Saturday, June 8, 2013

Cement Glass




 This is unexpected to say the least. Of course we may have a solution now in search of a problem. Yet it is very intriguing and suggestive.

This also informs us that any substance that is stable chemically can be melted and set up as a glass to allow a useful revisit regarding its properties.

Better yet it may be possible to so float extremely thin layers of such glasses, chemically alter them and perhaps even partially shape them in this way. All this is important for the ultimate manufacture of multi layered structures for the future aerospace industry.

All good.


Modern-day alchemists turn cement into metal

    By Sebastian Anthony
    May 28, 2013


It’s not quite lead into gold, but a team of international researchers have succeeded in turning cement into metal. This metallic form of cement, which is electrically conductive and has increased corrosion resistance, might find applications in protective coatings, thin films (think LCD monitors), and computer chips.

Cement, which usually consists of calcium oxide and other common minerals such as silicon dioxide and aluminium oxide, is of course an insulator. To turn cement into a metal, the researchers heat the powder to 2,000 Celsius (3642F) with a laser, turning the powder into liquid. A fantastic device called an aerodynamic levitator, which uses nozzles pumping out inert gas to levitate a material, is then used to levitate the molten cement. The levitator prevents the molten cement from touching the walls of the container, preventing unwanted crystal formation. Different gases are introduced into the chamber to modify the chemical bonds that formed as the liquid cement cools into a glass.



Electrons (the blue blobs) trapped inside calcium oxide cages

The result is a calcium oxide/aluminium oxide glass that is structured in such a way that free electrons are trapped inside cages made of calcium oxide. These trapped electrons allow for conductivity, much like the “sea” of electrons in a conventional metal. This phenomenon of trapping electrons inside a crystal’s structure is fairly new, and this work, carried out by Chris Benmore of the DoE’s Argonne National Laboratory and Shinji Kohara from the SPring-8 synchotron in Japan, along with a handful of European material scientists, is the first to clearly confirm, define, and image the electron trapping. Previously, this electron trapping had only been observed in ammonia — but now that the scientists know how to turn solid insulators into room-temperature semiconductors, some interesting innovations could emerge.

As you’ve probably surmised by now, this special cement isn’t a metal in the copper or iron sense of the word. Rather, the metallic cement is closer to a semiconductor, such as silicon (which, in case you were wondering, is a metalloid). In some ways, though, being a semiconductor is actually more useful. Already the scientists are speculating that semiconducting cement could be used as thin-film resistors in LCD displays. If the special cement can be mass produced, it’s easy to imagine it being used as a protective coating that also serves some kind of conductive purpose (in a connected smart home, perhaps?) Perhaps more importantly, though, it will be interesting to see if this new process can be used to turn other normally-insulating materials into semiconductors.

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