Possible mechanism of BN fullerene formation from a boron cluster: Density‐functional tight‐binding molecular dynamics simulations

Abstract

We simulate the formation of a BN fullerene from an amorphous B cluster at 2000 K by quantum mechanical molecular dynamics based on the density-functional tight-binding method. We run 30 trajectories 200 ps in length, where N atoms are supplied around the target cluster, which is initially an amorphous B36 cluster. Most of the incident N atoms are promptly incorporated into the target cluster to form B-N-B bridges or NB3 pyramidal local substructures. BN fullerene formation is initiated by alternating BN ring condensation. Spontaneous atomic rearrangement and N2 dissociation lead to the construction of an sp(2) single-shelled structure, during which the BN cluster undergoes a transition from a liquid-like to a solid-like state. Continual atomic rearrangement and sporadic N2 dissociation decrease the number of defective rings in the BN cluster and increase the number of six-membered rings, forming a more regular shell structure. The number of four-membered rings tends to remain constant, and contributes to more ordered isolated-tetragon-rule ring placement.

Adsorption of NO2, HCN, HCHO and CO on pristine and amine functionalized boron nitride nanotubes by self-consistent charge density functional tight-binding method

“…The SCC-DFTB can also include reliable description of dispersions and weak interactions (Van der Waals and H-bonding) that are important roles for investigation of gas adsorption on a sensing material which is consistent with experimental observations [40,45,47,48]. Moreover, the SCC-DFTB was proved to be effective in the simulation studies of boron nitride nanostructures systems [49][50][51].…”

A path for synthesis of boron-nitride nanostructures in volume of arc plasma

“…The mechanism by which N atoms are incorporated into the B compounds to form alternant BN bond superstructures, which develops under high temperature conditions, has not been analyzed at all until recent theoretical work of Ohta [16], inspired by the experiments of Oku et al [17,18]. Ohta applied quantum-classical molecular dynamics (QCMDs), to successfully build BN nanocages bombarding a small boron cluster, B 36 , with nitrogen atoms each 4 ps, and treating the whole system as a canonical (NVT) ensemble at temperature of 2000 K. After 50 hits of N, the whole system self-organized into a nanocage, with dominant hexagon structure, using all boron atoms for BN bonds.…”

Modification of boron nitride nanocages by titanium doping results unexpectedly in exohedral complexes

“…12. At typical temperature range (1500-2500 K) for producing BN nanocages 32,33 , isomer Ti & 4 with a heptagonal ring is the most abundant product, followed by Ti & 3. Despite being the lowest energy isomer at 0 K, Ti & 2 is only the third major product at synthesis temperatures up to~2400 K. Beyond that temperature, other relatively higher energy isomers (especially Ti & 7) become more competitive.…”

“…Ti@(BN) n , ΔG c , defined by Eq. (1) in the text, at 1500, 2000, and 2500 K (indicated in blue, black, and red, respectively), the typical temperatures for producing BN nanocages 32,33 . Solid circles and empty diamonds represent, respectively, the exohedral and endohedral complexes.…”

“…As strongly contrasted with carbon fullerenes, it is highly exergonic for a BN cage to attach a Ti atom from outside, whereas encaging it is totally hindered from a thermodynamic point of view. This suggests that exohedral Ti(BN) n complexes can most likely be produced by high-temperature synthesis 32,33 like arcmelting, where global minimum structures on the free energy surface are usually formed. Furthermore, changes in cage structure take place upon doping with a single Ti atom, even more drastic than the case of carbon fullerenes.…”