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Ultra-pure Glass Made with Levitation
lc_overlord writes "Space.com has a story on a new type of glass. 'Using static electricity fields to levitate the material, scientists were able to construct a pure glass, free of any contamination typically associated with containers.' The glass is made of rare earth aluminum oxide and small amounts of silicon dioxide."
Well, if you don't mind it being Aluminium Oxide, which is a ceramic, it's been around at least two years, Article, though I seem to recall seeing a varient of this before 2000 in a Popular Science magazine.
You never know...
Sapphire has been around considerably longer than two years.
Perhaps you were refering to nano-scale polycrystalline alumina, which has still be around longer than two years.
As mentioned in the article, these ultra-pure glasses are needed for industrial lasers. Impurities or contamination in a laser glass can absorb the laser energy, be ioned, and explode within the laser glass. Tradionally, large scale glass melting is performed in ceramic refractory lined tanks. The problem is that glass melts are highly corrosive and a significant amount (any amount is significant when dealing with high powered lasers) of contamination will occur.
For the laser glass blanks used for the National Ignition Facility NIF Website, U.S. taxpayers supplied platinum lined tanks to prevent refractory contamination in the glass blanks. However, even platinum is soluble in the phosphate based glasses used for these blanks. Platinum colloids would result in catastrophic failure of the glass once the lasers where powered up So, a great deal of research has been performed by the glass science community (thank you DOE) to learn how to alter the glass chemistry via composition or processing parameters in order to incorporate these tiny levels of platinum into the glass structure and render it harmless in the finished product.
If significant quantities of these types of glasses could be made using containerless levitation, the expense of platinum lined glass tanks and challenges of neutralizing what little platinum contaminates the glasses would be eliminated.
I'd say, they mean, aluminium oxide glass (amorphous AlO) doped with a tiny fraction rare earth salts. Many solid substance lasers use rare earthes today, YAG (Yttrium Aluminium Granat [sp?]) for example.