A lot of energy is wasted when machines turn hot, unnecessarily heating up their environment. Some of this thermal energy could be harvested using thermoelectric materials; they create electric current when they are used to bridge hot and cold objects. At the Vienna University of Technology (TU Vienna), a new and considerably more efficient class of thermoelectric materials can now be produced.
Clathrates: Tiny cages enclosing single atoms are shown. Credit: TU Vienna
It is the material's very special crystal structure that does the trick, in connection with an astonishing new physical effect; in countless tiny cages within the crystal, cerium atoms are enclosed. These trapped magnetic atoms are constantly rattling the bars of their cage, and this rattling seems to be responsible for the material's exceptionally favourable properties.Cerium Cages from the Mirror Oven
Experiments show that the cerium atoms increase the material's thermopower by 50%, so a much higher voltage can be obtained. Furthermore, the thermal conductivity of clathrates is very low. This is also important, because otherwise the temperatures on either side would equilibrate, and no voltage would remain.The World's Hottest Kondo Effect
"The rattling of the trapped cerium atoms becomes stronger as the temperature increases", says Bühler-Paschen. "This rattling stabilizes the Kondo effect at high temperatures. We are observing the world's hottest Kondo effect."
Further Information:Prof. Silke Bühler-Paschen
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