New material properties discovered by researchers at the University of Miami may impact ongoing research into thermoelectric materials, which are useful in power generation, energy detection and refrigeration and cooling.
Lead author Joshua Cohn, professor and chairman of the UM Department of Physics, and his colleagues report new properties of a metal known as lithium purple-bronze (LiPB) in the journal Physical Review Letters they say could help boost green technologies.
“If current efficiencies of thermoelectric materials were doubled, thermoelectric coolers might replace the conventional gas refrigerators in your home,” Cohn, who is the lead author of the study, said. “Converting waste heat into electric power, for example, using vehicle exhaust, is a near-term ‘green’ application of such materials.”
According to the researchers, the most useful thermoelectric materials produce a large voltage for a given temperature difference—a ratio known as thermopower. LiPB is unique, however, in that it exhibits different thermopowers when the temperature difference is applied parallel or perpendicular to the aligned conducting chains that make up the material.
In particular, the researchers discovered the material exhibited the most efficient transverse Peliter effect of any known single compound. The phenomenon describes the application of an electric current in a direction slightly misaligned with the chains that make up the material to evoke a heat flow perpendicular to the current.
“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.”
Of particular importance to this discovery, he added, is the possibility that other similar materials could be identified by studying LiPB’s structure.
“The present material might be useful as it is,” he says, “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.”