1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Miller index

  1. Nov 9, 2009 #1
    for the following SC cube, find the miller indexes for the planes:
    FAN
    KFA
    HAN
    http://lh6.ggpht.com/_H4Iz7SmBrbk/SvhiU8OeicI/AAAAAAAAB8M/o8QPR2ht2gA/Capture.JPG [Broken]

    what i leared to do was find the points that the plane intercepts the x,y,z axis, i chose axes such that x+ is pointing right and y+ upwards, then i divide to get a ratio, and then ()^-1
    i chose the length of a side of the cube to be "a"

    FAN -> a,a,a -> 1,1,1 -> 1 1 1
    KFA-> a,inf,a -> 1,inf,1 -> 1 0 1

    now for the 3rd one i have found the intercept with the z axis which came out as 1.5a
    HAN-> a,a,1.5a -> 1,1,1.5 -> 1 1 2/3

    my question is if i am meant to do it like that or if i am meant to divide by 1.5a instead of just a
    HAN-> a,a,1.5a -> 2/3,2/3,1 -> 1.5 1.5 1

    up until this question i have only had whole numbers in the muiller index, so i thought another option could be
    HAN-> a,a,1.5a -> 2,2,3 -> 0.5 0.5 1/3

    but then i have on;y fractions,

    could someone please clear this up for me, which way (if any )) is the correct way?
     
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Nov 9, 2009 #2

    Mapes

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    It's customary to use all whole numbers.
     
  4. Nov 10, 2009 #3
    so then
    3 3 2 ????
     
  5. Nov 10, 2009 #4

    Mapes

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Looks good to me.
     
  6. Nov 10, 2009 #5
    now my second question is does it matter what i call xyz?? since they arent defined in the question, i chose xyz as i said but a friend of mine chose different and we obviosly got different answers. for example he would get 2 3 3 for the above index.
    is there any standard axes system or can i choose any right handed system?
     
  7. Nov 10, 2009 #6

    Mapes

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Your friend's answer is equivalent since, as you suggest, Nature doesn't have a preferred coordinate system.
     
  8. Nov 13, 2009 #7
    Mapes, would it not be 223 since it intercepts the z axis at1.5 times the point it intercepts the x,y axes. or is this correct since i apply ()^-1 to the whole index?
     
  9. Nov 13, 2009 #8

    Mapes

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    233 looks right to me. If you look at the surface normal, there's one direction whose resolved component is smaller and two whose components are equal and larger. Plus, I agree with your original calculations.
     
  10. Nov 13, 2009 #9
    can you explain what you said about the normals a bit more, how do i see that there is one which ils smaller?
     
  11. Nov 13, 2009 #10

    Mapes

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Well, the plane contacts point H instead of point F, so it's not angled towards the z axis as much as it would be if it were a 111 plane. But this is kind of the "casual" way of estimating the indices. The reciprocal approach is the rigorous way, which you showed in your first post.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Miller index
Loading...