lattice plane (crystal lattice plane)

Since in a crystal, the planes composed of atoms are aligned in parallel and with an equal distance, a crystal is regarded as an assembly of atomic planes. Further, in a crystal, atomic planes with different atomic positions and different atomic species can stack periodically (Fig. 1). Then, a series of equivalent planes is termed a “(crystal) lattice plane”. The distance between the neighboring equivalent planes is called the “spacing of the plane”. In a crystal, many sets of lattice planes with different orientations can be considered.
Diffraction spots, which appear due to diffraction of electrons by a crystal, can be considered as reflections of the electron beam from a series of crystal lattice planes. Thus, the indices of the diffraction spots correspond directly to the indices of the lattice planes.

Fig. 1. The crystal lattice planes of the body-centered cubic structure. Two types of crystal planes are periodically aligned in the transverse direction to form a crystal lattice. The positions of the atoms are different on the first and second planes.

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