Open AccessPressure‐Induced Formation and Mechanical Properties of 2D Diamond Boron Nitride
Author(s) -
Cellini Filippo,
Lavini Francesco,
Chen Elton,
Bongiorno Angelo,
Popovic Filip,
Hartman Ryan L.,
Dingreville Remi,
Riedo Elisa
Publication year - 2021
Publication title -
advanced science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.388
H-Index - 100
ISSN - 2198-3844
DOI - 10.1002/advs.202002541
Subject(s) - boron nitride , materials science , diamond , indentation , metastability , monolayer , raman spectroscopy , phase (matter) , phase transition , molecular dynamics , substrate (aquarium) , nitride , crystal (programming language) , diamond cubic , nanotechnology , composite material , chemical physics , crystallography , layer (electronics) , condensed matter physics , chemistry , computational chemistry , optics , organic chemistry , physics , oceanography , geology , computer science , programming language
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 SiO 2 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 SiO 2 is the same of bare SiO 2 , whereas for two‐ and three‐layer‐thick h‐BN on SiO 2 the stiffness increases of up to 50% compared to bare SiO 2 , 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 sp 2 ‐to‐sp 3 phase transition, explaining the lower stiffness observed in thicker h‐BN.