Talk:Aggregated diamond nanorod

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Untitled[edit]

The first commenter really nailed this topic on the head. Dubrovinskaia, et. al. has not shown that Aggregate Diamond Nanorods are anything other than nano sized polycrystalline Diamond (aggregated in rod shapes). As the first commenter suggested, this should NOT be considered a NEW material. Dubrovinskaia, et. al. show in another paper that nano sized c-BN (cubic boron nitride) is at least as hard as diamond. They suggest (along with other sources) that smaller particle sizes = stronger material. This is exactly what their paper on Aggregate Diamond Nanorods shows. They most likely made nano sized diamond and not a new allotrope of carbon. 8/28/08

Not going to put a ton of effort in to this. But just a question, the elastic modulus of diamond is 1141GPa. Never actually used the bulk modulus before, but it seems somewhat specious to me that the bulk modulus would be 3x *lower* than the elastic modulus, why would the material behave more compliantly under more constrained loading? Also how do you actually do this test, if the material is so hard, what is physically there measuring these properties, it looks to me like it might be a machine compliance issue yielding lower values... Maybe someone with more time, or more mechanical properties experience could figure it out. —Preceding unsigned comment added by 70.137.185.190 (talk) 05:18, 12 June 2008 (UTC)

I think the figure of the diamond anvil should be replaced - this one has some stuff that clearly has nothing to do with diamond nanorods ("sample from the earth's crust.. what?"); it's confusing. -Scott , 2/28/08

--- —Preceding unsigned comment added by 128.101.156.247 (talk) 19:17, 28 February 2008 (UTC)

It would be better to say that this substance was "synthesized" rather than "discovered" since there is no evidence that this material occurs naturally.

--- Why does this link to a Wikipedia article in a different language? -Sprited Spheniscidae

Good question. I'm turning it into a local link, if an article is written about it then an interwiki language link can be placed there. Bryan 00:37, 8 December 2005 (UTC)


I find this content strange. If it's amorphous it's not an allotrope of carbon (by definition). If on the other hand it isn't amorphous then it is just diamond (albeit with small (nanosized) grains, a known ultrahard material). Also rather than link to the slashdot comments of someone called 'h4x0r-3l337' wouldn't a citation to a peer reviewed journal article be more appropriate?

Closest thing I can find is this: theoretical stuff I have a hard time understanding Browb3aten 01:50, 11 August 2007 (UTC)

After reading this forum, there should be no questions on my revisions on 18-Jan-2009 NIMSoffice (talk) 07:35, 18 January 2009 (UTC)

  • Nanorods, not nanorod - it is a polycrystalline aggregate rather than separate rods. Actually, columnar growth of poly or nanocrystalline diamond grains has been observed for ~20 years in CVD growth of diamond.
  • Not a new allotrope of carbon - the lattice structure is of diamond
  • The applied HPHT process is known for decade - no discovery here. Other groups were experimenting with compressing fullerite and reported extreme hardness of the products well before 2005.

How to test?[edit]

Reference 1 says "Subsequent experiments, carried out by loading a diamond anvil cell with both single crystal diamond and ADNR material, in order to directly compare their behaviour under static load..." which brings up the question, how do you use a diamond anvil cell to test a material that is harder than the diamond anvil cell? It seems like the diamond anvil cell would deform before the aggregated diamond nanorod sample would. Guy Macon 18:27, 20 May 2010 (UTC)

Same way you use it to examine anything else - the diamonds are deforming under high pressure anyway. I would not be surprised if their anvils are prone to irreversible deformation even below half a megabar or whatever depending on sample geometry, and I would want some very careful analysis of quasi-hydrostaticity before I would believe any high pressure structures, but the reported result looks solid from here. - 2/0 (cont.) 22:22, 20 May 2010 (UTC)
(ec - never expected, on this article :) Both would compress, making the measurement non-ideal, but they probably took that into account (the difference in hardness is not that large). Also, as I understand, the measurement was comparative - loading ADNR and then diamond. Materialscientist (talk) 22:26, 20 May 2010 (UTC)
Yes, yes, this is not a forum for general discussion - we can move to my talk if this goes too far off topic. I think that the degree of deformation in the anvils would only matter if for some reason they cared about translation distance along the compression axis (nanoindentation, for instance). As long as they have a believable pressure standard and reason to expect it to be homogeneous across both samples, they should be fine. Taking a shot in the dark here, I am guessing 600 um flats, no more than ~10 GPa (lower than their pressure medium freezes out, at any rate), and pressure directly from the single crystal sample, cross-referenced for texturing indicative of non-hydrostaticity. - 2/0 (cont.) 00:31, 21 May 2010 (UTC)
Actually, the question is not off-topic at all and WP:NOTFORUM does not apply. The question relates to the statement in the article that "aggregated diamond nanorods have a modulus of 491 gigapascals (GPa), while a conventional diamond has a modulus of 442 GPa." As a Wikipedia editor without expertise in materials science, I expected that the answer from someone more knowledgeable to either be that there is no problem (and thus no change to the page is needed) or that the testing method really is a bit dodgy (and thus I need to look for reliable sources that would justify a paragraph about difficulties measuring the hardness of something that is harder than any of the measuring tools). Either way, my goal was/is improving the article, not just a general discussion about the subject of the article. Guy Macon 10:51, 21 May 2010 (UTC)
Your concern is valid, merely because measurements of extreme hardness are never easy. I do not believe the last digit in these values (too accurate), but otherwise AGF the measurements, as I know the authors (by their work) as good specialists in this area. Materialscientist (talk) 11:10, 21 May 2010 (UTC)
Sorry, Guy Macon, I meant that my comment was wandering a bit away afield - your question was a good one. - 2/0 (cont.) 13:31, 21 May 2010 (UTC)

"Nanodiamond" circuitry[edit]

this article from vanderbilt university describes making various computer circuits out of nanodiamond, but their manufacturing process for the diamond seems different. This seems to be an important breakthrough, but i dont know if it belongs here, or at another article.Mercurywoodrose (talk) 02:50, 8 August 2011 (UTC)

Not a breakthrough but a routine progress report (media-oriented) on a topic which has been explored by many dozens groups around the world. Yes, the synthesis process is very different - HPHT compression in this article and chemical vapor deposition in the report. Materialscientist (talk) 03:13, 8 August 2011 (UTC)

A picture comparing the structure of regular diamonds with this would be good[edit]

IMO it would be good to have in the article a picture comparing the structure or regular diamonds with this variant's. --TiagoTiago (talk) 06:06, 13 August 2013 (UTC)