Compression-Induced Modification of Boron Nitride Layers: A Conductive Two-Dimensional BN Compound

Barboza, Ana Paula Moreira; Matos, Matheus J. S.; Chacham, H.; Batista, Ronaldo J. C.; Oliveira, Alan Barros de; Mazzoni, Mário S. C.; Neves, Bernardo R. A.

doi:10.1021/acsnano.8b01911

Cited by 27 publications

(41 citation statements)

References 30 publications

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“…[24]; however, our results differ in terms of values, possibly due to the humid environment in which the experiments in Ref. [24] have been conducted. Since the variation in the local contact potential upon compression can indicate the modification of the lattice structure in 2–3L h‐BN, and the transition to a different crystal phase, we use Raman spectroscopy to investigate the film structure before and after pressurization.…”

Section: Figurecontrasting

confidence: 76%

“…[ 20–22 ] Recent density functional theory (DFT) simulations [ 23 ] have reported on the pressure induced transformation of few‐layer h‐BN into different types of sp 3 BN structures. Other simulations [ 24 ] have shown a pressure induced formation of a conductive structure (called “bonitrol”) when few‐layer h‐BN is in presence of water, and experiments [ 24 ] supported these findings by monitoring the change in work function of few‐layer h‐BN upon local compression in a humid environment. However, so far there has been no direct experimental evidence of a pressure‐induced conversion of atomically thin h‐BN into sp 3 BN structures, and no experiments have investigated the mechanical properties of the pressure induced diamond BN phase.…”

Section: Figurementioning

confidence: 86%

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Pressure‐Induced Formation and Mechanical Properties of 2D Diamond Boron Nitride

et al. 2020

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Understanding phase transformations in 2D materials can unlock unprecedented developments in nanotechnology, since their unique properties can be dramatically modified by external fields that control the phase change. Here, experiments and simulations are used to investigate the mechanical properties of a 2D diamond boron nitride (BN) phase induced by applying local pressure on atomically thin h‐BN on a SiO2 substrate, at room temperature, and without chemical functionalization. Molecular dynamics (MD) simulations show a metastable local rearrangement of the h‐BN atoms into diamond crystal clusters when increasing the indentation pressure. Raman spectroscopy experiments confirm the presence of a pressure‐induced cubic BN phase, and its metastability upon release of pressure. Å‐indentation experiments and simulations show that at pressures of 2–4 GPa, the indentation stiffness of monolayer h‐BN on SiO2 is the same of bare SiO2, whereas for two‐ and three‐layer‐thick h‐BN on SiO2 the stiffness increases of up to 50% compared to bare SiO2, and then it decreases when increasing the number of layers. Up to 4 GPa, the reduced strain in the layers closer to the substrate decreases the probability of the sp2‐to‐sp3 phase transition, explaining the lower stiffness observed in thicker h‐BN.

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Section: Figurecontrasting

confidence: 76%

Section: Figurementioning

confidence: 86%

Pressure‐Induced Formation and Mechanical Properties of 2D Diamond Boron Nitride

et al. 2020

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“…Recent research efforts have focused on the pressure induced formation of new phases in 2D materials. In particular, the formation of an ultrastiff phase, diamene, was found while locally pressurizing epitaxial graphene films [10,11]; other reports have shown the pressure induced formation of an insulating phase from exfoliated graphene flakes in a humid environment [12,13], and more recently the formation of bonitrol from hexagonal boron nitride was demonstrated [14].…”

Section: Introductionmentioning

confidence: 98%

Layer dependence of graphene-diamene phase transition in epitaxial and exfoliated few-layer graphene using machine learning

Cellini¹,

Lavini²,

Berger³

et al. 2019

2D Mater.

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The study of the nanomechanics of graphene -and other 2D materials -has led to the discovery of exciting new properties in 2D crystals, such as their remarkable in-plane stiffness and out of plane flexibility, as well as their unique frictional and wear properties at the nanoscale.Recently, nanomechanics of graphene has generated renovated interest for new findings on the pressure-induced chemical transformation of a few-layer thick epitaxial graphene into a new ultrahard carbon phase, named diamene. In this work, by means of a machine learning technique, we provide a fast and efficient tool for identification of graphene domains (areas with a defined number of layers) in epitaxial and exfoliated films, by combining data from Atomic Force Microscopy (AFM) topography and friction force microscopy (FFM). Through the analysis of the number of graphene layers and detailed Å-indentation experiments, we demonstrate that the formation of ultra-stiff diamene is exclusively found in 1-layer plus buffer layer epitaxial graphene on silicon carbide (SiC) and that an ultra-stiff phase is not observed in neither thicker epitaxial graphene (2-layer or more) nor exfoliated graphene films of any thickness on silicon oxide (SiO2).

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“…Atomic force microscopy (AFM)-based methodologies stand out for their ability to locally map the sample characteristics down to the nanometer scale, and for their operational simplicity and flexibility, which allow numerous characterization and nanomanipulation experiments to be performed in situ on the same sample area, and at the same time [13][14][15]. Among the different AFM techniques, dynamic mode AFM, and in particular AFM phase shift imaging [16][17][18][19], represents a simple technique to achieve thin films nanoscale surface characterization, free of restriction on experimental conditions and operational instrumentations.…”

Section: Introductionmentioning

confidence: 99%

Atomic force microscopy phase imaging of epitaxial graphene films

et al. 2020

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Dynamic mode atomic force microscopy phase imaging is known to produce distinct contrast between graphene areas of different atomic thickness. But the intrinsic complexity of the processes controlling the tip motion and the phase angle shift excludes its use as an independent technique for a quantitative type of analysis. By investigating the relationship between the phase shift, the tip-surface interaction, and the thickness of the epitaxial graphene areas grown on silicon carbide, we shed light on the origin of such phase contrast, and on the complex energy dissipation processes underlying phase imaging. In particular, we study the behavior of phase shift and energy dissipation when imaging the interfacial buffer layer, single-layer, and bilayer graphene regions as a function of the tip-surface separation and the interaction forces. Finally, we compare these results with those obtained on differently-grown quasi free standing single-and bilayer graphene samples.

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Compression-Induced Modification of Boron Nitride Layers: A Conductive Two-Dimensional BN Compound

Cited by 27 publications

References 30 publications

Pressure‐Induced Formation and Mechanical Properties of 2D Diamond Boron Nitride

Pressure‐Induced Formation and Mechanical Properties of 2D Diamond Boron Nitride

Layer dependence of graphene-diamene phase transition in epitaxial and exfoliated few-layer graphene using machine learning

Atomic force microscopy phase imaging of epitaxial graphene films

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