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Objectives

jacinda
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Objectives

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    2. Lattice Planes and Miller Indices Imagine representing a crystal structure on a grid (lattice) which is a 3D array of points (lattice points). Can imagine dividing the grid into sets of “planes” in different orientations

    3. All planes in a set are identical The planes are “imaginary” The perpendicular distance between pairs of adjacent planes is the d-spacing Need to label planes to be able to identify them

    5. Plane perpendicular to y cuts at ?, 1, ? ? (0 1 0) plane

    8. Planes - conclusions 1 Miller indices define the orientation of the plane within the unit cell The Miller Index defines a set of planes parallel to one another (remember the unit cell is a subset of the “infinite” crystal (002) planes are parallel to (001) planes, and so on

    9. d-spacing formula For orthogonal crystal systems (i.e. ?=?=?=90?) :-

    10. A cubic crystal has a=5.2 Ĺ (=0.52nm). Calculate the d-spacing of the (1 1 0) plane

    11. Question 2 in handout: If a = b = c = 8 Ĺ, find d-spacings for planes with Miller indices (1 2 3) Calculate the d-spacings for the same planes in a crystal with unit cell a = b = 7 Ĺ, c = 9 Ĺ. Calculate the d-spacings for the same planes in a crystal with unit cell a = 7 Ĺ, b = 8 Ĺ, c = 9 Ĺ.

    12. X-ray Diffraction

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