Towards Free Standing Lonsdaleite and Diamond Few Layers: The Nitrogen Effect

摘要： Strong, directional, N bonding led surface stabilization is induced to obtain free standing two dimensional layered assemblies of Lonsdaleite and diamond phase carbon by surface termination at 3 coordinated C sites. These assemblies have strong bonding and surface N lone pair induced self protection and achieves respective bulk-like electronic, mechanical and crystallographic properties at as low as 7 atomic layer thickness. Lonsdaleite phase sub-nano thickness free standing as small as 3 layered assembly shows bulk-like thermal stability up to 2900K. Size con?nement e?ect dominates up to four layered assembly and then electronic and crystallographic properties are dominated by bulk stabilization which saturates towards respective bulk-like features from 7 layer assembly. Similarly, free standing hybrid assemblies of Lonsdaleite phase carbon with BeF (C5NBeF) and BS (C5NBS) layer are also proposed along with low symmetric Cm-C3N4 layered assembly. The combination of N and O is shown to stabilize surface of nanodiamond but shows signi?cant variation in structural and electronic properties, which are principally govern by con?nement e?ect because of weak surface stabilization. Our results proposes that, in principle, two dimensional free standing layered assemblies of the sp3 hybridized phases of carbon with surface terminated by only 3 coordinated C sites, can be stabilized and engineered by substitutional doping of N, and in some cases respective bulk-like electronic and crystallographic properties at nano size can be achieved.