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Changing state from solid to liquid by application of electric current

  1. Nov 26, 2006 #1
    Hi

    Does there exist a material whose state it is possible to change from a solid to liquid by application of electric current? Obviously a large enough current will melt anything, but what I mean is is there some other mechanism, other than brute force heating that can cause a solid to "melt"?

    Regards
    roger5
     
  2. jcsd
  3. Nov 26, 2006 #2

    Danger

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    Welcome to PF, roger5. The only one that I know of is the other way around. There are (electrophoretic?) liquids that gel when subjected to a voltage. They're used in some shock absorbers, actuators, etc..
    I'm not sure if that's the right term for them, but I'll take a look around and try to find some.

    edit: Here ya go...
    http://bric.postech.ac.kr/trend/science/2003/03_10now/031006b.html
     
    Last edited: Nov 26, 2006
  4. Nov 27, 2006 #3
    Thanks
    I will look into electrophoretic materials. Looks like it might do the trick.
     
  5. Nov 27, 2006 #4
    I meant Electrorheological Fluids. Not sure how I got from electrophoretic to electrorheological but is that what you meant?
     
  6. Nov 27, 2006 #5

    Danger

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    Yeah... I just couldn't remember the name. :redface:
    It might also help to check 'Gizmag.com' or old SciAm magazines. There are articles about developing artificial muscles for robots. Some of that stuff might be applicable to your research as well. Come to think of it, I believe that there's also a thread about it around here somewhere (Mechanical Engineering, I think). Try a forum search.
     
  7. Nov 27, 2006 #6
    ok. Thanks.
     
  8. Nov 28, 2006 #7
    Perhaps a high frequency (~1018 Hz) alternating current out of phase with atomic bonds would cause them to loosen, i. e., change phase from solid to liquid.
     
  9. Dec 2, 2006 #8

    1018 Hz alternating current?
    That's the property of fairly energetic X-ray.I Never heard somebody call it an alternating current.
     
  10. Dec 2, 2006 #9
    How are those X-rays generated, if not in part by an alternation of charge?
     
  11. Dec 2, 2006 #10

    ZapperZ

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    There are no x-rays generated by "alternating current". X-rays in medical usage are created either using electron bombardment to cause a K-shell transition in an atom, or via bending magnets of electron beams.

    Zz.
     
  12. Dec 2, 2006 #11
    How would you produce ,control, and ,especially, set out of phase with atomic bonds such current Loren ?:smile:
     
  13. Dec 3, 2006 #12
    Take a hypothetical tunable X-ray laser illuminating a crystal (re the Bragg experiment) whose diffraction can be fed back (electronically) to the laser. At sufficient intensity and a particular tuned in-out phase difference (most likely 180o) the crystalline bonds would undergo sufficient stress to break, and liquefaction could be possible. Similarly (re the Davisson-Germer experiment) a current of electrons corresponding to an X-ray de Broglie wavelength may interfere with the crystal lattice.

    Remember that any conductor involved in such an experiment as you first suggested will itself be vulnerable to melting.
     
  14. Dec 3, 2006 #13

    ZapperZ

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    Eh?

    Can you please cite papers where these have been done?

    Zz.
     
  15. Dec 3, 2006 #14
    ZapperZ,

    tehno asked how I would perform such an experiment. Mine is indeed speculative. Perhaps someone else can provide a more appropriate procedure with citations.
     
  16. Dec 3, 2006 #15

    ZapperZ

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    I can tell you that it is speculative and unverified, even in principle. Besides, it is no longer relevant to the thread. Re-read the OP and notice that we're not talking about "melting". I could have easily brought up laser ablation in which one literally blows off material into a plasma. However, such a thing isn't relevant to the thread and isn't what is asked for.

    So you need to show me where, during a typical "Bragg Scattering" either using x-rays or electrons, that one can actually achieve such a thing that you're describing. After all, x-ray diffraction and electron diffractions are done a gazillion times a day at facilities all over the world. Sure there is at least ONE evidence to support what you're saying from that many experimental work.

    Zz.
     
  17. Dec 4, 2006 #16
    I was not able to find a reference to support my above idea - I agree that the assertion is somewhat off the subject.

    Has anyone mentioned liquid crystals yet? They appear solid under application of a potential.

    A magnetic field (generated by a current) usually manifests increased symmetry (phase change) in its environment while locally reducing entropy. How does the direct introduction of a current affect the entropy of a (solid) system?
     
  18. Dec 4, 2006 #17

    Danger

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    Loren, liquid crystals change their polarization in response to an electrical stimulus. They don't become any more solid than they are to start with.
    As for the mageto or electro rheological fluids, they work because they are more or less a colloidal solution of ferrous material in a liquid carrier.
     
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