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A new discovery made in thermoelectrical crystal compounds helps explain heat conduction at the molecular scale.

Though thermoelectric materials are quite common, they are not yet widely used as one might expect. The reason is largely that until very recently, these materials have been either very inefficient or very expensive. However, several groups of researchers have been working to solve the mysteries of these exotic compounds and bring them to the world en masse.

DailyTech has previously reported on a few endeavors with thermoelectrics. Mildred S. Dresselhaus's ongoing work at the Massachusetts Institute of Technology looks to create more efficient materials by manufacturing tiny particles or wires into them to disrupt the flow of heat. This would make materials that are already great electrical conductors much more thermally inert, allowing for greater heat-to-electricity or electricity-to-heat/cold conversion potential.

Another group at the University of California at Berkley, led by Professor Peidong Yang is looking into new materials. Silicon itself is not a great thermoelectric material – until venturing into nanoscale. Silicon nanowires have been shown to be one hundred times more efficient at the energy conversion than bulk silicon.

Publishing its findings in the most recent issue of Nature Materials, a group of scientists from the University of Århus, Risø-DTU and the University of Copenhagen has unlocked another secret of certain thermoelectric compounds which may help develop more efficient materials. Their work involves clathrate compounds, which are compounds composed of a “cage” of one type of molecule that surrounds a second type.

Initially it was believed that the movement of the trapped molecule was solely responsible for the way the compound conducted heat. After using neutron scattering to study the movement of the atoms inside the molecules, they realized it was the movements of the atoms in the cage that brought about the advantageous property.

Kim Lefmann, an associate professor of the Nano-Science Center, Niels Bohr Instituate at the University of Copenhagen explains, “Our data shows that, it is rather the atoms' shared pattern of movement that determines the properties of these thermoelectric materials. A discovery that will be significant for the design of new materials that utilize energy even better.”

Understanding the mechanism behind this thermal insulation will help scientists design better thermoelectric materials. These types of materials are finally being put to use in some of the places you might expect, such as vehicle auxiliary power generation from waste heat. The same waste heat could theoretically be used to power interior cooling systems via heat to energy to heat (and cooling) transference.

Thermoelectric materials have a tremendous amount of potential for use in everything from vehicles to homes and businesses to electronics. Better understanding of how these materials work will spawn more efficient materials and perhaps one day these things will be powered, cooled and heated by super thermoelectric devices.



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RE: Pinky calling for the Brain.
By Xajel on 10/9/2008 7:45:36 AM , Rating: 2
Electrons are :
- charged, they will have some resistance with other electrons in what ever they go through, this resistance will force the electron to not walk in a direct line, but rather some wavey line do to alot of attoms in the way.
- big and heavy, they will hit some attoms in thier way, of course hitting doesn't mean touching as this will need impressive amount of energy for that electron as the atom is self is covered with a cloud of electrons over the core.

Photons :
- non charged, photons doesn't have a charge like electrons, so they just walk fast in that matter.
- small and mass-less, photons are much much more smaller than even the electron it self, so they wont hit the electron cloud but they will penetrate the atom it self, and duo to the fact the atom has more than 95% of it's size just an empty space, photons can easly go throught it...
- it's interaction with materials in the fiberoptics, to a photon, fiberoptics are transparent, so they're designed to let as much as photons as possible, not 100%, but more closely to 95% - 99% depending on the quality, so the natural of fiber optics is similar to some near-vacume to electrons, of electrons are traveling trought a vacume, they wont hit any thing, so it will be something like transparent to them, ofcourse having a 100% vacume is too diffecult and hard as you have to make sure there's not even any atom in that space, even in the very deepest space they said it has 1 atom per cubic cm and that atom is H2 or He2 as they're the most common attoms in the known universe...


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