Scientists Create Material More Insulating than the Vacuum
clipped from www.physorg.com
clipped from www.physorg.com(PhysOrg.com) -- With its complete lack of atoms, a vacuum is often considered to be the best known insulator. For this reason, vacuums are regularly used to reduce heat transfer, such as in the lining of a thermos to keep beverages hot or cold. However, in a recent study scientists have found a material even less able to conduct heat: a stack of photonic crystals layered within a vacuum can create a material with a thermal conductance just half that of empty space alone.
clipped from focus.aps.orgPhotonic Thermos
Not the best. A complete theoretical analysis shows why a photonic crystal should insulate better than the vacuum jacket of a thermos. The photonic crystal would insulate by blocking much of the infrared radiation a warm object emits--radiation that can cool the object even when it's surrounded by vacuum.
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Scientists create material more insulating than a vacuum; smart windows on horizon
A new material made of photonic crystals may be more insulating than a vacuum that completely lacks atoms.
Led by Shanhui Fan, the researchers set out to create a material that addressed that pesky third source of heat transfer: infrared radiation. Photonic crystals, which consist of bands of nanostructures that affect how light travels through them, were the solution.
So what’s the importance of a better vacuum? As I mentioned above, smarter windows on cars, homes and offices is a start. With photonic crystals, smart windows could capture the sun’s heat for use as an energy source while allowing visible light to pass through uninterrupted.
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Sources:
- Scientists Create Material More Insulating than the Vacuum
- vacuumflask.jpg (JPEG Image, 200x346 pixels)
- Photonic Thermos | Physical Review Focus
- Scientists create material more insulating than a vacuum; smart windows on horizon - SmartPlanet
