bond strong enough to survive AFM in tapping mode. For better adhesion, I would suggest using a different solvent (one which would leave behind a residue), again this may or may not be desirable depending on your motives.

Hope this helped, Jamie

In relation to attaching molecules to carbon nanotubes, I read in a paper, (Huaming Li et al, "Functionalization of Single-Walled Carbon Nanotubes with Well Defined Polystyrene Click Coupling", JACS 2005) that during the sidewall chemical modification of cabon nanotubes, in the presence of amyl nitrite as a catalyst, the p-aminophenyl propargyl ether molecule loses the amine and in its place a carbon carbon bond is formed to the SWNT at a sidewall postion. My question is... How does the Isoamyl Nitrite catalyst facilitate the creation carbon-carbon bond at the side wall postion, when it has been much better documented that chemical modification of SWNT's occurs at ends and defect sites? Mechanism perhaps? NanoLlama 17:06, 25 May 2006 (UTC)

[edit] graphitic wings

Are these "graphitic wings" worth mentioning in the article? "Flying" nanotubes are strong and hard ARGONNE, Ill. (July 16, 2004)

possibly. although it is a bit specific at the moment, as the technology advances i'm sure it will become increasingly important to include this (and many other) branches of nontube studies - mastodon 21:05, 27 March 2006 (UTC)

[edit] Health risks and toxicity

The article on Buckyballs says that they can be toxic. Does anyone know if this applies to CNTs as well?

Are there any health risks to carbon nanotubes, say like there is for Asbestos? (Small fibrous particles in the air, etc.?) zoney ♣ talk 09:46, 2 March 2006 (UTC)

The simplest way to answer your question is we don't know. Thats the answer given on Sigma-Aldrich's safety data sheet anyway. Nanotubes are very unreactive so there probably is very little toxic hazards but there may be mechanical risks with them. The best way to treat them is as a hazardous material until we know better. Afn 12:44, 2 March 2006 (UTC)

since the human body does not have a means(enzyme) do break down carbon naotudes they may be just as toxic as asbestos--taucetiman

There should be a piece in the article mentioning the concerns over health risks at the very least. zoney ♣ talk 11:15, 6 March 2006 (UTC)

One major concern is the similarity to asbestos. Although there is not a concensus on this at the moment, I have read a couple of papers from asbestos experts that say that the comparison is invalid. The danger of asbestos exists because of its "spear-like" structure. Nanotubes, on the other hand, usually exist in a knotted balls of ropes. There was also a study done where tubes were forcibly injected into the airways of mice, there were fast CNS responses, which quickly dissipated. The conclusion was that this was not do to the CNTs, but due too poor methodoloy. This study also illuminated the fact that CNTs are not really respirable, hence the forcible injection.

There are a couple situations where they know that CNTs can be toxic. It is more appropriate to say that the residual catalyst is toxic (Nickel). Nonetheless, I believe that CNTs should be treated as toxic until further study is done. Hellkyte

This would be dangerous, you cannot claim that a material is toxic simply due to its catalyst as different techniques use different catalysts. CNTs are so far shown to have had some effect on the respiratory systems of fish, but the relative effect on humans has not been shown.

Ref: E. Oberdorster, S. Q. Zhu, T. M. Blickley, P. McClellan-Green and M. L. Haasch, (Ecotoxicology of

carbon-based engineered nanoparticles: Effects of fullerene

(C{$_{60}$) on aquatic organisms, Carbon 44, 1112 (2006)

However, the field of research is still relatively young. There have also been experiments which have shown that CNT's have positive effects upon insertion into biological organisms

Ref: ICN+T 2006 Abstract Booklet. Iop Conference Series

As such, the tubes cannot be considered as toxic at the moment. This is not to say that they are 100% safe, but to brand them toxic would be a mistake.

Shepplestone 16:30, 8 August 2006 (BST)

I should have specified that nanotubes created using the Nickel catalyst method would be toxic due to residual catalyst. Anyways, I find it disturbing that you treat this material with an innocent until proven guilty attitude. If you don't know for sure, and we don't, treat it as dangerous. Of course the only people this will matter to are people working in production, as anyone outside of production will only see it imbedded into a plastic (for the most part) or carefully treated and used as a pharmaceutical. If I am not mistaken, the pharmaceutical uses only apply if the nanotubes are functionalized. Without the functionalization they are considered cytotoxic. - Hellkyte

[edit] Progress cleanup

this section is confusing. it would be much better suited as a ==history== section, from initial conception, to first sythesis, and all the significant progressions from then to the present. as of now, it is just a jumble of dates, with only chronolgical order, no metion of significance whatsoever. i think this technology has masive promise, and will therefore find itself on the front page, as it enters public conciousness. but it won't do that without a clear, consise and thougough breakdown of the material's history. perhaps it should be split into a second article (timeline of...). having said this i am no expert, having not studied them in chemistry yet. call in an expert editor! mastodon 13:45, 26 March 2006 (UTC)

[edit] 63 GPa tensile strength

Both this article and Space elevator state that the maximum measured tensile strength for SWCNTs is 63 GPa. In both cases it is inproperly referenced. This article gives a google link searching for nanotubes "tensile strength" "63 GPa", the Space elevator article states that the experiment was performed in 2000 but only gives a dead link [1] as a reference. However judging by the URL, it's likely that the paper was one of the two relevant papers published by a team including Rodney S. Ruolff in 2000 (the first author of both was Min-Feng Yu). One was Phys. Rev. Lett. 84, 5552–5555 (2000), and reported a tensile strength of 13-52 GPa for SWCNTs. The other was Science 28 January 2000: Vol. 287. no. 5453, pp. 637 - 640, which reported a tensile strength of 11-63 GPa for MWCNTs, not SWCNTs. The source of Wikipedia's confusion may well be the report published by the Institute of Space Research titled The Space Elevator, which states [2]:

The second paper that is of interest appeared in Science in January [Yu, 2000a] with a follow-up of additional measurements appearing in Physical Review Letters in June [Yu, 2000b]. In these papers, Yu presents some of the first measured tensile strengths of nanotubes. Yu and colleagues appear to have done a thorough and well thought out experiment and got impressive results. Tensile strengths of 11 to 63 GPa were measured for individual nanotubes compared to Yu's references of theoretical tensile strengths of 300 GPa. (We used 130 GPa, Yakobson and Smalley, 1997, in all of our calculations.)

Individual nanotubes indeed, but individual multi-walled nanotubes, not individual single-walled nanotubes.

I'll be amending both articles shortly unless someone can tell me about some other experiment performed in 2000 which did in fact report a strength for SWCNTs of 63 GPa. -- Tim Starling 05:41, 3 April 2006 (UTC)

[edit] Carbon nanotube tori

The article lists nanotori, and says such a structure "...has good properties". What does this mean? Good properties for what? (Carbon nanotori are, by the way, well documented and investigated, the question is which of their properties are "good", and for what.) Nahaj 14:41, 21 May 2006 (UTC)

It now appears someone deleted the entire section on Carbon nanotori, citing the "good properties" comment. Since they are a legitimate form, I've put the section back (without the silly comment about "good properties"). I added a comment about one specific property that they have (from the many in the literature), so section doesn't look totally empty. Nahaj 20:28, 21 May 2006 (UTC)

[edit] Additional info on MWNTs?

I noticed there's a good amount of detail on SWNTs, yet MWNTs are dismissed with a few lines. Down in the article, it is stated MWNTs could be used because of their higher elasticity, allowing the fibers to translate one inside the other. Are there other applications?

Another things which I would like to know is the use of nanotubes for generators. It is stated that electrical motors can be greatly improved by nanotube technology. Since generators are "somewhat" similar, I would like to know if there have been experiments on nanotube-enhanced electrical generators.

Thank you! MaxDZ8 talk 07:45, 30 May 2006 (UTC)

One of the only things I can say from experience is that MWNTs are a LOT easier to grow. Hellkyte

[edit] Applications

Question: How are carbon nanotubes used as field emitters in electron beam sources?

The applications section is atrociously made. There exists a lack of capitalisation and a good description on why they are appropriate for this role. AllStarZ 20:34, 30 May 2006 (UTC)

The following statement under the application line should DEFINITELY be sourced, because this is a HUGE claim.

Carbon nanotubes have also recently been discovered to be a component of damascus steel (ancient swords made from it were reported to have been able to cut through stone and metal without losing their edge, and could still cut silk scarves in mid-air).

-Hellkyte

There is a source given in the Damascus steel article: Sharpest cut from nanotube sword. However, the Damascus steel article says that the claims about cutting through stone and steel are apocryphal. Itub 01:41, 16 January 2007 (UTC)

[edit] 1993 Discovery of single-wall carbon nanotubes

Added to nanotube timeline:
ft 1993

• Groups led by Donald S. Bethune at IBM and Sumio Iijima at NEC independently discover single-wall carbon nanotubes and methods to produce them using transition-metal catalysts.

Discussion:
These discoveries [1,2] at IBM [3] and NEC marked a significant turning point in carbon nanotube research, since the catalytic routes found for the specific production of single-wall nanotubes led to an explosion of research on them. In 2002 the American Physical Society awarded Bethune and Iijima the The James C. McGroddy Prize for New Materials [4] "For the discovery and development of single-wall carbon nanotubes, which can behave like metals or semiconductors, can conduct electricity better than copper, can transmit heat better than diamond, and rank among the strongest materials known." and in 2004 the American Carbon Society Medal [5] was awarded to Bethune, Iijima and Prof. Moribundo Endo (Shinshu University) for "outstanding contributions to the discovery of, and early synthesis work on, carbon nanotubes". Dsbethune 23:20, 30 June 2006 (UTC)

[1] D.S. Bethune, et al., Nature 363, 605-607 (1993).[6]
[2] S. Iijima and T. Ichihashi, Nature 363, 603-605 (1993).[7]

---

The discovery of nanotubes is still a debatable subject and to maintain neutrality Wikipedia should not state who is responsible for their discovery at the present moment. An excellent review is provided in Carbon 44, 1621 which shows claims dating as early as 1952. The importance of Iijima's report may not be the discovery so to speak, but it was the report which brought carbon nanotubes to the attention of the scientific community as whole.

Shepplestone 14:25 17 January 2006 (GMT)

[edit] Synthesis

I expanded the synthesis section a bit. I felt it deserved some more attention. If I have paid too much attention to CVD it is only because I know the most about that particular method. If anyone would like to change my references to DOI links that would be great.

--147.226.171.199 20:07, 13 July 2006 (UTC)

Awesome! Thanks, whoever you are. —Keenan Pepper 20:19, 13 July 2006 (UTC)

[edit] Ballistic conduction

Ballistic conduction is listed as a thermal property, but the link points to an article describing it as electrical.--128.154.44.44 14:22, 19 July 2006 (UTC)

The term Ballistic conduction is correct, but the link is incorrect, I am searching for an appropriate link at the moment. User:Shepplestone:Shepplestone 16.28 8 August (BST)

[edit] Nanotubes in flames?

This article currently says, "Fullerenes and carbon nanotubes are not necessarily products of high-tech laboratories; they are commonly formed in such mundane places as candle flames." Is it true that nanotubes can be found in candle flames? After a fair amount of searching, I have found references saying that buckyballs are found in candle flames, but nothing about nanotubes. Can someone provide a reference? If not, perhaps this statement should be deleted. —The preceding unsigned comment was added by 134.76.218.117 (talk • contribs) .

I added four references that say they're all over the place. I'm convinced they're produced in candle flames, but none of the references specifically mention candles, so that would be OR. Hmm, now I think I'll work on Soot... —Keenan Pepper 08:08, 17 August 2006 (UTC)

[edit] superconducting nanotubes

Does anybody have a reference for the alleged superconductivity of carbon nanotubes? I am aware of experiments with superconducting leads and claimed intrinsic superconductivity. As far as I know however it is still controversial whether carbon nanotubes by themselves are superconducting. -- Bamse 09:38, 6 September 2006 (UTC)

[edit] GA Review

GA review (see here for criteria)

1. It is well written.

   a (prose): b (structure): c (MoS): d (jargon):

2. It is factually accurate and verifiable.

   a (references): b (inline citations): c (reliable): d (OR):

3. It is broad in its coverage.

   a (major aspects): b (focused):

4. It follows the neutral point of view policy.

   a (fair representation): b (all significant views):

5. It is stable.

   

6. It contains images, where possible, to illustrate the topic.

   a (tagged and captioned): b (lack of images does not in itself exclude GA): c (non-free images have fair use rationales):

7. Overall:

   a Pass/Fail:

• The article are overusing abbrevations, see Wikipedia:Manual of Style#Acronyms and abbreviations

Removed a lot of the abbreviations Snailwalker | talk 11:06, 21 October 2006 (UTC)

• The section "Types::Single-walled" have some Harvard citations, but the rest of the article have Chicago types. Also it mixes up air and oxygen. It lacks reason why for example n=0 results in zig-zag etc.

I don't see how it lacks reasons for n=0 results in zig-zag, it's just a definition that they're called zig-zag, because they kind of look like zig-zag, one can also see it on the image Snailwalker | talk 10:56, 21 October 2006 (UTC)

• In the section "Discovery", it says that it have a one-dimensional structure, but no where in the article it specifies this one dimensional structure, and all images shows a three dimensional structure, it's really confusing.

Removed as there was no reference and as far as I know CNT's are three-dimensional structures Snailwalker | talk 11:06, 21 October 2006 (UTC)

• The section "History" should be removed and be replaced by a see also link.
• Wording like "Perhaps the best hope" is a violation of NPOV
• Section "Potential Applications::In electrical circuits" lacks references.

This I feel is too much to be fixed in one week, so I'll fail the nomination. _→AzaToth 16:25, 16 October 2006 (UTC)

Okay thanks for the review, I'll look into it and probably nominate it again some other time! Snailwalker | talk 08:34, 17 October 2006 (UTC)

[edit] Synthesis

Can they really make these in an anus, or is this the work of a vandal? I do like the title Analtubes for Tomorrow though. —The preceding unsigned comment was added by 66.73.14.2 (talk) 16:39, 8 December 2006 (UTC).

it was vandalism and i removed the edit. a friend of mine did it as an experiment in seeing how long it takes for errors to be fixed in wikipedia. it was a stupid thing to do and now i'm going around and finding his edits and reverting them. some people just don't appreciate wikipedia. Bdean42 16:51, 8 December 2006 (UTC)

[edit] Mislabelled, misplaced Illustration?

The illustration with the caption "The joining of two carbon nanotubes with different electrical properties to form a diode has been proposed" highlights an instance of a heptagonal formation of carbons with a pentagonal, which was mentioned earlier in the article as a category of defect in nanotubes. If the method of joining nanotubes with different electrical properties, requires exploiting this defect ("bugs as features?") then the caption should be reworded; but I suspect it's just mislabelled and misplaced. Peter H. St.John, M.S. 20:44, 8 December 2006 (UTC)

[edit] "In electric circuits" - completely outdated

This section is outdated to such a degree that it would basically have to be rewritten from scratch. It is based on the state of the field in 2000 and quite a lot has happened since then. In 2001 the first nanotube transistors operating at room temperature was made. The same year, IBM demonstrated a circuit with 1000 nanotube transistors. In 2003 a single-chip waver with ten billion nanotube transistors was created. In 2004 researchers at UCLA created a working integrated memory circuit based on nanotubes - that also demonstrated a fully automated method of removing failed nanotubes.. etc

The things above are just a few things that I saw listed in Ray Kurtzweil's 2004 book "The singularity is near". Given the exponential development of these things, it is safely to assume that between 2004 and now there have been as many breakthroughs as between 2000 and 2004.

I'm reluctant to write anything about it as I know very little of the field - it would be good though if we could get somebody to update the text to reflect the developments since 2000. --Denoir 19:16, 27 December 2006 (UTC)

• I would second that. Ergzay 20:30, 21 January 2007 (UTC)

Well, you should see what the text looked like before - I updated it to 2004 standards. I'm sure however a lot has happened since 2004, exponential progress and all. --Denoir 22:00, 21 January 2007 (UTC)

[edit] GA Review 2

I'm making notes as I review the article for GA. Please feel free to start addressing these at any time, either by explanation here or by editting the article.

1. It would be helpful if chemical bond were included in the proce of the lead so readers don't have to go to Sp2 if they don't know that Sp2 and Sp3 are types of chemical bonds.
2. First instance of graphene is not wikilinked.
3. Why no reference citation for the 1952 Radushkevich and Lukyanovich paper?
4. Some citations (E.g. 2 and 5) occur in the middle of a paragraph. What about the rest of the paragraph - is it covered by the same reference or is it uncited? If it is covered by the same reference you should move the reference to the end of the paragraph. #"The discovery of nanotubes remains a contentious issue, especially because several scientists involved in early nanotube could be likely candidates for the Nobel Prize." - does not sound grammatically correct to me. #Carbon 44, 1621, 2006. - cite in same style as other references #Single-wall section - I made it through this section, but it took some work. Can it be made any easier? By comparison, the multi-walled section is much easier to read. #"Single-walled nanotubes are still very expensive to produce,..." - could you quantify this? At least roughly?
5. (0,8) single-walled nanotube - does that mean 8/10 of a nanometer? Or does that refer back to the (n,m) terminolog of the graphene sheet? I don't think this notation has been introduced for the nanotubes itself. This nomenclature should be explained please.
6. The interlayer distance is close to the distance between graphene layers in graphite - which is how much? Is this true for both Russian Dolls and Parchment?
7. "...while improving significantly their chemical resistance." - what is "chemical resistance?
8. Tourus - "many" is un-needed
9. Properties section - very good! Very easy to read.
10. Defects - needs more references
11. "Some defect formation in armchair-type tubes (which are metallic) can cause the region surrounding that defect to become semiconducting." I don't understand this sentence. Is it trying to say armchair-type tubes (as opposed to zig-zag type tubes) are metallic? How is that so since they are both carbon?
12. Please look for additional wikilinks that could be added. Some suggestions: centimeter, vacuum, amp, microscopic, macroscopic
13. Of the various means for nanotube synthesis, CVD shows the most promise for industrial scale deposition in terms of its price/unit ratio. - this paragraph needs a citation
14. There is a citation-needed tag in the article that needs addressing
15. (The Space Elevator, by Brad C. Edwards, NASA) - cite like the other in-line sources, please.
16. Nanoelectromechanical Systems (NEMS) section is very short. Can it be expanded or else merged somewhere else?
17. Nice images!
18. Generally good references but some (2, 4, 6, 10, 53,...) are not in the same style as the others. I recommend using {{cite web}}, {{cite journal}}, etc.

I think it is a nice article. A little difficult at times perhaps. Informative definitely. A few issues as noted above. If you think you can tackle all or most of these leave me a message and I will come by to take another look. A word of warning - I tried to be thorough the first time through but I reserve the right to make additional comments on a second pass if they jump out at me. Good luck and please keep up the good work. You are almost there and Wikipedia needs more good articles on important topics such as this. Johntex\^talk 06:00, 25 January 2007 (UTC)

This article should NOT get GA. Its not that the stuff put here isn't correct, or well written. Its more that the subject itself is so early in development that its not a stable science at the moment. For example, I just heard about the first ISO for nanotube analyticals coming out in rough draft form. No one really knows that much about defined metrics surrounding the material, at best their metrics are simplistic (raman) or unidentified/proprietary. That's a baby as far as I am concerned.

What this leads to is a mixture of audience of professionals interested in the science, and hobbyists interested in the science. And there is nothing wrong with that, nanotubes very well may change the face of materials science in the next decade. But it means that it exists in a void where there is a lot of pop-science style information (aka sexy, but not really important, like Paris Hilton), and not a lot of the really important information, some of which is being protected at the moment by the people that have discovered it, or simply not known.

In response to some specifics that you labeled, as these can for the most part be adressed.

1) Not sure what "proce lead" means, so what I say may be inferring the wrong thing from your request. I think that this article has two types of readers, professionals and hobbyists. A professional chemist should know instantly what Sp2 means. A professional engineer should have the desire to look it up, because its important to understand it, and engineers are nothing if not link clickers. Hobbyists may just want that to say "chemical bond" but you have to ask who this is for? When it comes to scientific topics for work the first place I check is wikipedia, then I move on from there. I think most scientists will agree that they want pure unadulterated information, much like you have on things like "heat capacity" or "bulk density". I appreciate the desire for accessibility for hobbyists, but its not that hard for them to figure out what Sp2 is, and really its not that important (for them). If we were to take every scientific term in a wiki article and define it, their practical usefulness to scientists would be non-existent. That is my overlong reasoning for saying "no".

5) From the papers I have read its standard to read it as (n,m). I'm not exactly sure how you could derive a fractional diameter from that.

6)For the first question see 1. Its not hard to look up. The second question, however, I think definitely needs to be answered.

11) This issue has a lot to do with what is so difficult about nanotubes in general. Molecules of this size almost never exist, and when they do (like proteins), they aren't homogenous, and almost entirely structurally identical. Basically this is an entirely new field of chemistry (hence the Nobel Prizes). This is why you can have things like a partially metallic, partially semi-conducting molecules. Its not the atomic makeup that defines their difference, its the structure, which is so large, and so varied from tube to tube, that they are damn near impossible to define isomerically like you could some small organic. This is something I am not entirely clear on, but I hope I answered your question by the situation more confusing.

15) This is in a pop-mechanics article. I will post a citation here tommorow when I find it, its in my office somewhere.

I hope this helped somewhat. Some of my answers are POV (like gear it more towards professionals). I wish you good luck on this -Hellkyte

[edit] GA failed

It's been in excess of the 7 day maximum that the GA nomination was put on-hold and issues relating to the original reviewer's comments still exist. Please re-read his commentary and the comments left by others, and use it as constructive criticism to improve upon the article. Do try again when you have everything sorted. Nja247 (talk • contribs) 16:38, 8 February 2007 (UTC)

[edit] Thermal

The melting point given appears low. This article says

"The temperature stability of carbon nanotubes is estimated to be up to 2800 degrees Celsius in vacuum and about 750 degrees Celsius in air."

The Carbon pages says

"At atmospheric pressure it has no actual melting point as its triple point is at 10 MPa (100 bar) so it sublimates above 4000 K. Thus it remains solid at higher temperatures than the highest melting point metals like tungsten or rhenium, regardless of its allotropic form."

The two articles need reconciling. Either the same temperature needs giving or possibly a description of the effects of temperature instability. Andrew Swallow 19:11, 30 January 2007 (UTC)

You are talking about apples and oranges. Comparing elemental carbon and carbon nanotubes is like talking about soot and diamond. They are massively different.

Plus the listed thermal stability is not the melting point, its the chemical stability, meaning that you can burn tubes @750C. Which isn't even correct. Nanotubes burn/oxidize over a wide temperature range based on structure, which includes but is not limited to 750C. I also definitely believe that any specific temperature about the melting point information about nanotubes is highly proprietary at the moment.

Also, I seriously question making a generalized statement about the power transmission capabilities of nanotubes. Yet again, this is dependent on structure. -Hellkyte

[edit] The "one-dimensional" nonsense is back

The GA review said that needed to go, it's back, and hmm, the article failed GAC. The gist: If it's a tube, that by definition means it is three-dimensional, even if I'd need one heck of a miscroscope to actually look inside a real one. — SMcCandlish [talk] [contrib] ツ 10:15, 2 March 2007 (UTC)

Maybe you are taking "one-dimensional" too literally. It is one-dimensional in the sense that it only grows to arbitrary lengths in one direction. Similarly, people sometimes refer to graphite sheets and similar structures as "two-dimensional", despite them having nonzero thickness. Itub 12:38, 5 March 2007 (UTC)

See for example all the scientific articles found by Google Scholar that refer to nanotubes as "one-dimensional". [8] --Itub 12:43, 5 March 2007 (UTC)

One of the main goals of Wikipedia is clarity. Obviously, CNTs are not literally one-dimensional, any more than an atom is zero-dimensional. However, they are so tiny on the two dimensions perpendicular to their length that they are "practically" one-dimensional - at the least, they are the closest thing to a real, physical, one-dimensional object observed to exist (afaik). This quality is, in itself, interesting and perhaps worth mentioning in the article, but care should be taken to avoid confusion. You suggest McCandlish is being too literal, but the info on wikipedia should be literally true, or the criteria and context in which it is true must be made clear. To simply say that nanotubes are one-dimensional, even with the vague qualifier "essentially," is potentially misleading to the less scientificly literate audience. Perhaps less objectionable would be something like this (new text in italics):

Carbon nanotubes (CNTs) are allotropes of carbon. A carbon nanotube is a one-atom thick sheet of graphite (called graphene) rolled up into a seamless cylinder with diameter of the order of a nanometer. The extreme length-to-diameter ratio, which can exceed 10,000:1, results in a structure which is macroscopic in only one dimension. Such cylindrical carbon molecules have novel properties that make them potentially useful in a wide variety of applications in nanotechnology, electronics, optics and other fields of materials science. They exhibit extraordinary strength and unique electrical properties, and are efficient conductors of heat. Inorganic nanotubes have also been synthesized.

I think this version would be more factually correct, and might satisfy both sides, but I'd still question if the point is worth making at all. It's a bit interesting, perhaps, but it also seems a bit obvious, and it's a bit of a logical dead-end. Goph42 20:44, 23 March 2007 (UTC)

Maybe a better wording would be to say "they have a large length to width ratio" instead of saying one-dimensional. Ergzay 00:08, 26 March 2007 (UTC)