If we take the square unit cell S2 and stack it, we produce this square lattice.
Notice that once we begin stacking the unit cells, we never change the orientation of any subsequent unit cells as they stack.
In other words, once the orientation of a unit cell is determined, all unit cells within that lattice have the same orientation.
The hexagonal unit cell H1 gives a different arrangement of circles.
In the figures below we have created lattices from unit cells. It is the stacking which creates lines and cavities which are not immediately obvious from looking at the unit cells.
S1 unit cell S1 lattice
We can look at the S1 lattice as alternating staggered rows of solid and empty circles - both horizontally and vertically.
We can also see it as diagonal rows of alternating circles.
S3 unit cellS3 lattice
We can see lattice S3 as different diagonal lines of atoms, or horizontal
rows, or vertical columns. If we rotate the entire lattice 90 degrees we
see an identical pattern. This is a property of a square lattice.
If we rotate the entire lattice 60 degrees or 120 degrees we
see an identical pattern. This is because the unit cell is hexagonal.
In the H3 lattice, the pattern of lines is the same (every 60 degrees),
but each line contains the repeating sequence (pink- purple-purple).
Click here to go to the next page.
Structure of Crystals
From Unit Cell to Lattice
From Lattice to Unit Cell
Packing & Geometry
Simple Cubic Metals
Close Packed Structures
Body Centered Cubic
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