Boron Nanotubes Research Articles

The effect of C, Si, N, and P impurities on structural and electronic properties of armchair boron nanotube

The structural and electronic properties of non-metal atoms (X = C, N, Si, P) doped (6,0) boron nanotube (BNT) have been considered in a systematic study by performing periodic spin polarized density functional theory (DFT) calculations. The studies showed that cylindrical shape of the nanotube is changed by doping, except for C substitution. Notably, all the substitution processes are endothermic and the C-substituted becomes energetically more stable than the other dopants. It is revealed that the C-doped BNT is semi-metal, whereas the nanotube in the presence of the other dopants remains semiconductor. Hence, the substitution is an effective way in narrowing band gap of the nanotube. Doping by N atom changes the band gap from indirect to direct, which can be suitable for optical applications. Thus, electronic structure of the tube has been controlled by type of the dopant atoms. Our study predicted that the BNTs in the presence of the dopants are promising candidate as interconnects for nano-devices as well as field emission devices.

Electronic transport properties of single-wall boron nanotubes**Project supported by the National Natural Science Foundation of China (Grant No. 51671114) and the Special Funding in the Project of the Taishan Scholar Construction Engineering and National Key Research Program of China (Grant No. 2016YFB0300501).

Electronic transport properties of single-wall boron nanotube (BNT) with different chiralities, diameters, some of which are encapsulated with silicon, germanium, and boron nanowires are theoretically studied. The results indicate that the zigzag (3,3) BNT has more electronic transmission channels than the armchair (5,0) BNT because of its unique structure distortion. Nanowires encapsulated in the BNT can enhance the conductance of the BNT to some extent by providing a significant electronic transmission channel to the BNT. The effect of the structure of nanowires and the diameter of BNTs on the transport properties has also been discussed. The results of this paper can enrich the knowledge of the electron transport of the BNT and provide theoretical guidance for subsequent experimental study.

Guest Editorial: A path through quantum crystallography: a short tribute to Professor Lou Massa

Professor Lou Massa’s contributions since the late 1960s to the founding of the field now known as “Quantum Crystallography” (QCr) are briefly described. The term itself has been coined in 1995 by L. Huang, L. Massa, and J. Karle (1985 Nobel Laureate in Chemistry). Originally, QCr referred to the Clinton-Massa’s iterative approach that, for the first time, delivered N-representable electron densities that are consistent with the observed structure factors. These densities satisfy, at once, experimental observation and the necessarily underlying quantum mechanical requirement of being derived from an antisymmetric wavefunction. The single-determinantal quantum mechanical structure Huang, Massa, and Karle (HMK) imposed in their original work can be extended to any method that uses MOs including CI or DFT, as they demonstrate in their papers. HMK use the Clinton-Massa method to reconstruct approximations to the first order reduced density matrix of large molecules in a piecemeal manner from computationally-tractable fragments. The idea was also adapted by J. Hernandez Trujillo and R. F. W. Bader in the context of the Quantum Theory of Atoms in Molecules (QTAIM). Massa et al. simplified and generalized this fragmentation method into what came to be known as the “Kernel Energy Method” (KEM) which delivers the properties of large molecules accurately, at a fraction of the computational time, and within any model chemistry as applications to DNA, tRNA, the proto-ribosome, insulin, and graphene, amply demonstrate. Lou Massa has also pushed the envelope in other directions as well. In 1992, he and W. Lipscomb (1976 Nobel Laureate in Chemistry) published several papers predicting the structure and stability of Boron nanotubes and boron fullurene 12 years before they were eventually synthesized in laboratories at Yale and at Brookhaven. More recently, in 2006 L. Massa, J. Karle, and A. Yonath (2009 Nobel Laureate in Chemistry) (MKY) proposed a startling alternative to the then widely-accepted mechanism of the peptide bond formation in the active site of the ribosome. In sharp contrast with the accepted “shuttle mechanism”, MKY’s “direct” mechanism is simpler and, importantly, reproduces the measured thermodynamic and kinetic parameters. Massa has also contributed to other domains, for example interstellar chemistry, and to the policy, history, and philosophy of science. His TV program and Oxford University Press book (both titled “Science and the Written Word”) represent an invaluable and candid documentation of some of the key discoveries in the words of a dozen Nobel Laureates and a constellation of scholars representing the Who’s Who of current science. It is with both admiration and affection that this paper (and this issue) is dedicated to Lou Massa, the person and the scientist.

Effect of boron impurity in a carbon nanotube superlattice

In this work, the influence of boron atom impurity is investigated on the electronic properties of a single-wall carbon nanotube superlattice which is connected by pentagon–heptagon topological defects along the circumference of the heterojunction of these superlattices. Our calculation is based on tight-binding [Formula: see text]-electron method in nearest-neighbor approximation. The density of states (DOS) and electronic band structure in presence of boron impurity has been calculated. Results show that when boron atom impurity and nanotube atomic layers have increased, electronic band structure and the DOS have significant changes around the Fermi level.

Prediction of Single-Wall Boron Nanotube Structures and the Effects of Hydrogenation

The unique electronic properties of boron nanotubes (BNTs) and hydrogenated BNTs (H-BNTs) lead to its potential applications in electrochemical and hydrogen storage. In the present work, the stability and electronic properties of single-wall BNTs and, particularly, the effects of hydrogenation on the structural and electronic features are investigated on the basis of the first-principles electronic calculations. It is interesting to find that hydrogenation can stabilize (m,0) BNTs with m being 7–13. In addition, H-BNTs can be either metallic or semiconducting depending on the diameter. In particular, electronic properties of (m,0) H-BNTs can also be engineered by exerting strain along the axial direction, as verified in the case of strained H-BNTs where a semiconductor–metal crossover was predicted at 3% tensile strain. Our results would drive more interesting studies on BNTs with different chiralities and chemical functionalizations.

Growth of single crystalline boron nanotubes in a Cu alloy

Herein, we report the successful synthesis of single crystalline boron nanotubes in a Cu alloy via a novel and simple direct melt reaction process.

On Multiple Zagreb Indices of Boron and Boron-α Nanotubes

On Multiple Zagreb Indices of Boron and Boron-<i>α</i> Nanotubes

The effect of MWCNT addition on superconducting properties of MgB2 fabricated by high-pressure combustion synthesis

We successfully prepared superconducting powders of magnesium diboride doped with carbon nanotubes by the method of combustion synthesis under high Ar pressure. Powders of magnesium, boron, and multi-walled carbon nanotubes (MWCNT) were used as starting materials. X-ray diffraction analysis showed the presence of MgB2 and MgO in combustion products. The temperature dependence of magnetization showed a sharp superconducting transition at around 38.5 K. The critical current density can be estimated from the hysteresis of magnetization curve by using the Bean’s formula. MgB2 doped with MWCNT (1%) showed the best value of high critical current density, 1.4 × 108 A/cm2 at 5 K, in zero magnetic fields.

Charge extracting buffer layers in bulkheterojunction organic solar cell

The effects of boron and nitrogen-doped carbon nanotubes (B- or N-CNTs) have been investigated as photoactive and charge extracting layer in bulk heterojunction organic solar cell composed of poly(3-hexylthiophene) [P3HT] and 1(3-methoxycarbonyl)propyl-1-phenyl-[6,6] C61 (PCBM). Two types of device configurations were employed by casting the doped CNTs close to either the hole or electron collecting electrodes next to a film of P3HT:PCBM blend. The electrical properties of OPV devices measured under standard 1.5 AM illumination suggest that those devices with B-CNTs layer close to the hole collecting electrode improved by 141 % while the devices with N-CNTs layer next to electron collecting electrode improved only by 38 %. The results are attributed to enhanced charge carrier’s transfer to the electrodes by reducing recombination at the interfaces. The doped CNTs layer near the photoactive medium of OPV is found to enhance device performance compared to the incorporation of CNTs in P3HT:PCBM blend.

Field emission characteristics of pristine and lithium-doped boron nanotubes: A theoretical study

First-principles calculations are used in order to investigate the electronic and field emission properties of capped (5, 5) and (9, 0) boron nanotubes (BNTs), which indicate that the electric currents of the (5, 5) and (9, 0) BNTs under an applied electric field are very close to those of carbon nanotubes, and pentagons and hexagons on the tips of the BNTs are the most possible spots for emitting tunneling electrons under an external electric field. In addition, the work functions of the (5, 5) and (9, 0) BNTs decrease linearly with applied electric fields. The significant influence of lithium adsorption on field emission characteristics of BNTs is also studied. The work functions of BNTs decrease distinctly after lithium adsorption, while the emission currents increase by a large margin. Moreover, the lithium adsorption can improve the electric conductivity of a mixture of BNTs.

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 ∼32.6 nm, 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.

Single-parameter model for multi-walled geometry of nanotubular boron

For designing devices based on nanotubular elemental boron with predetermined properties, it is important to have a reliable geometrical model of boron multi-walled nanotubes. We propose a model taking into account the following attributes of boron nanotubes: (i) defectiveness of tubular surfaces (buckling/puckering, presence of hexagonal vacancies), (ii) covalent bonding between the neighboring walls in multi-walled nanotubes and nanotubular bundles, and (iii) differences in the wall structures of single- and multi-walled nanotubes. This is a geometric model with a single structural parameter d – the average length of B–B bonds – which is based on the interpolation formulas for a nanotube radius and the 1D lattice constant. Within this model, boron nanotubes are not classified in the widely accepted fashion, i.e., in the same way as carbon nanotubes, but according to results of initial search for the boron nanotubes of reciprocal geometry of carbon nanotubes. The proposed model is tested for the value d ≈ 1.78 Å which corresponds to the equilibrium bond length according to the quasi-classical B–B pair potential. Estimates made for various bundle structures show that typically the concentrations of boron atoms are expected in the narrow range (1.6–1.8)·1023 cm−3.

Thermodynamics of the adsorption of flexible polymers on nanowires.

Generalized-ensemble simulations enable the study of complex adsorption scenarios of a coarse-grained model polymer near an attractive nanostring, representing an ultrathin nanowire. We perform canonical and microcanonical statistical analyses to investigate structural transitions of the polymer and discuss their dependence on the temperature and on model parameters such as effective wire thickness and attraction strength. The result is a complete hyperphase diagram of the polymer phases, whose locations and stability are influenced by the effective material properties of the nanowire and the strength of the thermal fluctuations. Major structural polymer phases in the adsorbed state include compact droplets attached to or wrapping around the wire, and tubelike conformations with triangular pattern that resemble ideal boron nanotubes. The classification of the transitions is performed by microcanonical inflection-point analysis.

Enhanced Stability of Carbon Doped Boron Nanotubes: An ab-initio Approach

We have performed ab-initio calculations for investigating structural stability of carbon doped boron nanotubes. The considered structures are Armchair (3,3), Zigzag (5,0), and Chiral (4,2) nanotubes consists of 12,20,and 56 atoms respectively. The ground state energies of relaxed nanotubes are calculated, thereby cohesive energy and formation energy. The cohesive energy is increased to a significant extent after carbon doping. Thus, carbon doped boron nanotubes are energetically more stable than pristine nanotubes. The enhancement of energetic stability is also supported by formation energy. It is found that the formation energy is higher for the higher stable structure in all the three nanotubes. It is also observed that carbon doped zigzag nanotube is most favourable nanotube among all the three considered nanotubes because of high formation energy.

Integrable Nonlinear Schrödinger System on a Triangular-Lattice Ribbon

An integrable nonlinear Schrodinger system on a triangular-lattice ribbon, whose geometric configuration is similar to that of \((1,1)\) armchair boron nanotube, is studied in detail. The system Hamiltonian formulation is shown to underline an essentially nontrivial Poisson structure associated with four basic field variables appearing as nearly amplitudes of the probability to find the lattice sites being excited and with two concomitant field variables maintaining the finite background. The coupling parameters of the system are allowed to be complex-valued ones thus permitting to model external magnetic fluxes threading the elementary plackets of a lattice in terms of Peierls phases. An alternative version of zero-curvature representation given in terms of 2 × 2 auxiliary spectral and evolution matrices is proved to support the constructive integrability of the system by means of Darboux–Backlund dressing method. In the framework of Darboux approach the one-soliton solution is found explicitly and analy...

Synthesis of Boron Nanowires, Nanotubes, and Nanosheets

The synthesis of boron nanowires, nanotubes, and nanosheets using a thermal vapor deposition process is reported. This work confirms previous research and provides a new method capable of synthesizing boron nanomaterials. The materials were made by using various combinations of MgB2, Mg(BH4)2, MCM‐41, NiB, and Fe wire. Unlike previously reported methods, a nanoparticle catalyst and a silicate substrate are not required for synthesis. Two types of boron nanowires, boron nanotubes, and boron nanosheets were made. Their morphology and chemical composition were determined through the use of scanning electron microscopy, transmission electron microscopy, and electron energy loss spectroscopy. These boron‐based materials have potential for electronic and hydrogen storage applications.

Nanomaterials for boron and gadolinium neutron capture therapy for cancer treatment

Abstract Cancer is one of the leading causes of death; with it may different types, it kills thousands of people every day. Various types of treatment have been developed to treat and cure cancer. Nanotechnology has emerged as one of the most fruitful areas of science in cancer treatment and the nanomaterials are considered as a medical boon for the diagnosis, treatment and prevention of cancer. The major approaches of nanotechnology in tumor treatment include the development of nanoparticles with less or no tissue-resistance, their biocompatibility, ability as nanocarriers for drug delivery, and enhanced energy deposition in tissue with or without the external influence of microwave, light, magnet, etc. This review presents some of the recent developments in the use of nanoparticles as adjuncts to boron and gadolinium containing compounds in boron neutron capture therapy (BNCT) and gadolinium neutron capture therapy (GdNCT) along with the latest developments in the area of boron nanotubes (BNTs), gadolinium oxide, boron nitride nanotubes (BNNTs) and the boron agent itself.

Tuning the First Hyperpolarizabilities of Boron Nitride Nanotubes

Various carbon-substituted boron nitride (8,0) and (4,4) nanotubes are designed for application as nonlinear optical materials. The structure and first (static and frequency-dependent) hyperpolarizabilities of these boron nitride nanotubes are predicted. The substitution of carbon in the boron nitride nanotube clip significantly enhances the first hyperpolarizabilities by up to several orders of magnitude. The doping pattern of the carbon circle and π electron conjugation are crucial in determining the large first hyperpolarizabilities of these nanotubes.

Study of Properties on Different BnNn Nano Structures in Point of Theoretical Calculations

In this work, we have investigated the structural and electronic properties of BN structures by bending a BN graphitic sheet. This study is based on the tubes generated with the single-walled boron nanotube (SWBNNT) from kind MWNT = 1, as an armchair nanotubes (n, m) with chirality (n = m = 2, 3, 4, 5, 6). Understanding the physical and electronic properties of BN structures requires a meaningful discussion about the theoretical calculation to specify the material properties. This article reviews several investigations regarding BN structures that would be constructed entirely of BN pairs to reveal their properties.

Boron-double-ring sheet, fullerene, and nanotubes: potential hydrogen storage materials.

Similar to carbon-based graphene, fullerenes and carbon nanotubes, boron atoms can form sheets, fullerenes, and nanotubes. Here we investigate several of these novel boron structures all based on the boron double ring within the framework of density functional theory. The boron sheet is found to be metallic and flat in its ground state. The spherical boron cage containing 180 atoms is also stable and has I symmetry. Stable nanotubes are obtained by rolling up the boron sheet, and all are metallic. The hydrogen storage capacity of boron nanostructures is also explored, and it is found that Li-decorated boron sheets and nanotubes are potential candidates for hydrogen storage. For Li-decorated boron sheets, each Li atom can adsorb a maximum of 4 H2 molecules with g(d) =7.892 wt %. The hydrogen gravimetric density increases to g(d) =12.309 wt % for the Li-decorated (0,6) boron nanotube.