Abstract
Boron, a nearest-neighbor of carbon, is possibly the second element that can possess free-standing flat monolayer structures, evidenced by recent successful synthesis of single-walled and multiwalled boron nanotubes (MWBNTs). From an extensive structural search using the first-principles particle-swarm optimization (PSO) global algorithm, two boron monolayers (α 1- and β 1-sheet) are predicted to be the most stable α- and β-types of boron sheets, respectively. Both boron sheets possess greater cohesive energies than the state-of-the-art two-dimensional boron structures (by more than 60 meV/atom based on density functional theory calculation using PBE0 hybrid functional), that is, the α-sheet previously predicted by Tang and Ismail-Beigi and the g 1/8- and g 2/15-sheets (both belonging to the β-type) recently reported by Yakobson and co-workers. Moreover, the PBE0 calculation predicts that the α-sheet is a semiconductor, while the α 1-, β 1-, g 1/8-, and g 2/15-sheets are all metals. When two α 1 monolayers are stacked on top each other, the bilayer α 1-sheet remains flat with an optimal interlayer distance of ∼3.62 Å, which is close to the measured interlayer distance (∼3.2 Å) in MWBNTs.
Original language | English (US) |
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Pages (from-to) | 7443-7453 |
Number of pages | 11 |
Journal | ACS Nano |
Volume | 6 |
Issue number | 8 |
DOIs | |
State | Published - Aug 28 2012 |
Keywords
- boron monolayer sheet
- double-walled boron nanotube
- hybrid density functional
- interlayer distance
ASJC Scopus subject areas
- Materials Science(all)
- Engineering(all)
- Physics and Astronomy(all)