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Converting optical energy to electric energy is a huge business based on the photovoltaic effect. Is there an analogous effect for phonons? Are ther devices which convert phonon energy to electric energy

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up vote 6 down vote accepted

Yes. The Seebeck effect, for example, is the direct conversion of thermal gradient to electric voltage. It is used in the small scale in thermocouples to measure temperatures electronically, or in the larger scales in thermoelectric generators for power generation.

In fact, many of the long-range space probes launched by NASA get power this way. Radioactive material generates heat on decay, which gets converted to electricity, which then allows probes like Voyager 2 to have power faraway from the sun where solar power is not available.

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I am seeking an effect which does not require temperature gradient. Can a device be built which captures "flying" phonons and convert them to electric energy without the need for a colder surface? I am aware that such an idea may violate the 2nd law of thermodynamics, but I wish to know from a technological perspective why this is (not) feasible. –  Tarek Jul 12 '12 at 13:12
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@Tarek: So you seek something that you already know doesn't exist!? –  Hans-Peter E. Kristiansen Jul 12 '12 at 15:17
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How about the Piezo-electric effect?

if I'm not mistaken, pressure on the crystal is in essence equal to long-wavelength phonons.

If that's not what you're after, perhaps read this, or else this paper (both the result of a 5 minute Google scholar session).

They're don't seem to contain exactly what you're after (haven't read them thoroughly though), but are related nonetheless. At least they are a hint that a workable device to convert short-wavelength phonons to electrical energy is currently only available on the nano-scale.

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