Follow Slashdot stories on Twitter

 


Forgot your password?
Close
typodupeerror
×
Science Technology

Another Form of Carbon: Magnetic Nanofoam 38

Posted by timothy from the foamy-goodness dept.
mhh5 writes "Researchers publishing in Nature have discovered yet another form of carbon. Apparently, this stuff is temporarily magnetic after it is made (at temperatures of ~10,000 C) and is a spongy solid. So that's five (give or take one?) allotropes for carbon: amorphous, graphite, diamond, fullerenes, and nanofoam. Collect them all!"
This discussion has been archived. No new comments can be posted.

Another Form of Carbon: Magnetic Nanofoam More

Another Form of Carbon: Magnetic Nanofoam

Comments Filter:

  • Injecting into my bloodstream? (Score:2, Interesting)

    by Anonymous Coward
    This is really cool--another form of carbon.

    But the linked article discusses injecting this into people's bloodstream for imaging purposes.

    I know that nothing of the sort would happen until after extensive testing, but the thought of it makes me cringe. Injecting it into my bloodstream is bad enough, but doing that and then subjecting it to a strong magnetic field--which it is extremely responsive to--seems especially troublesome.

    I'm not saying that it wouldn't be useful. I'm just saying it makes me conc
    • Well, unless this form of carbon is unusually reactive, or acts like asbestos (a "physical toxin"), it would likely just break down into carbon in the bloodstream and be absorbed or eliminated like the CO2 in our breath.
    • Can I guess you are opposed to MRI's too? My grandfather, a veteran of WW II couldn't have MRI's because in gaining his two purple hearts, he also got shrapnel lodged in his skull, which because it could become dislodged in an MRI, he couldn't have. About a year ago, he had some hemoraging in his brain, and they had to basically go in blind to releave the preasure. Oddly enough, he outlived his brain surgeon, who died of a heart attack soon thereafter, although he followed himself in October. Such is li
    • I'm not worried about having magnetic substances injected into my bloodstream - I get enough EM radiation from my PC's monitor, not to mention sunlight. What I'm curious about is the article's discussion of heating the molecules once they're inside my body. I know one of the researchers mentioned that this carbon nanofoam is a piss-poor conductor of heat, but I'm still a bit wary of that.

      Also, it's been a few years since high-school chemistry - why would this nanofoam lose its magnetic properties after a

      • Re:Injecting into my bloodstream? (Score:4, Informative)

        by JGski ( 537049 ) on Wednesday March 24, 2004 @02:38PM (#8658786) Journal
        That this nanofoam loses its ferromagnetism with time suggests that nanofoam is fundamentally unstable at the molecular level. Presumable its ferromagnetism is due to a separation of the electron orbits between adjacent atoms caused by being in a "foam". Like a soap or detergent foam, it presumably breaks down over time resulting in the condensation of the carbon atoms back into a normal non-magnetic separation. I haven't read the original paper so this is just an educated guess.
    • Injecting it into my bloodstream is bad enough, but doing that and then subjecting it to a strong magnetic field--which it is extremely responsive to--seems especially troublesome.

      You mean like cooking food with strong electromagnetic radiation seems especially troublesome?

      Are you afraid that the highly magnetic nanofoam in your bloodstream might suddenly be torn from your veins when the magnet malfunctions?

      Hate to break it to you, but X-Men isn't real! :)

  • My wife... (Score:4, Funny)

    by rthille ( 8526 ) <web-slashdot@ran g a t .org> on Wednesday March 24, 2004 @12:43AM (#8652995) Homepage Journal
    gets all the diamonds we can afford you insensitive clod!

  • Finally... (Score:4, Funny)

    by ebrandsberg ( 75344 ) on Wednesday March 24, 2004 @12:46AM (#8653009)
    A new form of carbon that wasn't predicted by SciFi!

    • Re:Finally... (Score:3, Interesting)

      by stevelinton ( 4044 )
      Nonsense -- sounds remarkably like a primitive version of the "flamed trellis" from A Fire Upon the Deep:


      After a moment, Greenstalk said a little shyly,
      "There are theories. It's pure carbon, a fractal polymer. We know it's very
      common in Transcendent cargoes. We think it's used as packing material for
      some kinds of sentient property."
      "Or perhaps the excrement of such property," Blueshell buzz-muttered.

  • Nanotubes (Score:2, Interesting)

    by isn't my name ( 514234 )
    So that's five (give or take one?) allotropes for carbon: amorphous, graphite, diamond, fullerenes, and nanofoam. Collect them all!"

    Don't nanotubes make at least six? Or are you considering that a weird fullerene form?

    • Re:Nanotubes (Score:5, Informative)

      by dnahelix ( 598670 ) <slashdotispieceofshit@shithome.com> on Wednesday March 24, 2004 @01:45AM (#8653330)
      fullerene
      n.
      Any of various cagelike, hollow molecules composed of
      hexagonal and pentagonal groups of atoms, and especially
      those formed from carbon, that constitute the third form of
      carbon after diamond and graphite.

      Diamond, Graphite and Fullerene forms are crystalline, the amorphous forms are coal, coke, charcoal, lampblack, gas carbon etc.

      In diamond, each C-atom is covalently bonded to four other C-atom to give a tetrahedral unit. In diamond each C-atom is sp3-hybridized.Therefore each C-atom forms four sigma bonds with neighbouringC-atoms. In diamond C-C-C bond angle is 109.5 degrees.These basic tetrahedral units unite with one another and produce a cubic unit cell.

      In graphite each C-atom is covalently bonded to three C-atom to give trigonal geometry. Bond angle in graphite is 120 degrees. Each C-atom in graphite is sp2-hybridized. Three out of four valance electrons of each C-atom are used in bond formation while the forth electrons free to move in the structure of graphite. Basic trigonal units unite together to give basic hexagonal ring. In hexagonal ring C-C bond length is 1.42A degrees. In graphite these rings forms flat layers. These layers are arranged is parallel ,one above the other. These layers 3.35A degrees apart and are held together by weak van der waals forces only.These layers can slide over one another.Thus it is very soft. Fourth electron of each c-atom forms delocalized p-system.

      During the irradiation of diamond by atoms, many bonds are broken, leading to point defects and eventually to clusters of defects. At a high enough irradiation dose, amorphization of the crystal structure may occur and two specific amorphous forms of carbon may appear: the tetrahedrally bonded Diamond-like Amorphous Carbon which will be denoted by ta-C and the sp^2 bonded Graphite-like Amorphous Carbon named a-C. These two structures can be distinguished clearly by their macroscopic and microscopic properties. The former material has higher density, is transparent, electrically insulating and much harder than the latter. From the microscopic point of view, the ratio of fourfold, diamond-like bonds to threefold, graphite-like bonds (sp^3/sp^2) determines the kind of structure obtained.
      • Showoff :)

        I just did a report for my Engineering and Architectural Design concerning the use of carbon-nanotubes.... and not one single person, student or faculty, had ever heard of them. This is wholly depressing, BUT afterwards several students and a few teachers came to talk to me privately about it, and ask for more information.

        Does anyone else think that scientific news actually DESERVES and NEEDS to be heard by the general populace? Even if they don't get it, they'll still know about it. Hell, mos
      • Hypothesis:

        Fullerenes are crystals in the same sense that
        a benzene ring is a crystal. I.e., not
        according to any familiar definition of "crystal":

        Basis:

        Every nomenclature use of "crystal" in my
        experience requires an unlimited tiling geometry.

        Plan:

        Please correct any errors above with statements
        of facts or references to facts.

      • Man, do I feel like Algernon now. I *know* that I once knew this stuff back and forth, and it all looks familiar and makes some semblance of sense, but I can't put specific meaning to much of it. :: cries ::

        Maybe I'll add in a chem review class in next semester's schedule.

    • Re:Nanotubes (Score:2, Informative)

      by Xilman ( 191715 )
      You will find that so-called amorphous carbon is really just graphite, but in very small particles. It's not really an allotrope in its own, more microcrystalline form of another.

      Paul

  • Could this be used as a thermal blanket for the next generation re-entry vehicle?
    • Seeing as its a foam, which is inherently weak in comparison to nanotubes or buckyballs, I wouldn't think so. I would expect that a fabric or other material made from carbon nanotubes would be a much more likely replacement for the ceramic tiles that spacecraft currently use for re-entry.

    • Re: (Score:2, Insightful)

      by account_deleted ( 4530225 )
      Comment removed based on user account deletion
      • And is brittle as all hell.

        I have a small piece (well, several small pieces now) of monolithic (slab) aerogel about 20mm thick that I got as a sample from a manufacturer. When I took it from the case, I marveled at its texture (feels dusty without being so) and the translucence, knowing of the various thermal properties. Within about 30 seconds, though, it had broken in two even though I was handling it with the utmost care. It broke again when the case fell from a shelf about five feet up onto *carpet*
    • Like other forms of carbon, it's probably flammable.
  • My Electronics teacher just told us to write a paper on the Buckyballs, so it is cool to have some info to trump him with for tomorrows class (paper is due tomorrow).

  • Other links (Score:5, Informative)

    by cagle_.25 ( 715952 ) on Wednesday March 24, 2004 @08:17AM (#8654653) Journal
    The article was egregiously low on detail. (Googles a bit...) Here is a more technical article [arxiv.org] that explains the magnetism as a result of temporary unpaired electron spins (surprise!). The magnetism occurs at temperatures below 90K, so it's fairly remarkable that they can jerk this stuff from 9700K down to 90K and have it not shatter!

  • supercapacitors? (Score:3, Interesting)

    by GigsVT ( 208848 ) on Wednesday March 24, 2004 @09:21AM (#8654947) Journal
    I know they're using carbon aerogels to make really large capacitance caps in the 1-100Farad range. Does this new nanofoam have similar potential for making new capacitors with higher surface area/mass ratios?
    • A lot of supercapacitor research uses activated carbon, which can have specific surface areas in the range of 50-1500 m^2/g. Activated carbon is basically charcoal heated in the absence of oxygen, which leaves a really porous structure. And it's super cheap. Not sure about carbon aerogels though.

  • Oooh I've got a use! (Score:4, Interesting)

    by kippy ( 416183 ) on Wednesday March 24, 2004 @10:57AM (#8655931)
    I already commented on this over here [chemslash.com] but hey...

    I'm a space nut so you can guess where I'm going with this.

    Aerogel [nasa.gov] is a really cool substance. It's glass foam that's very very light and it's an excellent insulator. I don't know about it's radiation blocking properties though.

    If this carbon foam is of comparable weight as aerogel (negligible), it's perfect for space use. The lighter the better since it costs $thousands/kilo to get stuff off the ground. If it blocks radiation, fantastic. Water and metal are the big rad blockers now but they're heavy. If it can act as a good insulator too, you're golden. If not, a sandwich of aerogel and carbon nanofoam could act as a heat trapper so you don't freeze and a radiation blocker so you don't get zapped. And all for practicaly no weight. Shazam!
    • dont you need a lot of density (the denser the better) to block radiation?

      if they call it foam, it cant be THAT dense...
      • I guess it depends but I'm just going with what the article says.

        The only thing I can think of is that the structure of the foam is such that it deflects radiation in such a way that it just turns it into heat as it bounces around within its structure.
        • I guess it depends but I'm just going with what the article says.

          The only thing I can think of is that the structure of the foam is such that it deflects radiation in such a way that it just turns it into heat as it bounces around within its structure.

          Virtually all shielding mechanisms for high-energy radiation just boil down to charged particles or high-energy photons scattering off the electron coulds (exception is neutron radiation, which scatters off of nuclei only).

          While resonances cause exception

      • Re:Oooh I've got a use! (Score:4, Interesting)

        by JGski ( 537049 ) on Wednesday March 24, 2004 @02:49PM (#8658913) Journal
        "Radiation" is many, many things. It's sort of like glomming all programming languages together: OO, functional, etc.

        So blocking "radiation" isn't always simply a matter of density, aka Hi-Z shielding. There are cases, such as with cosmic rays, where Hi-Z actually increases the radiation exposure on the other side of the shield though the processes called spallation and bremstrahlung.

  • So, diamonds AREN'T forever... (Score:3, Interesting)

    by dpbsmith ( 263124 ) on Wednesday March 24, 2004 @12:03PM (#8656731) Homepage
    ...I spotted a factoid I hadn't known in the referenced Wikipedia article [wikipedia.org]

    "The transition [from diamond] to graphite at room temperature is so slow as to be unnoticeable."

    So, diamonds aren't forever, diamonds are just a really long time.

Slashdot Top Deals

I have hardly ever known a mathematician who was capable of reasoning. -- Plato

Close