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Ferrite Silcon core pros? & cons? (FeSi)

  1. Jan 21, 2007 #1
    Ferrite silcon (FeSi) core pros? & cons?

    I'm hoping for some input here to brainstorm. My unlearned theory is that a plyable substraight, in this case a cylinder, will allow the magnetic domains to come off of its' alignment when influenced to do so by an external force/field. The external input can come from a permanent magnet swipe, a magnetic strip, induced field from primary coils, impulses from audio sources etc....

    I guess I'll pose the first question.

    When magnetic domains are lined up in a NIB rare earth magnet or in a ceramic magnet... Are these domains lined up perfectly? If these lines of domains are only next to perfect in alignment, will this affect the over all strenght? And, even futher out, would it "turn off " meaning that the field would disappear altogether?
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  3. Jan 21, 2007 #2


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  4. Jan 21, 2007 #3
    Perhaps I wasn't concise in one of the FeSi-core property descriptions. This core is allowed to solidify, over time as silicone does, under the influence of an external magnetic field which will then lock the magnetic moments parrallel to each other. Correct me if I'm misinterpreting, but Long Range Ordering is to say that the electrons' spin line up in one direction reative to each other, making a long parallel chains, as it were. The magnetic domain is the erea in-between the electrons.

    So wouldn't the solidified and yet plyable silicone allow the electron spins/magnetic moments to be changed/tipped ever so slightly when an external field is applied? The Long Range Ording is also effected causing a long-range - shorter-range fluxuation.
  5. Jan 22, 2007 #4


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    Domains are NOT the area in-between the electrons. A domain is a part of the material where all the magnetic moments are aligned parallel to each other. When the magnetic material is subjected to an increasing external field, two things happen:

    i) Domain walls migrate in a manner that more aligned domains grow at the cost of less aligned domains, and

    ii) The magnetization of each of the domains rotates towards the applied field.

    Finally, at some saturating field, your entire magnet has just a single domain that is parallel to the direction of the applied field.
  6. Jan 22, 2007 #5
    Obviously I need you guys to be patient with me, Thanks Marcusl and Gokul43201.

    Allright. So if only two things happen after a ferrite inpregnated, solidified, silicon core is being induced by an external field. Is, more domains grow untill there is only one single domain, which I understand to mean the magnetic field will become some-what stronger and at its' strongest point when it becomes a single domain, the saturation point. But when you say the "magnetization of each of the domains rotates to the applied field". The now single domain only becomes a single domain when an external field is being induced, correct?. If so, prior to the induced field, it is more than one single domain, which renders the FeSi-core to be "not as strong?" or "not at all?" Remember that we are dealing with a plyable medium, silicon. The ferrite will move in and out of optimal domain induced positions, the optimal domain being, one single domain.
    Can I then safely summize that the FeSi-core can be turned 'On' from an 'Off' position by simply swiping, inducing it with an array of rare-earth magnets?
    Hey, Marcusl, Gokul43201 if this just sounds idiotic, tell me OK?
    Last edited: Jan 22, 2007
  7. Jan 22, 2007 #6


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    I imagine your material has ferrite particles imbedded in a silicone resin. If so, the pliability of the substrate will have little effect on the magnetic properties and the questions you are asking are the same as for all ferromagnetic materials. The key is to understand the B-H hysteresis curve. If you reduce the applied H field to zero the ferrite will retain a residual magnetization, which is how a magnet works. To truly demagnetize the material you need to run a "degauss cycle" around the hysteresis loop while H is gradually reduced.

    I suggest you follow the link to Hysteresis in the Hyperphysics article above as a start. There is plenty of other material on magnetism on the web as well.
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