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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 Black69ta on 10/8/2008 5:09:09 PM , Rating: 2
Weight: Photons are much lighter than electrons, Electron don't travel in a straight line but more like water particle in an ocean wave. Photons in a fiber optic cable are generally produced from a laser which makes them uniform and in phase. thus the don't collide as much and when they do the energy involved is much less.

RE: Pinky calling for the Brain.
By Chemical Chris on 10/8/2008 5:27:35 PM , Rating: 3
Photons don't weigh anything, actually.
And are they particles, or waves...both you say, well....alrighty then, i guess
I think the current idea is something along the lines of they are too small (or are just unable) to interact with the Higgs field that permeates everything.
Of course, we should know if thats a credible theory next year.... gotta hate it when there's ~9999 good soders, and 1 bad soder job brings down the whole $9 billion LHC :(
But I digress, photons, very small, have no mass, but have energy (which violates e=mc2, but so it goes)

RE: Pinky calling for the Brain.
By Integral9 on 10/9/2008 8:52:14 AM , Rating: 2
I'm pretty sure photons have been proven to have mass. An incredibly small amount of it, but some. The solar sail theory is based on it and I think it was proven correct. Anyone?

RE: Pinky calling for the Brain.
By theapparition on 10/9/2008 10:36:25 AM , Rating: 2
Photons have no mass. None.

Solar Sail theory is based that even though photons don't have mass, they do carry momentum.

RE: Pinky calling for the Brain.
By geddarkstorm on 10/9/2008 1:49:35 PM , Rating: 2
Which means photons must have an inertial mass: p=mv where p is momentum, m is mass and v is velocity. Arthur Holly Compton showed this when studying x-ray diffraction, where the x-ray quanta have momentum proportional to their frequency (the higher the frequency, the more the wave "moves" over the same distance, which would give it an increased velocity for the particle, or photon, aspect).

So, as someone else pointed out, light has no resting mass (if it isn't moving it doesn't exist), but has relativistic (inertial) mass.

RE: Pinky calling for the Brain.
By Adonlude on 10/13/2008 5:27:15 PM , Rating: 2
NOPE. The simple answer is that after several thousand years we have not yet managed to assemble a system of thought and calcualtion that encompases life, the universe, and everything.

I predict we will one day build a computer that operates not in base 2 but in base 42 and through simulation we will finally figure it out. The symbols utilized in this base 42 computer will be 0-9 (look at your hands) as well as the 32 symbols of the ancient Ugaritic Alphabet. These 42 symbols form the original foundation of human communication.

RE: Pinky calling for the Brain.
By theapparition on 10/9/2008 10:35:16 AM , Rating: 2
Photons don't violate E-mc². The equation only serves to relate mass and energy.

RE: Pinky calling for the Brain.
By Chemical Chris on 10/9/2008 11:16:16 AM , Rating: 2
energy = mass * speed of light^2
so, if it has energy, but no mass, you get:
real number = 0 (ie, 5=0)
clearly, a real number cannot equal 0. So, yes, it sure appears violated to me. If it has mass, it must have energy, and if it has energy, it must have mass. Please correct me if Im wrong (with some evidence, not just 'because i said so', if im wrong, then i get to learn something :)
I can see how it "isnt violated", in that a photon with energy can be destroyed to create mass, or that mass can be destroyed to create a photon, which is true. Its also a part of how nuclear weapons work (a small amount of mass is converted to energy; while no large subatomic particles are destroyed, some of the 'gluons' in the nucleus are destroyed. That is, the mass of subatomic particles and atoms generated from fission/fusion have less mass than their original atom. All atoms 'lose' a small fraction of mass relative to their component parts, called the 'nuclear packing fraction", ie, even though Oxygen has 8 protons and neutrons and should weigh 16, its actually (IIRC) 15.994 (real mass for O-16, not average of all O isotopes)

RE: Pinky calling for the Brain.
By amanojaku on 10/9/2008 11:49:04 AM , Rating: 2
You might want to check your facts.

In physics, mass–energy equivalence is the concept that for particles slower than light any mass has an associated energy and vice versa. In special relativity this relationship is expressed using the mass–energy equivalence formula E=mc^2

A photon has a rest mass of 0 and therefore does not violate mass-energy equivalence. Its relativistic mass is equal to its energy, E/c^2.

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