Fr.: zone de Brillouin
Crystallography: One of the several regions which, in reciprocal space, represent the solution of the wave equations for the propagation of → phonons or electrons in solids. The first Brillouin zone is the Wigner-Seitz cell of the reciprocal lattice. It is a polyhedron obtained by connecting a lattice point to its first neighbors and drawing the planes perpendicular to these connecting lines and passing through their midpoints. The second Brillouin zone is obtained by a similar construction but the second-nearest neighbours.
After Léon Brillouin (1889-1969) French physicist; → zone.