[Dean's World] Dave Schuler: Materials

[notify at powerblogs.com]

Posted by Dave Schuler:
Materials
http://www.deanesmay.com/posts/1187701462.shtml


   A couple of stories about interesting, new materials caught my eye and
   I thought I might pass them along.

    The lightest solid

   [1]Brick supported by aerogel 

   In the picture above a 2.5kg brick is supported by 2gm worth of
   [2]aerogel. Aerogel, which is formed by a process somewhat similar to
   freeze-drying by removing the water from silica gel and replacing it
   with gas, in this case probably carbon dioxide, has been around since
   the 1930's. It was first produced to settle a bet. The original
   version of the substance was too brittle to be useful for much but
   developments in its production has resulted in a product which is not
   only extremely light (1,000 times less dense than glass) but very
   strong and resistant to heat and cold.

   Applications that have been suggested include use as a building
   material which would be resistant to fire or blast, as armor, and for
   use in sporting equipment. Its absortion properties would make it
   useful to mop up oil or other toxic spills.

     Aerogel is also being tested for future bombproof housing and
     armour for military vehicles. In the laboratory, a metal plate
     coated in 6mm of aerogel was left almost unscathed by a direct
     dynamite blast.

     It also has green credentials. Aerogel is described by scientists
     as the âultimate spongeâ, with millions of tiny pores on its
     surface making it ideal for absorbing pollutants in water.

     Kanatzidis has created a new version of aerogel designed to mop up
     lead and mercury from water. Other versions are designed to absorb
     oil spills.

     [#133;]

     Scientists say that because it has so many millions of pores and
     ridges, if one cubic centimetre of aerogel were unravelled it would
     fill an area the size of a football field.

     Its nano-sized pores can not only collect pollutants like a sponge
     but they also act as air pockets.

     Researchers believe that some versions of aerogel which are made
     from platinum can be used to speed up the production of hydrogen.
     As a result, aerogel can be used to make hydrogen-based fuels.

   Aerogel was used in the [3]NASA/JPL Stardust mission to collect
   cometary particles and interstellar dust.

   I wonder if it might have aerospace or automotive, too. Can you
   imagine an aircraft made of translucent, smoky, aerogel? Shades of
   Wonder Woman's invisible plane!

    The thinnest solid

   [4]Artist's rendering of graphene 

   [5]Graphene is a new material--a gauze of carbon atoms just one atom
   thick:

     Measuring less than 50 atoms wide and one atom thick, Andre Geim's
     graphene transistor may represent the best hope yet for delaying
     the expiration of Moore's Law. "Silicon will run out of steam in
     about 20 years," predicts Geim, a professor of condensed matter
     physics at England's University of Manchester. "We have to meet the
     challenge of keeping up with Moore's Law."

     A little over two years ago, Geim and fellow University of
     Manchester professor Kostya Novoselov discovered a new material
     class: a two-dimensional crystal, representing a single sheet of
     atoms. The material, graphene, is a gauze of carbon atoms
     resembling chicken wire and has become one of the hottest areas in
     physics research.

     "Until our discovery, this chicken wire was presumed not to exist
     in the real world," Geim says.

     The Manchester team reported the first graphene-based transistor at
     the same time as its materials discovery. The new transistor is a
     two-dimensional giant molecule thatâs still only as thick as a
     single atom. Other researchers have since reproduced the team's
     result, but these first-generation graphene transistors were very
     "leaky," meaning their electrical flow could not be switched off to
     zero.

     This limitation restricted the devices' potential use in
     high-density electronic circuits. But earlier this year, Geim and
     his team announced they had worked their way around the problem and
     can now produce graphene transistors that suit use in
     microprocessors and other chips.

References

   1. file://localhost/files/david-aerogelbrick.jpg
   2. http://en.wikipedia.org/wiki/Aerogel
   3. http://stardust.jpl.nasa.gov/photo/aerogel.html
   4. file://localhost/files/david-molecule-graphene.jpg
   5. http://elecdesign.com/Articles/index.cfm?ArticleID=16420&bypass=1