Nitride Nanotubes Research Articles

1D Vertical Ferroelectricity in Functionalized Carbon/Boron Nitride Nanotubes

Low‐dimensional ferroelectricity is long sought for post‐Moore nanoscale nonvolatile memory. Although a series of 2D ferroelectrics (FEs) have been experimentally confirmed in recent years, the investigations on 1D FEs are still rare. Stimulated by the experimental synthesis of single‐walled carbon/boron nitride nanotubes endohedrally doped by metal halides, our first‐principles calculations show that they can be the candidates for 1D FEs with switchable polarizations vertical to the tube axis as the inner metal halides form into polar zigzag chains. The polarization can be reversed via the migration of metal ions inside the wall, crossing a small barrier around several meV. Similar 1D vertical ferroelectricity in ternary boron carbonitride hybrid nanotubes that have already been synthesized is also predicted. In comparison, herein, polarization is switched by rolling the whole nanotube, which can be realized by applying just a local electric field induced by a tip due to its structural rigidity, which is long sought but remains challenging in current explorations on either conventional or low‐dimensional FEs.

Simulation and Comparison of Capacitance – Voltage Characteristics for Boron Nitride (BN) and Tungsten Disulfide (WS2) Nanotubes as Gate Dielectrics Based Nano MOS Capacitor

The paper presents the design, simulation, and comparison of capacitance-voltage (CV) characteristics for the boron nitride (BN) nanotubes and tungsten disulfide (WS2) nanotubes as gate dielectrics based MOS capacitor. The stack capacitances, flat band voltage, and threshold voltage of these devices were obtained for varying temperatures between 100 K to 500 K. Materials and methods: The two MOS capacitors structured as Au/BN/nSi and Au/WS2/nSi. These devices are designed and simulated using a multi dielectric energy band diagram tool. The sample size for the two MOS structures have been done and a total of 42 samples collected. The stack capacitances and gate charges for voltage ranging between -5 V to +5V were obtained, tabulated, and plotted.

Comparative study of benznidazole encapsulation in boron nitride and carbon nanotubes: A quantum chemistry study

Quantum chemistry methods were used to study boron nitride and carbon nanotubes as possible carriers of antichagasic benznidazole to improve their water solubility and bioavailability. Structurally, no significant changes were observed in both nanotubes throughout the encapsulation process. For the BNZ@BNNT complex, it was possible to notice short interactions, at 0.215 nm, between the hydrogen atoms of the BNZ and the nitrogen atoms of the BNNT. The binding energy reveals that both nanotubes are capable of encapsulating BNZ in an aqueous medium, with values of �71.79 and �62.68 kcal/mol for the BNZ@BNNT and BNZ@CNT complexes. The enthalpy of solvation indicates that the complexes are soluble in water with values of �32.35 and �28.76 kcal mol�1 for the BNZ@BNNT and BNZ@CNT complexes. Regarding chemical stability, Eg and ? show that BNZ@BNNT has greater stability (Eg/? of 3.35/1.68 eV) than BNZ@CNT (0.16/0.08 eV). Overall, our results demonstrate that BNNT is a better candidate to be used as a carrier of BNZ than CNT due to its greater structural and chemical stability.

Comparative study of benznidazole encapsulation in boron nitride and carbon nanotubes: A quantum chemistry study

Quantum chemistry methods were used to study boron nitride and carbon nanotubes as possible carriers of antichagasic benznidazole to improve their water solubility and bioavailability. Structurally, no significant changes were observed in both nanotubes throughout the encapsulation process. For the BNZ@BNNT complex, it was possible to notice short interactions, at 0.215 nm, between the hydrogen atoms of the BNZ and the nitrogen atoms of the BNNT. The binding energy reveals that both nanotubes are capable of encapsulating BNZ in an aqueous medium, with values of �71.79 and �62.68 kcal/mol for the BNZ@BNNT and BNZ@CNT complexes. The enthalpy of solvation indicates that the complexes are soluble in water with values of �32.35 and �28.76 kcal mol�1 for the BNZ@BNNT and BNZ@CNT complexes. Regarding chemical stability, Eg and ? show that BNZ@BNNT has greater stability (Eg/? of 3.35/1.68 eV) than BNZ@CNT (0.16/0.08 eV). Overall, our results demonstrate that BNNT is a better candidate to be used as a carrier of BNZ than CNT due to its greater structural and chemical stability.

Giant rashba splitting of confined Te chains in nanotubes: the size-, chirality-, and type- effects of nanotubes

Understanding the coupling between one-dimensional (1D) materials and their protective materials is essential for developing nanodevices. Herein, we investigate the effect of the size, chirality, and type of nanotubes [such as carbon/boron nitride nanotubes (CNTs/BNNTs)] on the atomic and electronic structures of confined Te chains using density functional theory. We find that the optimal configurations of the Te chains confined in CNTs/BNNTs depend strongly on the size of the nanotubes but weakly on their chirality and type. Furthermore, the Te@BNNTs exhibit giant Rashba splitting with a Rashba constant of up to 2.65 eV Å, while the Te@CNTs show no splitting. This is mainly due to the large bandgap of the BNNTs, as well as the enhanced symmetry breaking of the Te chains when confined. Our findings provide a basis for the design of nano spin devices through protective materials.

Computational study on encapsulation of 5-fluorouracil drug in nanotubes

<abstract><p>Cancer remains a major health concern worldwide, causing high rates of morbidity and mortality. Although chemotherapy with antitumor drugs is the most common treatment for cancer, certain disadvantages limit its usage, such as the damage caused to healthy cells, side effects, and toxicity. Owing to their geometric and mechanical properties, nanotubes are promising nanocarriers of anticancer drugs. Here, the interaction energies of the encapsulation of an anticancer drug by single-walled nanotubes were calculated through the application of the 6–12 Lennard-Jones function with a continuous approach. In particular, the interaction energies of the 5-fluorouracil drug entering three different nanotubes (carbon, silicon and boron nitride) and the offset equilibria inside the nanotubes were obtained. This study aimed at determining the appropriate type and favorable size of nanotubes that can be used to encapsulate the 5-fluorouracil drug. The results showed that the optimal radii of nanotubes for encapsulating the 5-fluorouracil drug were approximately 6.08, 6.05 and 5.98 Å for carbon, boron nitride and silicon nanotubes, corresponding to -16.55, -18.20 and -17.81 kcal/mol, respectively.</p></abstract>

Thermal Conductivity of Graphitic Carbon Nitride Nanotubes: A Molecular Dynamics Study

Graphitic carbon nitride (g-C3N4) nanotubes are recently gaining increasing interest due to their extraordinary physicochemical properties. In the following, we report on simulations using a method of nonequilibrium molecular dynamics and focus on the thermal conductivity variation of g-C3N4 nanotubes with respect to different temperatures, diameters, and chiral angles. In spite of the variation of diameters and chiral angles, the structure of nanotubes possesses high stability in the temperature range from 200 K to 600 K. Although there is little change of the thermal conductivity per unit arc length for nanotubes with the same diameter at different temperatures, it decreases significantly with increasing diameters at the same temperature. The thermal conductivity at different chiral angles has little to do with how temperature changes. Simulation results show that the vibrational density of states of nanotubes distributed, respectively, at ∼11 THz and ∼32 THz, indicating that heat in nanotubes is mostly carried by phonons with frequencies lower than 10 THz.

Investigation about electrostatic three-wall carbon nanotubes (MWCNT), including doping with BN: a model for the nano capacitor

Three-walled boron & nitride nanotubes are used for a theoretical study of a cylindrical molecular capacitor, including an inner cylinder with a positive charge distribution and an outer cylinder with a negative charge distribution. Due to the semiconductor characteristic and dielectric functionality of SWBNTs, DWBNTs and TW (B&C) NTs can be used as a capacitor. Although the SWBNTs @ SWCNTs behave like Nano cylindrical capacitors, we have shown in this study that a dopant of BN in the inner cylinder reduces the energy gap and yields a better capacitance. The dopant of BN in the outer cylinder results in an inverse charge distribution (outer is positive and inner is negative). Therefore under these circumstances, the term capacitor would be meaningless, thought, the gap and the interaction energy decreases compared to the non-dopant form of those capacitors. Density functional theory (DFT) calculations have performed for the structure and stability of three wall carbon Nano tubes (TW (BN&C) NTs). In this work, it was calculated the geometrical structure, and stability to predict NMR and thermodynamics parameters. A mixing of SWBNNTs @ DWCNTs has been modeled and calculated for the suitable structures to storage the H2 molecules for increasing the dielectric. We have found these kinds of Nano-structures are useful for maximum storages of charges compare to other cylindrical capacitor.

Behavior of H2O molecule in carbon nanotube/boron nitride nanotube heterostructure

We perform total-energy electronic-structure calculations of a water molecule inside a (7, 7) carbon nanotube/boron nitride nanotube (CNT/BNNT) heterojunction. The van der Waals interaction is also considered in this study. We find that the equilibrium distance between the water molecule and the wall of the CNT (BNNT) is ≈ 3.3 Å, and the encapsulation energy is 0.22 eV (0.25 eV). The energy profile along the tube axis exhibits a dramatic change in the vicinity of the heterojunction. A speed change of water flow is expected to occur near the heterojunction. Such information would provide valuable insight in nanostructure design for nanofluidics.

Comparative prediction of binding affinity of Hydroxyurea anti-cancer to boron nitride and carbon nanotubes as smart targeted drug delivery vehicles

In this study, the adsorption of Hydroxyurea (HU) onto the inner and outer surfaces of boron nitride and carbon nanotubes (CNTs) was investigated using the density functional theory calculations and molecular dynamics (MDs) simulations in aqueous solution. The values of the adsorption energy show that HU molecule is preferentially adsorbed inside of boron nitride and CNTs with the molecular axis parallel to the tubes axis, which means that the cavity of nanotubes is favorable for encapsulation of this drug. Also, it was found that the HU/boron nitride nanotube (BNNT) system is more stable than the HU/CNT system. The stability of the complexes of HU/ BNNT attributed to the formation of the intermolecular hydrogen bonds between the H atoms of HU molecule and the N atoms of BNNT, which is confirmed by Bader’s quantum theory of atoms in molecules. The natural bond orbital analysis shows the charge transfers occur from HU molecule to nanotubes in all complexes. Moreover, the adsorption of HU molecule on the surfaces of the nanotubes was investigated by explicit water models. Also, the adsorption behavior of HU on the functionalized boron nitride and CNTs is investigated to design and develop new nanocarriers for biomedical applications. Furthermore, MDs simulations are examined in the presence of one and two drug molecules. The obtained results illustrate that the lowest value of Lennard–Jones (L–J) energy between drug and nanotubes exist in the simulation system with two drug molecules.

Vibration analysis of double-bonded micro sandwich cylindrical shells under multi-physical loadings

In the present study, vibration analysis of double bonded micro sandwich cylindrical shells with saturated porous core and carbon/boron nitride nanotubes (CNT/BNNT) reinforced composite face sheets under multi-physical loadings based on Cooper-Naghdi theory is investigated. The material properties of the micro structure are assumed to be temperature dependent, and each of the micro-tubes is placed on the Pasternak elastic foundations, and mechanical, moisture, thermal, electrical, and magnetic forces are effective on the structural behavior. The distributions of porous materials in three distributions such as non-linear non-symmetric, nonlinear-symmetric, and uniform are considered. The relationship including electro-magneto-hydro-thermo-mechanical loadings based on modified couple stress theory is obtained and moreover the governing equations of motion using the energy method and the Hamilton\'s principle are derived. Also, Navier\'s type solution is also used to solve the governing equations of motion. The effects of various parameters such as material length scale parameter, temperature change, various distributions of nanotube, volume fraction of nanotubes, porosity and Skempton coefficients, and geometric parameters on the natural frequency of double bonded micro sandwich cylindrical shells are investigated. Increasing the porosity and the Skempton coefficients of the core in micro sandwich cylindrical shell lead to increase the natural frequency of the structure. Cylindrical shells and porous materials in the industry of filters and separators, heat exchangers and coolers are widely used and are generally accepted today.

Spin dependent transport in hybrid one dimensional BNC systems

Density functional theory is employed to study the electronic and transport properties of a new class of hybrid BNC nanostructures based on graphene/boron nitride nanoribbons encapsulated by graphene/boron nitride nanotubes. Our results show spin polarized transport for three different cases, depending on the nature of the encapsulated nanoribbon (graphene or hexagonal boron nitride (h-BN)), of its encapsulating nanotube, and on the orientation of the ribbon. Also, band gap opening was observed for the armchair carbon nanotube (CNT) based nanostructures, on which the interaction with the encapsulated nanoribbon breaks the CNT’s sub-lattice symmetry. The electronic transport properties are studied from the standpoint of the Landauer–Büttiker formalism, and the results indicate that the current is spin polarized, which theoretically make these structures suitable candidates for applications as spintronic devices, such as spin valves or spin based detectors.

Fe‐Ni‐Mo Nitride Porous Nanotubes for Full Water Splitting and Zn‐Air Batteries

AbstractHigh‐performance catalysts are required in various energy storage and conversion systems. In this work, hierarchical Ni‐Fe‐Mo trimetal nitride nanotubes (NTs) as highly efficient, low‐cost, robustly stable, multifunctional catalysts through room‐temperature Fe incorporation and subsequent thermal treatment for full water splitting and Zn‐air batteries are fabricated. The two‐electrode electrolyzer assembled from the NTs delivers a current density of 10 mA cm−2 at 1.513 V, outperforming the precious metal IrO2|Pt couple and state‐of‐the‐art bifunctional catalysts. Furthermore, two all‐solid‐state Zn‐air batteries with the hierarchical NT air cathode in series can power 55 red light‐emitting diodes with excellent operation stability, at the same time as the electrolyzer based on the hierarchical NTs.

Theoretical study of interaction of NH2X (X = H, CH3, CH2OCH3, and CH2COOH) molecules with AlN and AlP nanotubes

GRAPHICAL ABSTRACT

Double Walled Gallium–Nitride and Zinc-Oxide Nanotube as a Cylindrical Nano Capacitor

Double Walled Gallium–Nitride and Zinc-Oxide Nanotube as a Cylindrical Nano Capacitor

On the possibility of contact-induced spin polarization in interfaces of armchair nanotubes with transition metal substrates

The interaction between armchair carbon and boron nitride nanotubes (NT) with ferromagnetic transition metal (TM) surfaces, namely, Ni(111) and Co(0001), was studied by means of density functional theory. Different configurations of composite compartments mutual arrangement were considered. Partial densities of states and spin density spatial distribution of optimized structures were investigated. Influence of ferromagnetic substrate on nanotubes’ electronic properties was discussed. The values of spin polarization magnitude at the Fermi level are also presented and confirm the patterns of spin density spatial distribution.

Elastic moduli of boron nitride, aluminium nitride and gallium nitride nanotubes using second generation reactive empirical bond order potential

Purpose – The purpose of this paper is to study elastic properties of III-V nitride nanotubes (NNTs) using second generation (REBO) potential. Design/methodology/approach – In the present research paper elastic properties of BN, AlN and GaN nanotubes have been investigated, using the second generation REBO potential by Brenner and co-workers, which is a bond order potential earlier used for carbon nanostructures successfully. In the present calculation, the same form of potential is used with adjusted parameters for h-BN, h-AlN and h-GaN. In all these cases the authors have considered graphite like network and strongly polar nature of these atoms so electrostatic forces are expected to play an important role in determining elastic properties of these nanotubes. The authors generate the coordinates of nanotubes of different chirality’s and size. Each and every structure thus generated is allowed to relax till the authors obtain minima of energy. The authors then apply the requisite compressions, elongations and twists to the structures and compute the elastic moduli. Young’s Modulus, Shear Modulus and Poisson’s ratio for single-walled armchair and zigzag tubes of different chirality’s and size have been calculated. The computational results show the variation of Young’s Modulus, Poisson’s ratio and Shear Modulus for these NNTs with nanotube diameter. The results have been compared with available data, experimental as well as theoretical. Findings – The authors have calculated bond length, cohesive energy/bond, Strain energy, Young’s Modulus, Shear Modulus and Poisson’s ratio. Originality/value – To the best of the knowledge this work is the first attempt to study elastic properties of III-V NNTs using second generation REBO potential

Effect of hybrid nanofillers on the thermal, mechanical, and physical properties of polypropylene composites

In this study, the effect of single and hybrid nanofillers on the thermal, mechanical, and physical properties of polypropylene composites were carried out. This nanocomposite was compounded using two-roll mill mixing method and the filler content was fixed at 4 vol % loading. The single filler used is synthetic diamond (SD), boron nitride (BN), and carbon nanotube (MWNT). The hybrid system was composed by addition of MWNT into single SD and BN. The prepared samples were characterized by thermal properties, tensile and flexural, and these results were supported by the morphology, void content, and melt flow index values. The result showed that the hybrid composite with combination of BN and SD with MWNT indicate higher thermal conductivity and thermal stability and lower thermal expansion. However, no significant improvements in tensile and flexural strengths were observed due to large formation of agglomeration as being captured by SEM micrographs. Furthermore, the existence of higher percent void content suggests low adhesion and poor compatibility between hybrid filler and matrix. This caused detrimental effect of strength of hybrid composites rather than single filler composites.

Dielectric and thermal properties of epoxy/boron nitride nanotube composites

We report the fabrication of and investigations into the dielectric and thermal properties of epoxy/boron nitride nanotube (BNNT) composites. It was found that BNNT fillers can effectively adjust the dielectric constant of epoxy. Moreover, the thermal conductivity of epoxy was improved by up to 69 % with 5 wt % BNNTs. Our studies indicate that BNNTs are promising nanofillers for polymers, to obtain and control an adjustable dielectric property and improved thermal conductivity.

Vibrations in cylindrical shells with transverse elastic isotropy: Application to III–V nitride nanotubes

The vibrational modes of cylindrical shells with transverse elastic isotropy and arbitrary thickness are calculated in the framework of the elasticity theory and a comparison with the isotropic approach is presented. Cylindrical shells are a good model for nanotubes and here an application for nanotubes of transversely isotropic elastic materials is given. We have obtained the expression for the frequency of the radial breathing mode and it is shown that calculated frequencies coming from that expression compare fairly well with those obtained from different ab initio, force constant model calculations and experimental results. Further, the dispersion relations depend on all the elastic coefficients and therefore they are quite different for nanotubes with hexagonal or wurtzite structure. This demonstrates the need to go beyond the isotropic model to investigate the vibrational spectrum of transversely isotropic elastic material nanotubes and nanowires.