New Material Traps Atoms in Individual Cages to Create Energy More Efficiently

Researchers have developed a new material that, according to its creators, can be used to create electricity from heat more efficiently. 

When machines turn hot, they waste energy as they cause the temperatures in their environment to rise. In order to harvest this thermal energy, researchers developed thermoelectric materials, which create an electric current when linked hot and cold objects.

"The thermal motion of the electrons in the material depends on the temperature," Silke Buhler-Paschen, a scientist at Vienna University of Technology (TU Vienna), said in a statement. "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."

Buhler-Paschen and her colleague Andrey Prokofiev, also from TU Vienna, have created a new class of thermoelectric material produced that, according to its creators, is far more efficient than its predecessors.

The trick lies in a unique crystal structure and the capturing of individual atoms in tiny cages within it.

The word "clathrates" refers to crystals in which atoms are enclosed. According to Huhler-Pashcen, those used in the new design "show remarkable thermal properties."

Influencing the material's behavior is the interaction between the trapped atoms and their cage. The idea to trap cerium atoms, the researcher explains, came from their magnetic properties which, she said, "promised particularly interesting kinds of interaction."

Key to the project's success was a sophisticated technique of crystal growth carried out in a mirror oven that ultimately allowed the researchers to succeed in developing clathrates from barium, silicon and gold -- each containing a single cerium atom.

Based on their experiments, the researchers determined that the cerium atoms increased the material's thermopower by 50 percent, allowing for a much higher voltage.

Going forward, the scientists hope to achieve the same effect with other kinds of clathrates, substituting the expensive materials -- such as gold -- with cheaper alternatives in order to develop a commercially attractive model.