19-May-2014 - University of Miami

New insight into thermoelectric materials may boost green technologies

Thermoelectric materials can turn a temperature difference into an electric voltage. Among their uses in a variety of specialized applications: generating power on space probes and cooling seats in fancy cars.

University of Miami (UM) physicist Joshua Cohn and his collaborators report new surprising properties of a metal named lithium purple-bronze (LiPB) that may impact the search for materials useful in power generation, refrigeration, or energy detection. The findings are published in the journal Physical Review Letters.

"If current efficiencies of thermoelectric materials were doubled, thermoelectric coolers might replace the conventional gas refrigerators in your home," said Cohn, professor and chairman of the UM Department of Physics in the College of Arts and Sciences and lead author of the study. "Converting waste heat into electric power, for example, using vehicle exhaust, is a near-term 'green' application of such materials."

Useful thermoelectric materials produce a large voltage for a given temperature difference, with the ratio known as "thermopower." LiPB is comprised of aligned conducting chains. The researchers found that this material has very different thermopowers when the temperature difference is applied parallel or perpendicular to the conducting chains. When an electric current was applied in a direction slightly misaligned with the chains, heat flowed perpendicular to the current, a phenomenon known as the "transverse Peltier effect." The efficiency of this effect in LiPB was among the largest known for a single compound. "That such a large directional difference in thermopower exists in a single compound is exceedingly rare and makes applications possible," Cohn said. "This is significant because transverse Peltier devices typically employ a sandwich of different compounds that is more complicated and costly to fabricate."

As their motivation for the work, Cohn noted that metals with a similar electronic structure often exhibit interesting physics and the thermoelectric properties of LiPB had never been studied in detail. "The present material," he said, "might be useful as it is, but the larger implication of our work is that the ingredients underlying its special properties may serve as a guide to finding or engineering new and improved materials."

Facts, background information, dossiers
  • University of Miami
  • lithium
  • transverse Peltier effect
  • thermoelectricity
More about University of Miami
  • News

    Chemists create new artificial enzyme

    Enzymes are nature's powerhouses. Found in the cells of all animals, plants, and every other living organism, they accelerate the chemical reactions that trigger thousands of biological functions--from forming neurons to digesting food. They perform their jobs so selectively and so quickly- ... more

    New insight into thermoelectric materials may boost green technologies

    Thermoelectric materials can turn a temperature difference into an electric voltage. Among their uses in a variety of specialized applications: generating power on space probes and cooling seats in fancy cars. University of Miami (UM) physicist Joshua Cohn and his collaborators report new s ... more

    Magnetism and an electric field

    There is a big effort in industry to produce electrical devices with more and faster memory and logic. Magnetic memory elements, such as in a hard drive, and in the future in what is called MRAM (magnetic random access memory), use electrical currents to encode information. However, the hea ... more