New boron based nanostructured materials

Boustani, İhsan; Quandt, Alexander; Hernández, Eduardo; Rubio, Ángel

doi:10.1063/1.477976

Cited by 268 publications

(257 citation statements)

References 32 publications

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“…As was reported in the paper by Boustani et al [16] preliminary experimental results for pure-boron systems seem to confirm the existence of boron sheets. We will consider here a purely planar boron configuration and apply the simplest possible theories to extract the main features of the DOS which arise from topological aspects.…”

Section: Pentagonal Defects and Curvaturesupporting

confidence: 81%

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Topology, Connectivity, and Electronic Structure ofCandBCages and the Corresponding Nanotubes

Leys

Amovilli

March

2003

J. Chem. Inf. Comput. Sci.

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After a brief discussion of the structural trends which appear with increasing number of atoms in B cages, a one-to one correspondence between the connectivity of B cages and C cage structures will be proposed. The electronic level spectra of both systems from Hartree-Fock calculations is given and discussed. The relation of curvature introduced into an originally planar graphitic fragment to pentagonal 'defects' such as are present in buckminsterfullerene is also briefly treated.A study of the structure and electronic properties of B nanotubes will then be introduced. We start by presenting a solution of the free-electron network approach for a 'model boron' planar lattice with local coordination number 6. In particular the dispersion relation E(k) for the π−electron bands, together with the corresponding electronic Density Of States (DOS), will be exhibited. This is then used within the zone folding scheme to obtain information about the electronic DOS of different nanotubes obtained by folding this model boron sheet.To obtain the self-consistent potential in which the valence electrons move in a nanotube, 'the March model' in its original form was invoked and results are reported for a carbon nanotube.Finally, heterostructures, such as BN cages and fluorinated buckminsterfullerene, will be briefly treated, the new feature here being electronegativity difference. I. BACKGROUND AND OUTLINEThe continuing usefulness of models of π−electrons in conjugated systems, for example that of Hückel [1], testifies to the importance of geometry and connectivity in determining electronic structure. There has, indeed, been renewed interest in this area, due to the potential for technology of nanostructures [2].Therefore, in the present study of C and B cages, and the corresponding nanotubes, we shall not hesitate in presenting the simplest possible approaches to electronic structure of the π−electrons when these highlight the importance of topology and connectivity. However, it will also prove useful in the course of the discussion, to refer briefly to calculations of Hartree-Fock quality that have been carried out on a variety of B [3] and C [4] cages.The outline of the present study is then as follows. Section II below exposes, essentially via Euler's theorem, a one-to-one correspondence between the connectivity of C and B cages. For example, C 60 naturally leads to a B 32 cage. Considerable similarities between the electronic level spectra of both systems are reported. Also briefly discussed is the matter of pentagonal 'defects' and the approximate relation to curvature of originally planar graphitic fragments. This is illustrated by reference to the recent Hartree-Fock calculations on B cages of intermediate size already mentioned.This discussion involving planar fragments, leads into Section III which presents a study of the structure and the electronic properties of boron nanotubes obtained by folding planar sheets of boron atoms. We utilize a (quantum) model akin to Kirchoff's laws of electrical circuits, where...

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Section: Pentagonal Defects and Curvaturesupporting

confidence: 81%

“…(16). For a general choice of n and m, the number of atoms in the unit cell of the nanotube, and correspondingly the number of 1D dispersion relations gets very large compared to the simpler (n, n) and (n, 0) cases and is less insightfull.…”

Section: E 1d Energy Bands For General Chiral Symmetrymentioning

confidence: 99%

Topology, Connectivity, and Electronic Structure ofCandBCages and the Corresponding Nanotubes

Leys

Amovilli

March

2003

J. Chem. Inf. Comput. Sci.

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“…Several models for boron sheets and nanotubes (BNTs) with different underlying lattice structures have been proposed [8][9][10][11][12][13] and first successes in growing pure BNTs were reported. [14][15][16] In contrast to carbon nanotubes, which can be either semiconducting or metallic depending on their diameter and chiralities, BNTs are predicted to be metallic only [8][9][10] and highly conductive. 17,18 For small-diameter BNTs related to the α-sheet (diameter < 1.7 nm), some density functional theory (DFT) calculations predict that the nanotubes are semiconducting due to a curvature-induced out-of-plane buckling of certain atoms.…”

Section: Introductionmentioning

confidence: 99%

Unveiling the Atomic Structure of Single‐Wall Boron Nanotubes

Kunstmann

Bezugly

Rabbel

et al. 2014

Adv Funct Materials

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Despite recent successes in the synthesis of boron nanotubes (BNTs), the atomic arrangement of their walls has not yet been determined and many questions about their basic properties do remain. Here, we unveil the dynamical stability of BNTs by means of firstprinciples molecular dynamics simulations. We find that free-standing, single-wall BNTs with diameters larger than 0.6 nm are thermally stable at the experimentally reported synthesis temperature of 870 • C and higher. The walls of thermally stable BNTs are found to have a variety of different mixed triangular-hexagonal morphologies. Our results substantiate the importance of mixed triangular-hexagonal morphologies as a structural paradigm for atomically thin boron.

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“…1, 2 Boron is characterized by a short covalent radius and has the tendency to form strong and directional chemical bonds. 1,2 These characteristics lead to a large diversity of boron nanostructures -clusters, 3,4,5,6,7 nanowires, 8 and nanotubes 9,10 -that have already been observed.…”

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confidence: 99%

The planar-to-tubular structural transition in boron clusters from optical absorption

Marques

Botti

2005

The Journal of Chemical Physics

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The optical response of the lowest energy isomers of the B20 family is calculated using timedependent density functional theory within a real-space, real-time scheme. Significant differences are found among the absorption spectra of the clusters studied. We show that these differences can be easily related to changes in the overall geometry. Optical spectroscopy is thus an efficient tool to characterize the planar to tubular structural transition, known to be present in these boron based systems.PACS numbers: 78.67. Bf, 64.70.Nd, 71.15.Mb For the past years, boron nanostructures have attracted the attention of both theoretical and experimental physicists. This is due to the remarkable properties of boron, that make it an unique element in the periodic table, with important technological applications. 1,2 Boron is characterized by a short covalent radius and has the tendency to form strong and directional chemical bonds. 1,2 These characteristics lead to a large diversity of boron nanostructures -clusters, 3,4,5,6,7 nanowires, 8 and nanotubes 9,10 -that have already been observed.Many experimental studies of small boron-based clusters have been performed in the last decade, namely using mass and photo-electron spectroscopies. 3,4,5,7 However, we still have very limited information regarding the geometries and electronic properties of these systems. From the theoretical point of view, there have been extensive ab initio quantum chemical and density functional calculations about the structural properties of neutral, 3,5,7,11,12,13,14,15,16 cationic, 15,17,18 and anionic clusters. 5,7 The findings were fairly surprising. In fact, bulk boron appears in several crystalline and amorphous phases, the best know of which are the α-and β-rombohedral, and the α-tetragonal, also known as low temperature or red boron. In these three phases, boron is arranged in B 12 icosahedra 1,19,20 (in the α-tetragonal phase these icosahedra are slightly distorted). However, the small clusters appear in four distinct shapes: 16 convex, spherical, quasi-planar, and nanotubular -totally unrelated to the B 12 icosahedra.The most stable members of the B n family with n 20 are known to be planar. 3,5,11,12,13,14,15 Recent calculations showed that B n clusters with n = 24 and n = 32 prefer tubular structures. 16 In a recent study 7 Kiran et al. placed the transition between these two topologies at n = 20. However, their results were not totally conclusive: while the theoretical calculations (using density functional theory at the B3LYP/6-311+G * level) yielded a double ring arrangement as the lowest energy isomer of B 20 and B − 20 , the experimental photo-electron spectra of anionic aggregates of the same size were only compatible with planar structures. Such a incongruity can be explained by the difficulties associated both to the experimental and numerical techniques. Experimentally, the clusters were produced by laser evaporation of a disk target, with the formation of the fragments being mainly controlled by kinematics. The situation is...

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New boron based nanostructured materials

Cited by 268 publications

References 32 publications

Topology, Connectivity, and Electronic Structure ofCandBCages and the Corresponding Nanotubes

Topology, Connectivity, and Electronic Structure ofCandBCages and the Corresponding Nanotubes

Unveiling the Atomic Structure of Single‐Wall Boron Nanotubes

The planar-to-tubular structural transition in boron clusters from optical absorption

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