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Definition of atomic planes

  1. Aug 26, 2008 #1
    Atomic planes are defined as the reciprocal quantities 1/u' , 1/v' and 1/w' transformed to the smallest three integers (here the plane intersects the crystal lattice at the unit-cell axes u'a,v'b and w'c).

    My question is, why are reciprocal quantities used? This is something that has bugged me for a very long time... it seems pretty arbitrary to me.
  2. jcsd
  3. Aug 27, 2008 #2


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    It's not arbitrary.

    For any general plane described by the equation, [itex]ax+by+cz+d=0[/itex], verify that the intercepts are given by: -d/a, -d/b and -d/c.

    That's the origin of the Miller Indices - they describe the coefficients a,b,c in the equation of the plane (or the direction cosines of its normal).
  4. Aug 29, 2008 #3
    Thanks for the tip, it makes sense now, I just hate learning things without knowing the reason behind it.
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