- Practical Electron Microscopy and Database -
- An Online Book -
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|This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.|
A lattice point is known as a motif or basis. We can obtain a crystal structure by combining the lattice with the motif (i.e., crystal structure = lattice + motif). Figure 3076a shows a periodic pattern consisting of a two-dimensional (2-D) net and a motif. The motif is arranged symmetrically and is repeated at each point of the 2-D net to create the periodic pattern, and thus the lattice structure is also symmetric.
Figure 3076a. (a) A 2-D net, (b) A motif, and (c) Formed periodic pattern (2-D lattice structure).
Note that all lattice points must be identical. The unique arrangements of lattice points are so-called Bravais lattice, named after Auguste Bravais.
The number of the lattice points per unit cell in 2-D lattices can be given by,
Figure 3076b. Lattice points inside the unit cell and at the corners in 2-D lattices.
On the other hand, the number of the lattice points per unit cell in 3-D lattices can be given by,
Figure 3076c. Lattice points inside the unit cell and at the corners in 3-D lattices.
Table 3076. Typical lattices and their basis.
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