Raman spectroscopy of B12As2 and B12P2 up to 120 GPa: Evidence for structural distortion
Résumé
Boron and boron-rich solids are materials with unusual structures. B12 distorted icosahedra are the primary building blocks of pure boron and many boron-rich solids. B atoms within icosahedra participate in strong covalent bonds with neighboring atoms in adjacent icosahedra and other struc- tural elements. As a consequence of this bonding, these com- pounds are very stable, with a melting temperature up to 2700 K. The bonding within icosahedra is metallike: internal bonding electrons are delocalized over the surface of each icosahedron with densities that peak at the centers of the triangular faces formed by three neighboring boron atoms. Such distinctive bonding has some extremely interesting consequences, such as self-healing resistance to radiation damage.1 Hence, the stability range of icosahedrally builded compounds presents interest both from fundamental and ap- plication points of view.