New quasi-planar surfaces of bare boron

Boustani, İhsan

doi:10.1016/s0039-6028(96)00969-7

Cited by 229 publications

(176 citation statements)

References 39 publications

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“…The α-boron crystal consists of eight B 12 icosahedra centered on the vertices of a rhombohedral unit cell, whereas the main structural motif in the B 105 unit cell of the β-boron is a B 84 polyhedron, where a central icosahedron is surrounded by twelve B 6 pentagonal pyramids, and these large B 84 soccer ball clusters are placed at the points of the rhombohedral lattice [7]. Although the natural phases of bulk boron do not possess laminar structures, recent experimental studies [8] confirmed the existence of quasiplanar clusters of 10-15 B atoms which have been previously predicted by first principle calculations [9]. Furthermore, single walled boron nanotubes (SWBNTs) have also been declared beforehand by Boustani and coworkers [10][11][12][13] which have also been synthesized experimentally [14,15] a few years ago with a radius of nearly 18Å, after the fabrication of crystalline [16] and amorphous [17] boron nanowires with diameters as small as 20 nm.…”

Section: Introductionmentioning

confidence: 64%

“…Although the binding energy (5.97 eV) of the flat triangular plane (Fig. 1a) is not as low as that of the hexagonal sheet, not only the degeneracy in the three possible σ-bond directions of the structure [29] but also the fact that it does not obey the Aufbau principle [9], which states that stable boron clusters can be constructed from only two basic pentagonal pyramidal B 6…”

Section: A Properties Of B Sheets and Swbntsmentioning

confidence: 97%

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Free standing double walled boron nanotubes

Sebetci¹,

Mete²,

Boustani³

2008

Journal of Physics and Chemistry of Solids

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Based on density functional calculations we propose stable structures of free standing double walled boron nanotubes in the form of two single walled boron nanotubes inside one another.Puckering of the boron sheets allows the inner atoms of the outer wall and outer atoms of the inner wall to be matched giving sp-type hybrid σ bonding between the walls. The structural stability, in the case of double walled tubes, increases as the bond interaction between the walls strengthens.All the optimized structures reported in this study are electronically conducting in good agreement with the previously calculated metallic behavior of the experimentally observed single walled boron nanotubes.

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Section: Introductionmentioning

confidence: 64%

Section: A Properties Of B Sheets and Swbntsmentioning

confidence: 97%

Free standing double walled boron nanotubes

Sebetci¹,

Mete²,

Boustani³

2008

Journal of Physics and Chemistry of Solids

Self Cite

View full text Add to dashboard Cite

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“…4,15,16 Using ab initio structural optimization methods for solid systems we could finally discriminate among different structure models for layered boron compounds and establish a simple model for a broad and stable BS.…”

Section: 11mentioning

confidence: 99%

“…4. We repeated the puckering periodically in a triangular supercell containing 16 atoms (see (see Fig.…”

Section: A Finding a Structure Modelmentioning

confidence: 99%

Broad boron sheets and boron nanotubes: Anab initiostudy of structural, electronic, and mechanical properties

2006

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Based on a numerical ab initio study, we discuss a structure model for a broad boron sheet, which is the analog of a single graphite sheet, and the precursor of boron nanotubes. The sheet has linear chains of sp hybridized σ bonds lying only along its armchair direction, a high stiffness, and anisotropic bonds properties. The puckering of the sheet is explained as a mechanism to stabilize the sp σ bonds. The anisotropic bond properties of the boron sheet lead to a two-dimensional reference lattice structure, which is rectangular rather than triangular. As a consequence the chiral angles of related boron nanotubes range from 0• to 90• . Given the electronic properties of the boron sheets, we demonstrate that all of the related boron nanotubes are metallic, irrespective of their radius and chiral angle, and we also postulate the existence of helical currents in ideal chiral nanotubes. Furthermore, we show that the strain energy of boron nanotubes will depend on their radii, as well as on their chiral angles. This is a rather unique property among nanotubular systems, and it could be the basis of a different type of structure control within nanotechnology.

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“…The hexagonal graphitic BS was found to be unstable [11,18]. Based on extensive theoretical studies of boron clusters [11,12,13,14,15], an Aufbau principle was proposed whereby the most stable structures should be composed of buckled triangular motifs [12] . Experiments on small clusters of 10-15 atoms support this view [16].…”

mentioning

confidence: 99%

Novel Precursors for Boron Nanotubes: The Competition of Two-Center and Three-Center Bonding in Boron Sheets

2007

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We present a new class of boron sheets, composed of triangular and hexagonal motifs, that are more stable than structures considered to date and thus are more likely to be the precusors of boron nanotubes. We describe a simple and clear picture of electronic bonding in boron sheets and highlight the importance of three-center bonding and its competition with two-center bonding, which can also explain the stability of recently discovered boron fullerenes. Our findings call for reconsideration of the literature on boron sheets, nanotubes and clusters.PACS numbers: 73.63.Fg All boron nanotubes (BNT), regardless of diameter or chirality, are predicted to be metallic and have large densities of states (DOS) at their Fermi energies (E F ) [1]. In contrast, carbon nanotubes (CNT) can be semiconductors or metals with small DOS at their E F . Metallic CNT are used widely to study one-dimensional (1D) electronics [2,3] and are superconducting at low temperatures [4,5]. Due to the larger DOS, BNT should be better metallic systems for 1D electronics and may have higher superconducting temperatures than CNT.Recent experiments have fabricated boron nanotubular structures both as small clusters [6] and long, 1D geometries [7]. Understanding the properties of BNT is crucial for realizing their applications. For CNT, it has been fruitful to study two-dimensional (2D) graphene: e.g., many properties of CNT are derived directly from graphene [8,9]. For boron, however, no 2D planar structure exists in its crystals which are built from B 12 icosahedra [10]. Researchers have proposed several 2D boron sheets (BS). The hexagonal graphitic BS was found to be unstable [11,18]. Based on extensive theoretical studies of boron clusters [11,12,13,14,15], an Aufbau principle was proposed whereby the most stable structures should be composed of buckled triangular motifs [12] . Experiments on small clusters of 10-15 atoms support this view [16]. A recent study of many possible sheet structures found, again, the buckled triangular arrangement to be most favorable [17]. Hence, 2D triangular BS have been studied and used to construct BNT [18,19,20].In this Letter, we present a class of boron sheets that are more stable than the currently accepted ones. We describe their structures, energetics, electronic states, and provide a clear picture of the nature of their bonding that clarifies their stability. We also show that clusters with these structures are competitive with or more favorable than those considered to date. Our findings have important consequences for understanding and interpreting the properties of these systems. For example, the unusual stability of B 80 fullerenes [21] can be explained by our bonding picture. Hence, in our view, it is necessary to reconsider previous work in this general field.We use Density Functional Theory [22,23] within the ab initio supercell planewave pseudopotential total energy approach [24]. Calculations are done by PARATEC [25]. We use both the local density approximation (LDA) [23,26] and the generalize...

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New quasi-planar surfaces of bare boron

Cited by 229 publications

References 39 publications

Free standing double walled boron nanotubes

Free standing double walled boron nanotubes

Broad boron sheets and boron nanotubes: Anab initiostudy of structural, electronic, and mechanical properties

Novel Precursors for Boron Nanotubes: The Competition of Two-Center and Three-Center Bonding in Boron Sheets

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