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Elementary Crystallography. Or, driving yourself crazy. Definition of a Crystal.
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Elementary Crystallography Or, driving yourself crazy
Definition of a Crystal A crystal or crystalline solid is a solid material, whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is crystallography
Definition of a Unit Cell For any given lattice, a unit cell can be defined as the smallest portion of the lattice that can be repeated indefinitely to form it. A lattice is defined as a pattern that repeats a motif by repeated translations through an interval t.
Escher 2d lattice Find the unit cell
Symmetry Operations 1. Translation 2. Rotation 3. Reflection 4. Inversion 5. Glide
Rotation Nomenclature A2 2-fold A3 3-fold A4 4-fold A6 6-fold
The previous were examples in 2 dimentions What happens in 3D We will look at a few models
Compound operations 1. screw axis t plus rotation 2. Glide plane t plus reflection 3. Roto-inversion (this is where we have fun)