Nigel A. Marks
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View article: Influence of screw dislocations on stacking order in graphite
Influence of screw dislocations on stacking order in graphite Open
International audience
View article: Compositional Engineering of Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> MXene-NiMoO<sub>4</sub> Hybrid Nanostructures for Enhanced Electrocatalytic Water Oxidation
Compositional Engineering of Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> MXene-NiMoO<sub>4</sub> Hybrid Nanostructures for Enhanced Electrocatalytic Water Oxidation Open
A critical step in realizing the vision of green hydrogen through water splitting is to design oxygen evolution reaction (OER) catalysts that showcase a good balance of activity and stability. This work reports the compositional tuning of …
View article: Stacking faults along the {111} planes seed pressure-induced phase transformation in single crystal silicon
Stacking faults along the {111} planes seed pressure-induced phase transformation in single crystal silicon Open
We explore the onset of phase transformation, at the nanoscale, in single-crystal diamond-cubic silicon (dc-Si) subjected to pressures of 13 GPa using a diamond anvil cell with a methanol-ethanol pressure medium. Transmission electron micr…
View article: Mechanisms and kinetics of prismatic dislocation loop removal during graphitization
Mechanisms and kinetics of prismatic dislocation loop removal during graphitization Open
Molecular dynamics simulations are used to study the structure and removal of prismatic dislocation loops during graphitization. The carbon models contain a mixture of screw and edge dislocations, and are created by self-assembly at high t…
View article: Comparison of hydrostatic and non-hydrostatic compression of glassy carbon to 80 GPa
Comparison of hydrostatic and non-hydrostatic compression of glassy carbon to 80 GPa Open
Understanding new mechanisms for phase transformation in carbon is of considerable interest. This study investigates on the compression conditions required to create recoverable diamond during room-temperature high-pressure compression of …
View article: Origin of preferred orientation in an isotropic material: High pressure synthesis of <i>bc8</i>-Si
Origin of preferred orientation in an isotropic material: High pressure synthesis of <i>bc8</i>-Si Open
High pressure experiments and ab initio calculations are used to investigate unexpected crystallographic preferred orientation in the bc8 phase of silicon formed under non-hydrostatic conditions. Microstructural characterization in two ort…
View article: Graphite rapidly forms via annihilation of screw dislocations
Graphite rapidly forms via annihilation of screw dislocations Open
Graphite is the thermodynamically stable form of carbon and yet is remarkably difficult to synthesize. We show the annihilation of screw dislocations is critical for graphitization. These dislocations wind through the layers like a spiral …
View article: Topological defects and anisotropic development during pre-graphitization
Topological defects and anisotropic development during pre-graphitization Open
Aligned graphenic fragments of varying size, mimicking those found in carbons carbonized through a mesophase, are found to self-assemble towards structures of varying anisotropy when annealed using molecular dynamics simulations. These mod…
View article: Defining graphenic crystallites in disordered carbon: moving beyond the platelet model
Defining graphenic crystallites in disordered carbon: moving beyond the platelet model Open
We develop a picture of graphenic crystallites within disordered carbons that goes beyond the traditional model of graphitic platelets at random orientation. Using large atomistic models containing one million atoms, we redefine the meanin…
View article: Evolution of Threshold Displacement Energy with Dose Studied by Molecular Dynamics Simulations on Irradiated Graphite Models
Evolution of Threshold Displacement Energy with Dose Studied by Molecular Dynamics Simulations on Irradiated Graphite Models Open
International audience
View article: Graphite forms via annihilation of screw dislocations
Graphite forms via annihilation of screw dislocations Open
Graphite is the thermodynamically stable form of carbon, and yet is remarkably difficult to synthesise. A key step in graphite formation is the removal of defects at high temperature ($>$2300~$^{\circ}$C) that allow graphenic fragments to …
View article: Estimating the Case Fatality Ratio for COVID-19 using a Time-Shifted Distribution Analysis
Estimating the Case Fatality Ratio for COVID-19 using a Time-Shifted Distribution Analysis Open
Estimating the case fatality ratio (CFR) for COVID-19 is an important aspect of public health. However, calculating CFR accurately is problematic early in a novel disease outbreak, due to uncertainties regarding the time course of disease …
View article: The mechanical response of glassy carbon recovered from high pressure
The mechanical response of glassy carbon recovered from high pressure Open
Glassy carbon (GC) is usually considered the prototypical super-elastic material, which can almost fully recover its shape after compression of several gigapascals (GPa). In this work, nanoindentation is used to study the mechanical respon…
View article: Estimating the case fatality ratio for COVID-19 using a time-shifted distribution analysis
Estimating the case fatality ratio for COVID-19 using a time-shifted distribution analysis Open
Estimating the case fatality ratio (CFR) for COVID-19 is an important aspect of public health. However, calculating CFR accurately is problematic early in a novel disease outbreak, due to uncertainties regarding the time course of disease …
View article: Estimating the Case Fatality Ratio for COVID-19 using a Time-Shifted Distribution Analysis
Estimating the Case Fatality Ratio for COVID-19 using a Time-Shifted Distribution Analysis Open
Estimating the case fatality ratio (CFR) for COVID-19 is an important aspect of public health. However, calculating CFR accurately is problematic early in a novel disease outbreak, due to uncertainties regarding the time course of disease …
View article: Evidence for Glass Behavior in Amorphous Carbon
Evidence for Glass Behavior in Amorphous Carbon Open
Amorphous carbons are disordered carbons with densities of circa 1.9–3.1 g/cc and a mixture of sp2 and sp3 hybridization. Using molecular dynamics simulations, we simulate diffusion in amorphous carbons at different densities and temperatu…
View article: Epitaxial Formation of SiC on (100) Diamond
Epitaxial Formation of SiC on (100) Diamond Open
We demonstrate locally the coherent formation of silicon carbide (SiC) on diamond, a rare example of heteroepitaxy with a lattice mismatch that exceeds 20%. High-resolution transmission electron microscopy confirms the quality and atomic s…