We report on the growth and formation of single-layer boron nitride dome-shaped nanostructures mediated by small iron clusters located on flakes of hexagonal boron nitride. The nanostructures were synthesized in situ at high temperature inside a transmission electron microscope while the e-beam was blanked (Figure 1). The formation process, typically originating at defective step-edges on the boron nitride support, was investigated using a combination of transmission electron microscopy, electron energy loss spectroscopy and computational modelling. The h-BN dome-shaped nanostructure of Figure 1 was used to simulate images of BN protrusions at various angles relative to the incident electron beam, by adjusting effectively the beam direction. Figures 2 presents simulated images for beam angles of 0° (2a), 30° (2b,c) and 50° (2d), respectively, relative to the h-BN plane normal, in comparison with experimentally observed features (Figures 2e-h). The image simulations are in striking agreement with the experimental images, consistent with the circular features being protrusions formed normal to the h-BN plane, whilst the hemispheres correspond to protrusions tilted with respect to the h-BN plane. Computational modelling showed that the domes exhibit a nanotube-like structure with flat circular caps (Figure 3) and that their stability was comparable to that of a single boron nitride layer.
Nanostructured carbon protrusions have been studied since 2001 [1-3], but the investigation of analogous BN structures has only just begun. In the present study, we have shown that even member rings are required for the formation of h-BN dome-shaped protrusions, but not in the form of active linear defects, containing B-B and N-N bonds, as observed recently in BN monolayers under electron beam irradiation . Furthermore, according to our molecular simulations result the even members rings present in the half dome structure present B-B and N-N bonds (Figure 4). The BN dome-shaped nanostructures represent a new material that perhaps by hosting metal atoms may unveil new optical, magnetic, electronic or catalytic properties, emerging from confinement effects.
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To cite this abstract:A. La Torre, E. H. Åhlgren, M. W. Fay, F. Ben Romdhane, S. T. Skowron, A. J. Davies, C. Parmenter, J. Jouhannaud, A. N. Khlobystov, G. Pourroy, E. Besley, P. D. Brown, F. Banhart; In-situ TEM growth of single-layer boron nitride dome-shaped nanostructures catalysed by iron clusters. The 16th European Microscopy Congress, Lyon, France. https://emc-proceedings.com/abstract/in-situ-tem-growth-of-single-layer-boron-nitride-dome-shaped-nanostructures-catalysed-by-iron-clusters/. Accessed: December 2, 2023
EMC Abstracts - https://emc-proceedings.com/abstract/in-situ-tem-growth-of-single-layer-boron-nitride-dome-shaped-nanostructures-catalysed-by-iron-clusters/