Structural Defects of Some Icosahedral Boron-Rich Solids and Their Correlation with the Electronic Properties

For beta-rhombohedral boron and boron carbide, the hitherto best-investigated icoasahedral boron-rich solids, the concentrations of structural defects and electronic gap states are quantitatively correlated. In this way the theoretically determined valence electron deficiencies are exactly compensated, and the metallic character of these solids resulting in the theoretical calculations on hypothetical idealized structures is changed to the experimentally proved semiconducting behavior. Obviously, the structural defects in these crystals are the necessary consequence of the valence electron deficiency. It is suggested that this correlation holds for icosahedral boron-rich solids in general