scholarly journals Topologically protected interface phonons in two-dimensional nanomaterials: hexagonal boron nitride and silicon carbide

Nanoscale ◽  
2018 ◽  
Vol 10 (29) ◽  
pp. 13913-13923 ◽  
Author(s):  
Jin-Wu Jiang ◽  
Bing-Shen Wang ◽  
Harold S. Park

We perform both lattice dynamics analysis and molecular dynamics simulations to demonstrate the existence of topologically protected phonon modes in two-dimensional, monolayer hexagonal boron nitride and silicon carbide sheets.

2021 ◽  
Vol 7 (8) ◽  
pp. eabe7138
Author(s):  
M. Fischer ◽  
J. M. Caridad ◽  
A. Sajid ◽  
S. Ghaderzadeh ◽  
M. Ghorbani-Asl ◽  
...  

Luminescent centers in the two-dimensional material hexagonal boron nitride have the potential to enable quantum applications at room temperature. To be used for applications, it is crucial to generate these centers in a controlled manner and to identify their microscopic nature. Here, we present a method inspired by irradiation engineering with oxygen atoms. We systematically explore the influence of the kinetic energy and the irradiation fluence on the generation of luminescent centers. We find modifications of their density for both parameters, while a fivefold enhancement is observed with increasing fluence. Molecular dynamics simulations clarify the generation mechanism of these centers and their microscopic nature. We infer that VNCB and VB− are the most likely centers formed. Ab initio calculations of their optical properties show excellent agreement with our experiments. Our methodology generates quantum emitters in a controlled manner and provides insights into their microscopic nature.


Nanomaterials ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 1047 ◽  
Author(s):  
Marie Krečmarová ◽  
Daniel Andres-Penares ◽  
Ladislav Fekete ◽  
Petr Ashcheulov ◽  
Alejandro Molina-Sánchez ◽  
...  

The successful integration of few-layer thick hexagonal boron nitride (hBN) into devices based on two-dimensional materials requires fast and non-destructive techniques to quantify their thickness. Optical contrast methods and Raman spectroscopy have been widely used to estimate the thickness of two-dimensional semiconductors and semi-metals. However, they have so far not been applied to two-dimensional insulators. In this work, we demonstrate the ability of optical contrast techniques to estimate the thickness of few-layer hBN on SiO2/Si substrates, which was also measured by atomic force microscopy. Optical contrast of hBN on SiO2/Si substrates exhibits a linear trend with the number of hBN monolayers in the few-layer thickness range. We also used bandpass filters (500–650 nm) to improve the effectiveness of the optical contrast methods for thickness estimations. We also investigated the thickness dependence of the high frequency in-plane E2g phonon mode of atomically thin hBN on SiO2/Si substrates by micro-Raman spectroscopy, which exhibits a weak thickness-dependence attributable to the in-plane vibration character of this mode. Ab initio calculations of the Raman active phonon modes of atomically thin free-standing crystals support these results, even if the substrate can reduce the frequency shift of the E2g phonon mode by reducing the hBN thickness. Therefore, the optical contrast method arises as the most suitable and fast technique to estimate the thickness of hBN nanosheets.


RSC Advances ◽  
2016 ◽  
Vol 6 (56) ◽  
pp. 51205-51210 ◽  
Author(s):  
Matthew Becton ◽  
Xianqiao Wang

Molecular dynamics simulations are performed to investigate the possibility of generating motion from stiffness gradients with no external energy source.


Nanoscale ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 5607-5616 ◽  
Author(s):  
Song Liu ◽  
Jeffrey Comer ◽  
Adri C. T. van Duin ◽  
Diana M. van Duin ◽  
Bin Liu ◽  
...  

An understanding of the nucleation and growth of hexagonal boron nitride (hBN) on nickel substrates is essential to its development as a functional material.


2015 ◽  
Vol 1726 ◽  
Author(s):  
Eric Perim ◽  
Douglas S. Galvao

ABSTRACTNanoscrolls consist of sheets rolled up into a papyrus-like form. Their open ends produce great radial flexibility, which can be exploited for a large variety of applications, from actuators to hydrogen storage. They have been successfully synthesized from different materials, including carbon and boron nitride. In this work we have investigated, through fully atomistic molecular dynamics simulations, the dynamics of scroll formation for a series of graphene-like carbon nitride (CN) two-dimensional systems: g-CN, triazine-based (g-C3N4), and heptazine-based (g-C3N4). Carbon nitride (CN) structures have been attracting great attention since their prediction as super hard materials. Recently, graphene-like carbon nitride (g-CN) structures have been synthesized with distinct stoichiometry and morphologies. By combining these unique CN characteristics with the structural properties inherent to nanoscrolls new nanostructures with very attractive mechanical and electronic properties could be formed. Our results show that stable nanoscrolls can be formed for all of CN structures we have investigated here. As the CN sheets have been already synthesized, these new scrolled structures are perfectly feasible and within our present-day technology.


Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 662
Author(s):  
J. M. Ramirez-de-Arellano ◽  
A. Fransuani Jiménez G. ◽  
L. F. Magaña

We investigated the effect of doping a hexagonal boron nitride surface (hBN) with Ti or Pt on the adsorption of CO2. We performed first-principles molecular dynamics simulations (FPMD) at atmospheric pressure, and 300 K. Pristine hBN shows no interaction with the CO2 molecule. We allowed the Ti and Pt atoms to interact separately, with either a B-vacancy or an N-vacancy. Both Ti and Pt ended chemisorbed on the surface. The system hBN + Ti always chemisorbed the CO2 molecule. This chemisorption happens in two possible ways. One is without dissociation, and in the other, the molecule breaks in CO and O. However, in the case of the Pt atom as dopant, the resulting system repels the CO2 molecule.


Nanoscale ◽  
2020 ◽  
Vol 12 (18) ◽  
pp. 10180-10188
Author(s):  
Yan Chen ◽  
Huasong Qin ◽  
Juzheng Song ◽  
Zeming Liu ◽  
Yilun Liu ◽  
...  

The mechanical and thermal behaviors of three-dimensional hexagonal boron nitride aerogels (hBNAGs) are studied using molecular dynamics simulations based on a binary phase-field crystal (PFC) model.


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