Structure of the boron nitride E-phase: Diamond lattice of B12N12 fullerenes

The molecular and crystal structures of the boron nitride E-phase are determined. Analysis of all calculated for the first time main peaks of X-ray diffraction patterns (6.28, 3.85, 3.28, 2.72, 2.50, 2.22, 2.09, 1.92 Å) in comparison with experimental ones indicates that E-BN has the diamond-type lattice (the cell constant a = 10.877 Å, the space group Fd3m or Oh7) formed with Th symmetry B12N12 molecules copolymerized by the hexagonal faces. Hence we propose to mean “extradiamond” term instead of “explosion” term in the E-phase name. Extradiamond-B12N12 has a framework type of faujasite and can be referred to as [B12N12]-FAU zeolite. Ideal crystal of E-BN has 192 atoms per unit cell and theoretical density of 3.074 g/cm3.