Researchers created an improved material that can harvest the heat (thermal energy) given off by machines.
The secret to the efficient material is a crystal structure that contains cerium atoms, a Vienna Institute of Technology press release reported.
"These trapped magnetic atoms are constantly rattling the bars of their cage, and this rattling seems to be responsible for the material's exceptionally favorable properties," the press release reported.
The crystals, called "clathrates," are affected by the behavior of the trapped atoms.
"These clathrates show remarkable thermal properties," Professor Silke Bühler-Paschen of Vienna University of Technology, said. "We came up with the idea to trap cerium atoms, because their magnetic properties promised particularly interesting kinds of interaction."
This is the first time researchers have accomplished the seemingly-impossible task of incorporating magnetic material into a crystalline structure. The team used an advanced crystal growing technique conducted in a mirror oven to create the material.
"The thermal motion of the electrons in the material depends on the temperature," Bühler-Paschen, said. "On the hot side, there is more thermal motion than on the cold side, so the electrons diffuse towards the colder region. Therefore, a voltage is created between the two sides of the thermoelectric material."
The "rattling" atoms were found to increase the thermopower of the clathrates by at least 50 percent. This allows the materials to spawn a much higher voltage.
"The reason for these remarkably good material properties seem to lie in a special kind of electron-electron correlation -- the so-called Kondo effect," Bühler-Paschen said.
The trapped electrons are "quantum mechanically linked" to the crystalline structure. The Kondo effect is usually considered to be at a very low temperature, but these correlations play a role even when the clathrates reach hundreds of degrees Celsius.
The rattling of the trapped cerium atoms becomes stronger as the temperature increases. This rattling stabilizes the Kondo effect at high temperatures. We are observing the world's hottest Kondo effect," he said.
