Saturday, March 24, 2012

>Liquid-like materials may pave way for new thermoelectric devices<

In the continual quest for better thermoelectric materials -- which convert heat into electricity and vice versa -- researchers have identified a liquid-like compound whose properties give it the potential to be even more efficient than traditional thermoelectrics. Thermoelectric materials have been used to power spacecraft from Apollo to the Curiosity rover now headed for Mars. Recently, however, scientists and engineershave been turning to these materials to usewasted heat -- released from automobiles or industrial machinery, for instance -- as an efficient energy source. They have also proposed using these materials to create more efficient heating systems in electric cars or even as new ways to exploit solar power.
In identifying this new type of thermoelectric material, the researchers studied a material made from copper and selenium. Although it is physically a solid, it exhibits liquid-like behaviors due to the way its copper atoms flow through the selenium's crystal lattice.
"It's like a wet sponge," explains Jeff Snyder, a faculty associate in applied physics and materials science in the Division of Engineering and Applied Science at the California Institute of Technology (Caltech) and a member of the research team. "If you have a sponge with very fine pores in it, it looks and acts like a solid. But inside, the water molecules are diffusing just as fast as they would if they were a regular liquid. That's how I imagine this material works. It has a solid framework of selenium atoms, but the copper atoms are diffusing around as fast as they would in a liquid."
The research, led by scientists from the Chinese Academy of Science's Shanghai Institute of Ceramics in collaboration with researchers from Brookhaven National Laboratory and the University of Michigan, as well as from Caltech, is described in a paper recently published in the journal

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