Capturing heat that would otherwise have been lost – ScienceDaily

The discovery, published last week in the newspaper Progress of science, could generate more efficient energy generation from heat, including car exhaust gases, interplanetary space probes and industrial processes.

"With this discovery, we should be able to produce more electrical energy with heat than today," said Joseph Heremans, co-author of the study, professor in mechanical and aerospace engineering and distinguished researcher in nanotechnology from Ohio to Ohio State University. "It's something no one thought possible up to now."

The discovery is based on tiny particles called paramagnons – bits that are not quite magnets, but carry a magnetic flux. This is important because magnets, when heated, lose their magnetic force and become what is called paramagnetic. A flow of magnetism – what scientists call "spins" – creates a type of energy called magnon drag thermoelectricity, which, until this discovery, could not be used to collect the energy. 39, energy at room temperature.

"Conventional wisdom once was that if you have a paramagnet and you heat it, nothing happens," said Heremans. "And we found that this is not true.What we discovered is a new way of designing thermoelectric semiconductors – materials that convert heat into electricity." The conventional thermoelectrics that we have known for twenty or so years are too inefficient and give us too little energy, so they are not really used.This changes this understanding. "

Magnets play a crucial role in the collection of heat energy: when one side of a magnet is heated, the other, the cold side, becomes more magnetic, producing a rotation that pushes the electrons into the magnet and creates electricity.

The paradox, however, is that when magnets are heated, they lose most of their magnetic properties, which turns them into paramagnets – "magnets almost, but not quite," called them Heremans. This means that, until this discovery, no one thinks of using paramagnetics to harvest heat because scientists thought that paramagnetics were not able to collect energy.

The research team, however, found that paramagnons only grow electrons for one billionth of a millionth of a second – enough time for paramagnetics to become viable energy recuperators.

The research team – an international group of scientists from the Ohio State, North Carolina State University and the Chinese Academy of Sciences (all authors equal in this review article) – began to test paramagnons to see if they could, under the right circumstances, produce the necessary spin.

Heremans explained that what they discovered, is that paramagnons actually produce the type of spin that drives electrons.

And that, he said, could help to collect energy.

Yuanhua Zheng, a graduate student from the state of Ohio, is also an author of this work. The research was conducted in partnership with other researchers at the US Department of Energy's Oak Ridge National Laboratory and was supported by the National Science Foundation, the Air Force Scientific Research Bureau and the US Department of Energy. energy.

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Material provided by State University of Ohio. Original written by Laura Arenschield. Note: Content can be changed for style and length.