Diamond subhydride: unraveling the mystery of “n-diamond”

Abstract

The carbonaceous structure named “n-diamond” is often obtained in experiments. It differs from pure diamond by forbidden reflections in the electron diffraction pattern. We suppose that this structure is not pure carbon, but a 3D polymeric hydrocarbon. We propose a crystal structure (called diamond subhydride due to the deficiency of hydrogen atoms) that can reproduce at some degree the high-angle diffraction pattern and the peculiarities of the electron energy loss spectrum observed for “n-diamond”. This structure is a semiconductor with a rather low (in comparison with diamond) calculated band gap, 2.18 eV, and possesses comparatively high stiffness, B = 121 GPa. Taking into account its low weight (approximately half of that of diamond) it could find practical application.