17: Planes and Planar Density

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17 Planes and Planar Density

• Andrew Kuntjoro
• 1/26/07

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Problem Statement 17
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Why is Identifying the Plane Important?

• Physical properties can change depending on the
  chosen plane
• Different planes may have different surface areas
• Can affect tests such as diffraction patterns

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Review of Planes

• Translate plane off of origin.
• Determine intercepts a, b, c
• Take reciprocals
• Reduce to integers

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Identifying the Plane

• 17 (a)

• Extend down to the x and y axes
• a 2, b 2, c 1
• Take reciprocal and simplify to integers
• (112) plane

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Planar Density

• Important in plastic deformation (slip)
• Defined as
• Chromium
• BCC structure ?
• Atomic radius .1249 nm

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Determining Planar Density

• 17(b)

• Extend to create a tessellating plane
• Creates a rhombus shape
• Major diagonal
• Minor diagonal
• 4 atoms on plane
• 3 in middle, 4 quarter atoms at corners
• Planar Density -
• PD 9.81 atoms/nm2