Miller Index Problem - Is it (102) or (112)?

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Discussion Overview

The discussion revolves around determining the correct Miller index for a tilted plane, specifically whether it is (102) or (112). Participants explore the methodology for calculating Miller indices and the implications of intercepts on the axes.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions the Miller index for a tilted plane, suggesting uncertainty about whether it is (102) or (112).
  • Another participant asserts that every plane has a Miller index and describes the method for finding it in a cubic system, including the treatment of negative intercepts.
  • A participant challenges the assertion regarding the y-intercept, asking for clarification on why it is considered -1 when the plane does not seem to intersect the y-axis.
  • In response, another participant explains that the plane extends to infinity and intersects the y-axis at -1, suggesting to apply the same reasoning to other axes.
  • A participant seeks confirmation on whether extending the vector to intersect the y-axis implies the Miller index should be (1-12).
  • One participant confirms that the plane can be represented as (1\bar 1 2) and belongs to the family of \{112\} planes.
  • Another participant questions if (1,-1,2) represents the same plane, prompting a clarification that they are indeed the same plane.

Areas of Agreement / Disagreement

Participants express differing views on the correct Miller index, with some supporting (1\bar 1 2) while others suggest (102) or (112). The discussion remains unresolved regarding the definitive identification of the Miller index.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about the intercepts and the interpretation of the plane's geometry, which may affect the determination of the Miller index.

Carolyn
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Can somebody tell me what is the miller index for the tilted plane?

Is it (102) or (112)?

Nothing seems to fit...

I wonder if we can even describe it with miller index?

Please download the picture here in pdf format:

http://www.megaupload.com/?d=F8J344BH

Thanks!
 
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or see the attached file if you can...
 

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Every plane has a Miller index. A common way to find the Miller index for a plane in a cubic system is to take the reciprocal of the axis intercepts and normalize the result so it contains only integers. Negative intercepts are treated by putting a bar over the number. For example, the y-intercept in your figure is at -1.
 
thanks for the reply. But could you explain why is the y intercept for the triangular plane -1? it does not seem to intersect with the y axis?
 
The plane continues on to infinity; if you follow the line in the y-z plane, you'll see that it (and therefore the plane) intersects the y-axis at -1. Use the same approach for the other axes.
 
um..so are you saying that I can extend the vector so it eventually intersects with the y-axis?

so the miller index should be (1-12)?
 
Yes; a [itex](1\bar 1 2)[/itex] plane (a member of the family of [itex]\{112\}[/itex] planes), with surface normal vector [itex][1\bar 1 2][/itex] (a member of the family of [itex]\langle 112\rangle[/itex] directions).
 
But, for example, this picture is also (1,-1,2). so are they a family?
 

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More than another member of a family; that's the same plane.
 
  • #10
ok. I think I am getting it, thanks a lot.
 

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