Electron-phonon interaction in B 12 icosahedra

Abstract

By the interaction between electrons and pairs of phonons, which are the slightly modified breathing modes F 1u and F 2u of the free icosahedron, the electron trapping levels are generated, which are known to influence the properties of the boron-rich solids essentially. Depending on the number of phonon pairs involved up to six levels below the conduction band of β-rhombohedral boron occur, whose ionisation energies are multiples of 0.188(2) eV equal to the sum of the energies of the phonons involved. On β-rhombohedral boron and boron carbide is shown that in consequence of the formation of such levels the corresponding phonons in the lattice vibration spectrum are quenched.