Stable Boron Sheet Research Articles

A Density Functional Theory Study of New Boron Nanotubes

Abstract Using first-principles calculations, a series of new boron nanotubes (BNTs), which show various electronic properties, were theoretically predicted. Stable nanotubes with various chiral vectors and diameters can be formed by rolling up the boron sheet with relative stability [H. Tang and S. I. Beigi, Phys. Rev. B 82, 115412 (2010).]. By increasing the diameter for BNT, the stability is enhanced. The calculated density of states and band structures demonstrate that all the predicted BNTs are metallic, regardless of their diameter and chirality. The multicentre chemical bonds of the relatively stable boron sheet and BNTs are analysed using the deformation electron density. Within our study, the BNTs all have metallic conductive characteristics, in addition to having a low effective quality and high carrier concentration, which are very good nanoconductive material properties and could be combined to form high-power electrodes for lithium-ion batteries such as those used in many modern electronics.

Ultrahigh-Capacity Molecular Hydrogen Storage of a Lithium-Decorated Boron Monolayer

Recently, a novel boron monolayer with the “hexagon holes” density of η = 1/8 was repeatedly predicted to be the most stable boron sheet in different literatures. Its fascinating porous characteristic structure and sufficient surface space seem attractive and motivate researchers to perform further investigation about it. Herein, we demonstrated that the Li-decorated 1/8-boron monolayer is a kind of ultrahigh capacity hydrogen storage medium. We also established that Li atoms can be attached above the centers of the hexagonal holes in the novel 1/8-boron monolayer due to the charge transfer from Li atoms to boron atoms, and the electric field induced by the positive charged Li atoms attracts and polarizes the H2 molecules and makes the binding strong enough for potential applications to store H2 molecules but not dissociate them. Detailed calculations showed that the two-sided Li-decorated 1/8-boron monolayer has an ultrahigh hydrogen storage capacity averagely to bind up to four H2 molecules for each Li ...

Binary nature of monolayer boron sheets from ab initio global searches

Boron could be the next element after carbon to form two-dimensional monolayer structures. Using the ab initio global searches, we found all low-lying monolayer boron sheets with 1-4 hexagonal holes in each unit cell. The two most stable boron sheets are composed of two kinds of elementary units with isolated-hexagon and twin-hexagon holes, respectively, so that the boron sheets are binary structures in nature. Detailed structural analyses indicate that there exist two types of close-lying stable monolayer boron sheets, revealing the polymorphism of boron sheet. These binary monolayer boron sheets are expected to serve as precursors to build various boron nanotubes, boron fullerenes, and other boron-based low-dimensional nanomaterials.

Prediction of Two-Dimensional Boron Sheets by Particle Swarm Optimization Algorithm

We searched for two-dimensional metastable boron sheets by using the particle swarm optimization algorithm combined with first-principles methods. We present several possible boron sheets composed of triangular and hexagonal motifs. The calculated total energy shows that these boron sheets are less stable than α-sheet and two recently predicted 1/8 and 2/15 B-layers. The energy difference between the new proposed struc-1/8 boron sheet and the known α-sheet, 1/8 and 2/15 B-layers, is less than 0.01 eV/atom. The calculated total density states of these boron sheets show that they are metallic. The multicenter chemical bonds of the relatively stable boron sheets are analyzed using the electron localization function. Because two-dimensional sheets are the building blocks of corresponding nanotubes and fullerenes, the proposed metastable boron sheets, not only with the most stable boron sheets, are expected to advance further investigations and understandings on boron nanotubes and fullerenes.

低维硼碳纳米材料第一原理研究

We have reviewed our recent researches on the boron and carbon nanostructures in this paper. We show that the stable boron sheet, nanotubes, and nanoribbons have a rich variety of electronic properties. For boron carbide nanostructures, such as the ordering BC₃, BC₅ and BC₇ sheets, we found that the hydrogenation and defects could lead to rich electronic and magnetic properties. The boron and carbon nanostructures may have the potential applications in the nanoscale devices in the future.

A New Class of Boron Nanotube

The configurations, stability and electronic structures of a new class of boron sheet and related boron nanotubes are predicted within the framework of density functional theory. This boron sheet is sparser than those of recent proposals. Our theoretic results show that the stable boron sheet remains flat and is metallic. There are bands similar to the pi-bands in graphite near the Fermi level. Stable nanotubes with various diameters and chiral vectors can be rolled from the sheet. Within our study, only the thin (8, 0) nanotube with a band gap of 0.44 eV is semiconducting, while all the other thicker boron nanotubes are metallic, independent of their chirality. It indicates the possibility, in the design of nanodevices, to control the electronic transport properties of the boron nanotube through the diameter.

The transport properties of boron nanostructures

The transport properties of devices made from boron nanoribbons with different sizes and sandwiched between metallic electrodes are investigated. The boron nanoribbons are constructed from the stable boron sheet. In general the transport properties of the different sizes differ from each other. In particular, the transport properties of the boron ribbons show strong dependence on their width and the gap of peak is inversely proportional to its width. As a consequence the I-V characteristics are rather different in the different sizes and the wider boron ribbon greatly enhances the conductance through the device.

Boron fullerenes: FromB80to hole doped boron sheets

We demonstrate the existence of a family of stable boron fullerenes containing $80{n}^{2}$ atoms that is related to the family of $60{n}^{2}$ carbon icosahedral fullerene series and is compatible with the recently proposed stable boron sheets composed of triangular and hexagonal motifs. All electron density-functional calculations on the ${\text{B}}_{320}$, ${\text{B}}_{720}$, ${\text{B}}_{1280}$, and ${\text{B}}_{2000}$ confirm their stability and show that the quantum size effects open up electronic band gaps in the boron fullerenes at ${\text{B}}_{1280}$. Boron fullerenes below ${\text{B}}_{2000}$ have valence electronic structure identical to their corresponding carbon cousins from $60{n}^{2}$ family.

Electronic structures of boron nanoribbons

Using first principles calculations, we investigate the electronic properties of boron nanoribbons. The boron nanoribbons are constructed from the stable boron sheet. The bare boron nanoribbons with different edges are metals. The boron nanoribbons with two-hydrogen passivated on the zigzag edges become semiconductors and are more stable than the one-hydrogen passivated ones. The band gaps are within the range of 0.5eV and there is an oscillatory variation in the band gaps with the change of widths due to the even-odd number of nanoribbon widths.

Face-centered-cubicB80metal: Density functional theory calculations

By means of ab initio calculations within the density functional theory, we have found that ${\text{B}}_{80}$ fullerenes can condense to form stable face-centered-cubic (fcc) solids. It is shown that when forming a crystal, ${\text{B}}_{80}$ cages are geometrically distorted, the ${\text{I}}_{h}$ symmetry is lowered to ${\text{T}}_{h}$, and four boron-boron chemical bonds are formed between every two nearest neighbor ${\text{B}}_{80}$ cages. The cohesive energy of ${\text{B}}_{80}$ fcc solid is 0.23 eV/atom with respect to the isolated ${\text{B}}_{80}$ fullerene. The calculated electronic structure reveals that the fcc ${\text{B}}_{80}$ solid is a metal. The predicted solid phase would constitute a form of pure boron and might have diverse implications. In addition, a simple electron counting rule is proposed, which could explain the stability of ${\text{B}}_{80}$ fullerene and the recently predicted stable boron sheet.

Ab initioprediction of stable boron sheets and boron nanotubes: Structure, stability, and electronic properties

Using first-principles calculations, we predict a novel stable boron sheet and boron nanotubes which show various electronic properties. The boron sheet is flat and has the structure that the two centers of each three hexagons in the hexagonal lattice are filled with additional atoms, which preserves the symmetry of the triangular lattice. The boron sheet is metal, and there are bands similar to the $\ensuremath{\pi}$ bands in the graphene near the Fermi level. Rolled from the sheet, the nanotubes with diameter larger than $17\phantom{\rule{0.3em}{0ex}}\mathrm{\AA{}}$ are metals. Smaller nanotubes are semiconductors with the gap decreasing as the diameter and chiral angle increase.

Boron Fullerenes: A First-Principles Study

A family of unusually stable boron cages was identified and examined using first-principles local-density functional method. The structure of the fullerenes is similar to that of the B12icosahedron and consists of six crossing double-rings. The energetically most stable fullerene is made up of 180 boron atoms. A connection between the fullerene family and its precursors, boron sheets, is made. We show that the most stable boron sheets are not necessarily precursors of very stable boron cages. Our finding is a step forward in the understanding of the structure of the recently produced boron nanotubes.