The solubilities of copper and manganese in β-rhombohedral boron as determined in CuB ∼28 and MnB ∼23 by single-crystal diffractometry

Abstract

The structures of two crystals with the compositions CuB ∼28 and MnB ∼23 have been determined using single-crystal diffractometry. The compositions probably represent the maximum solubility of copper and manganese in β-rhombohedral boron. The space group is R 3m , and the hexagonal axes are a = 10.970 Å and c = 23.890 Å for CuB ∼28, and a = 10.988 Å and c = 23.994 Å for MnB ∼23. The three-dimensional boron network of β-rhombohedral boron is retained almost unchanged in the two compounds and the metal atoms are situated in holes in this network. In MnB ∼23 the manganese atoms partly occupy three crystallographic positions. In CuB ∼28 one of these positions is split up into two and the copper atoms consequently occupy four crystallographic positions.