Converting cement to metal: innovation or modern-day alchemy?
Forget the lustrous shine
of the aluminum iPhone casing or the HTC’s magnesium alloy plating – there is a
new metal in town and it presents itself as the product of
modern alchemy in a slick and futuristic way.
At the end of May, 2013, Scientists discovered and successfully used a formula to turn cement into liquid metal which can then be molded and cooled. It presents a novel use for cement as a semi-conductor and can be compounded to create computer chips, protective coatings and thin films (think LCD monitors).
Chris Benmore, a physicist from the U.S. Department of Energy’s Argonne National Laboratory and his team of Japanese, Finnish and German scientists worked in unison to create a metallic-glass material from what was once liquid cement. The new material showed better resistance to corrosion than ordinary metal (i.e. it does not rust), higher insulation of magnetic energy, malleability, and electrical conductivity versus the more traditional metals of our time.
The calcium and aluminum oxides in powdered cement are heated to 2,000 Celsius (3642F) with a laser, turning the powder into liquid. A device called an aerodynamic levitator uses a nozzle pumping out inert gas to levitate the liquid cement, preventing it from crystalizing into the shape of the chamber which contains it. Researchers then introduce different gases to modify the chemical bonds of the oxides as they cool into a glass.
The result is a large-scale trapping of mobile electrons in the cage-like structures of calcium oxide (on a molecular level), allowing for a huge increase in the material’s electrical conductivity (see illustration here). The mechanism by which this conversion is possible is known as electron trapping 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 successful use of the electron trapping method.
The results were reported on May 27 in the journal “Proceeding of the National Academy of Sciences”. See it here.
On a more interesting note, we are now able convert other normally-insulating materials into semiconductors. "Now that we know the conditions needed to create trapped electrons in materials," Benmore said, "we can develop and test other materials to find out if we can make them conduct electricity in this way."