Structural aspects and stability of superconducting nanotubular magnesium boride: Large diameter multiwall nanotubes of MgB2

Based on theoretical study we demonstrate that stable MgB2 nanotubes are not derived from mixed triangular-hexagonal structural motif of single layer sheet, which is supposed to be 2D precursor form of all boron nanotubes. Most stable are MgB2 multiwall nanotubular structures derived from multilayer MgB2 slab with honeycomb B-network in hexagonal lattice. Results of ab initio study of multilayer slabs of MgB2 show that already 25-layers slab approaches stability of bulk MgB2. Critical parameter of corresponding multi-wall nanotubes is the inner diameter. Calculated value is ~ 32.6nm, independent on number of walls. The outer diameter of 25-walls nanotube is ~ 51 nm, and terminal Mg atoms are placed over the outer tubular surface. We show here that electronic band structure of MgB2-multiwall nanotube corresponds to band structure character and topology of superconducting bulk MgB2. Obtained results confirm that quazi-1D superconductor - MgB2MWNT is a stable structure and can be produced as experimentally indicated by Zhou et al. [Materials Letters 63, 1680 (2009)].