Analysis of defects on BN nano-structures using high-resolution electron microscopy and density-functional calculations

Abstract

Cubic boron nitride (c-BN) nucleation takes place on hexagonal boron nitride (h-BN) layers growing perpendicular to the substrate surface during thin film synthesis. Studies focused on the nucleation of the cubic phase suggest the possibility that transient phases and/or defects on these h-BN structures have a role in sp3-bonded cubic phase nucleation. In this study, we have investigated the nature, energetics, and structure of several possible defects on BN basal planes, including point defects, 4-, and 5-fold BN rings, that may possibly match the experimentally observed transient phase fine structure. TEM image observations are used to build approximate atomic models for the proposed structures, and DFT calculations are used to relax these structures while minimizing their respective total energies. These optimized atomic geometries are then used to simulate TEM images, which are compared to the experimentally observed structures. Data from DFT calculations and analysis of simulated images from the proposed atomic structures suggest that 4-fold BN rings are more likely to exist on the transient phase possibly leading to c-BN nucleation.

Generating Electric Current Based on the Solvent-Dependent Charging Effects of Defective Boron Nitride Nanosheets

“…The transmission electron microscopy (TEM) image in Figure a shows the sheetlike nanostructure of the as-prepared BN with wrinkles in the center, making it easier to distinguish the presence of sheets and the typical layered compound. The high-resolution TEM image in Figure b displays the interlayer (002) lattice fringe (0.35 nm) of layered BN, which is consistent with the previous reports. , The appearance of some arches (green arrows) and amorphous areas (red circles) demonstrates the existence of some disorders due to the defects and impurities …”

“…18,25 The appearance of some arches (green arrows) and amorphous areas (red circles) demonstrates the existence of some disorders due to the defects and impurities. 26 The X-ray diffraction (XRD) profile of the BNNSs is shown Figure S2 of the Supporting Information. All the peaks can be assigned to those of h-BN (JCPDS Card 45-0896), which strongly agree with those described in the literature.…”

An experimental and theoretical examination of the effect of sulfur on the pyrolytically grown carbon nanotubes from sucrose-based solid state precursors

“…It is well known that capping of CNTs require the presence of non-hexagonal carbon rings following Euler's Law, especially pentagonal ones. In our earlier study dealing with the nano-arch geometry in BN structures, we found that nucle-ation of non-hexagonal rings lead to the formation of highly strained non-planar geometries [36]. Motivated with this, we have investigated several non-hexagonal defect structures and their interaction with sulfur atoms in a planar graphene layer.…”

Ion and electron irradiation-induced effects in nanostructured materials

“…At the same time, very little information relevant to defect production in BN nanostructures under irradiation can be deduced from the experiments on irradiation of bulk hexagonal and cubic BN systems [482][483][484] or thin BN films. 485 Nevertheless, although the data on the response of these nanomaterials to different kinds of irradiation are quite fragmented, in this section, we try to analyze the available experimental and theoretical results and make conclusions on the general behavior of BN nanosystems under impacts of energetic particles.…”