Recent developments in the structural crystallography of boron and the higher borides

This paper reviews structural studies of boron and boron-rich borides over the last decade using as a framework the classification scheme proposed by Matkovich and Economy. Chemical bonding in boron polyhedral units and the packing of these units in normal 3D space lattices are described with emphasis on stabilization effects that may be produced by impurity elements Potentially useful areas for structural work with several new scattering and spectroscopic techniques are suggested. The paper concludes with a discussion of possible connections between boride crystal chemistry and the developing subject of quasicrystalline structures