Wednesday, August 11, 2004

It's so hot in here -- close the window

Article: Smart glass blocks infrared when heat is on� (22:00 09 August 04 - - Will Knight - Journal reference: Journal of Materials Chemistry DOI: 10.1039/b403576n)

Glass that blocks out heat but not light when a room starts getting excessively warm has been developed by UK scientists.

At most room temperatures the glass lets both visible and infrared light pass through. But above 29°C, a substance coating the glass undergoes a chemical change causing it to block infrared light. This will prevent room from overheating in bright sunshine or if temperatures outside start to soar. ...

The glass is coated the chemical vanadium dioxide. This material transmits both visible and infrared wavelengths of light, and normally undergoes a change at about 70°C.

Above this transition temperature, the electrons in the material alter their arrangement. This turns it from a semiconductor into a metal, and makes it block infrared light. Parkin and Manning lowered the transition temperature to 29°C by doping the material with the metal tungsten.

However, a number of issues still need to be overcome. Firstly, the substance is not permanently fixed to the glass. Also, the coating itself currently has a strong yellow tint.

But Manning believes it should be possible to overcome these issues. "You could add another substance, like titanium dioxide, to fix it to the glass," he told New Scientist. "And you could use a dye that would cancel out the yellow."

I suggest a lotion form of this stuff: a sunscreen that keeps us cool while still letting us catch a tan. Then again, it's probably safer to have the natural alarm system of hot skin if we're overcooking ourselves while worshipping Apollo and Ra and Ego.

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