Computer Simulation of Synthesis of Boron-Nitride Nanostructures

Nanotechnology, 2017

We find a possible channel for direct nanosynthesis of boron-nitride (BN) nanostructures, including growth of BN nanotubes from a mixture of BN diatomic molecules by quantumclassical molecular dynamics simulations. No catalyst or boron nanoparticle is needed for this synthesis, however the conditions for the synthesis of each of the nanostructures, such as temperature and flux of the BN feedstock are identified and are compatible with the conditions in an electric arc at high pressure. We also find that BN nanostructures can be synthetized by feeding a boron nanoparticle by BN diatomic molecules, however if hydrogen rich molecules like NH 3 or HBNH are used as a feedstock, two-dimensional nanoflake stable structures are formed.

Chemical Science, 2018

We performed nanosecond timescale computer simulations of clusterization and agglomeration processes of boron nitride (BN) nanostructures in hot, high pressure gas, starting from eleven different atomic and molecular precursor systems containing boron, nitrogen and hydrogen at various temperatures from 1500 to 6000 K. The synthesized BN nanostructures self-assemble in the form of cages, flakes, and tubes as well as amorphous structures. The simulations facilitate the analysis of chemical dynamics and we are able to predict the optimal conditions concerning temperature and chemical precursor composition for controlling the synthesis process in a high temperature gas volume, at high pressure. We identify the optimal precursor/temperature choices that lead to the nanostructures of highest quality with the highest rate of synthesis, using a novel parameter of the quality of the synthesis (PQS). Two distinct mechanisms of BN nanotube growth were found, neither of them based on the root-growth process. The simulations were performed using quantum-classical molecular dynamics (QCMD) based on the density-functional tight-binding (DFTB) quantum mechanics in conjunction with a divide-andconquer (DC) linear scaling algorithm, as implemented in the DC-DFTB-K code, enabling the study of systems as large as 1300 atoms in canonical NVT ensembles for 1 ns time.

2011

2021

We performed integrated modelling of the chemical pathways of formation for boron nitride nanotube (BNNT) precursors during high-temperature synthesis in a B/N2 mixture. Integrated modelling includes quantum chemistry, Quantum–classical molecular dynamics, thermodynamic modelling, and kinetic approaches. We demonstrate that BN compounds are formed via the interaction of molecular nitrogen with small boron clusters, rather than through interactions with less reactive liquid boron. (This process can also be described as N2 molecule fixation.) Liquid boron evaporates to produce these boron clusters (B m with m ≤ 5), which are subsequently converted into B m N n chains. The production of such chains is crucial to the growth of BNNTs because these chains form the building blocks of bigger and longer BN chains and rings, which are in turn the building blocks of fullborenes and BNNTs. Additionally, kinetic modelling revealed that B4N4 and B5N4 species in particular play a major role in the...

Editörün Notu Bu kitapta yer alan bölümlede kullanılan kaynakların, görüşlerin, bulguların, sonuçların, tablo, şekil, resim ve her türlü içeriğin sorumluluğu yazar veya yazarlara aittir. Ayrıca ulusal ve uluslararası telif haklarına konu olabilecek mali ve hukuki sorumluluk ta yazarlara aittir.

KİTAP, 2022

Editörün Notu Bu kitapta yer alan bölümlede kullanılan kaynakların, görüşlerin, bulguların, sonuçların, tablo, şekil, resim ve her türlü içeriğin sorumluluğu yazar veya yazarlara aittir. Ayrıca ulusal ve uluslararası telif haklarına konu olabilecek mali ve hukuki sorumluluk ta yazarlara aittir.

Advanced Materials, 2012

Recent research progress in nanostructured carbon has built upon and yet advanced far from the studies of more conventional carbon forms such as diamond, graphite, and perhaps coals. To some extent, the great attention to nano-carbons has been ignited by the discovery of the structurally least obvious, counterintuitive, small strained fullerene cages. Carbon nanotubes, discovered soon thereafter, and recently, the great interest in graphene, ignited by its extraordinary physics, are all interconnected in a blend of crossfertilizing fi elds. Here we review the theoretical and computational models development in our group at Rice University, towards understanding the key structures and behaviors in the immense diversity of carbon allotropes. Our particular emphasis is on the role of certain transcending concepts (like elastic instabilities, dislocations, edges, etc.) which serve so well across the scales and for chemically various compositions.

Materials science & engineering. C, Materials for biological applications, 2018

The present work reports the adsorption of serine in the neutral and zwitterionic forms on the pure and Pt-decorated BN fullerenes by means of density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations. The binding energy of serine over the fullerene has been studied through its hydroxyl (-OH), carboxyl (-COOH), and amine (-NH) functional groups. Based on our analysis, the binding energy of serine in zwitterionic form (F: -1.52 eV) on BN fullerene is less stable than that of the neutral form (C: -1.61 eV) using the M06-2X functional. Our results indicated that the most stable chemisorption state for serine is through its amine group (I: -2.49 eV) interacting with the Pt-decorated BN fullerene in comparison with the carbonyl group (J: -1.92 eV). The conductivity of the BN and Pt-decorated BN fullerenes is influenced by the energy band gap variation when serine is adsorbed upon the outer surface of fullerenes. Understanding the adsorption of ser...

Reviews of Modern Physics, 2010

Carbon nanotubes undoubtedly take a leading position in nanotechnology research owing to their well-known outstanding structural and electronic properties. Inspired by this, hybrid and functionalized tubular structures have been constructed via several modification paths that involve the presence of molecules, generation of defects, and partial or full replacement of the carbon atoms, always maintaining a nanotube structure. The possibilities are countless. However, this review is mainly dedicated to giving a fundamental insight into the concepts behind wall modification, doping, and formation of a carbon nanotube structure. Theoretical concepts and experimental achievements ranging from carbon nanotubes with low B or N doping to the new physics behind boron nitride nanotubes are covered. Furthermore, special attention is devoted to the bulk and local characterization tools employed with these materials, their suitability and limitations. The theoretical approaches to describing the physical and chemical properties of heteronanotubes are objectively analyzed versus the materials available at this moment.

Computations based on density functional theory (DFT) were performed to get insights into the structural stability, electronic, and magnetic properties of fullerene-like boron nitride cages (f-like BNCs) for different B x N y chemical stoichiometry (x + y = 28). The results reveal at least metastable nanostructures for anionic charge (Q = −1) and doublet state (M = 2); furthermore, a magnetic moment of 1.0 bohr magneton is associated with them. These systems, in general, have high chemical stability due to their large values of cohesion energy, and the structural stability was corroborated by means of vibrational calculations. According to quantum descriptors, they exhibit high polarity (except to B 27 N and B 28 systems), low average chemical reactivity and average work function, and electronic behavior like semiconductors. Therefore, the properties of these systems are improved compared to the B 28 system, and thus the nonstoichiometry fullerenes can be used for more applications than the pristine one.