arXiv subjects

P. Banacky

Publications and source records attributed to P. Banacky.

2 recordsLinked to original sources

arXiv2015

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

Based on a theoretical study, we demonstrated that magnesium boride nanotubes can reach the same stability as bulk MgB2 structure. However, most stable nanotubular forms are not structurally derived from mixed triangular-hexagonal structural motifs of a single layer sheet, which is thought to be the 2D precursor form of all boron nanotubes. MgB2 multiwall nanotubular structures that are derived from multilayer MgB2 slabs with honeycomb B-networks in hexagonal lattices are more stable. The results of an ab initio study of multilayer slabs of MgB2 show that a 25-layer slab approaches the stability of bulk MgB2. The critical parameter of the corresponding multiwall nanotubes is the inner diameter; the calculated value is ~ 32.6nm, which is independent of the number of walls. The outer diameters of 25-wall nanotubes are ~ 51 nm, and terminal Mg atoms are located on the outer surfaces of the nanotubes. The electronic band structures of MgB2-multiwall nanotubes (MgB2MWNT) correspond to the band structure character and topology of superconducting bulk MgB2. The results confirm that the quasi-1D superconductor MgB2MWNT is a stable structure and can be synthesized.

cond-mat.mes-hall↗

arXiv2012

Toward possibility of high-temperature bipolaronic superconductivity in boron tubular polymorph: Theoretical aspects of transition into anti-adiabatic state

Large diameter single-wall boron nanotubes (SWBNT) produced by 2%Mg-mesoporous Al2O3 catalysis show diamagnetic transition at ~ 40 K and ~ 80 K, which is a serious indication for possible superconductivity (J.Phys.Chem.C113, (2009) 17661). Theoretical study which explains or disproves possibility of superconductivity in boron is so far absent, however. Here we apply first-principles formulation of nonadiabatic theory of electron-vibration interactions in study of band structure of boron nanotubes. The ab initio results show that electron-vibration coupling induces in SWBNT with diameter larger than 15 Å transition into anti-adiabatic ground state at distorted-fluxional geometry. Thermodynamic and magnetic properties of anti-adiabatic ground state imply possibility of bipolaronic superconductivity. Calculated critical temperature Tc of large diameter SWBNT is 39 K and inclusion of Mg into a tube increases Tc up to 70-90 K. Presence of Al in SWBNT suppress superconductivity and a tube remains metallic down to 0 K. Superconducting properties could established boron nanotubes superior material for nanotechnology.

cond-mat.supr-con↗