4/ (The "Carnot limit" is the maximum possible efficiency of any thermodynamic cycle.)
Conversation
5/ This finding was potentially a big deal technologically (we filed for a patent), and a number of groups started looking for experimental confirmation.
Within a year, there were two experiments that seemed to confirm the theory:
nature.com/articles/s4146
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6/ But one of these experiments was a little _too_ good. The thermopower (the ratio of temperature difference applied to voltage difference created) rose by more than two orders of magnitude in a magnetic field. Even in conditions where our theory was not obviously applicable.
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7/ The published explanation was that this measurement was a confirmation of our theory. But I wasn't sure, so I set my graduate student Xiaozhou Feng to think critically about whether perhaps the theory I had written down was the wrong explanation.
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8/ What a good decision that was! We ended up showing that there was a different mechanism at work in this material, which gave an even more dramatic field-enhancement of thermopower.
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9/ Even better, this mechanism turned out to be generic for all "compensated" systems, which are materials that carry electric current simultaneously through positive and negative charges. This opens the door to a much wider range of materials as efficient thermoelectrics.
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10/ The paper is now an "Editors' suggestion" and is featured on the website of the journal Physical Review Materials.
journals.aps.org/prmaterials/
(The free version is here: arxiv.org/abs/2010.07933)
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11/11 Many congratulations to Xiaozhou Feng for an excellent piece of work, and for his first published paper!
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Replying to
I was just reading about the MMRTG used on Mars Rovers and they seem to have an awful power efficiency of ~5% (the plutonium generates ~2000W of heat, but the rovers get only 110W of electricity out of it). Do you think there's potential for higher efficiency using your results?
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I think there's definitely potential. It's still pretty far from a specific proposal for a working device, and at this stage I still wouldn't bet even odds on this working out. But there's a core idea that I like, and I hope will go somewhere.
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space is a particularly attractive application since above a particular combo of size and distance, solar doesn't work and MMRTGs are pretty much the only game in town for power
Replying to
yeah space applications are the one situation where thermoelectrics are really competitive (helps that they have no moving parts!)
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