Twists and Turns in Layered Materials

Chris Ewels / Jean Rouxel Institute of Materials in Nantes, University of Nantes, France

September 26, 2024

Online live talk

Introduction

This talk will explore folds and dislocations in layered materials. 2D-layered materials are at the heart of the nanomaterials revolution and while defects dominate their behaviour, research typically focuses on point defects. However, linear defects like folds and dislocations are common and observed in all layered materials.  The intrinsic anisotropy of low dimensional carbon nanoobjects such as graphene opens up possibilities for structural distortion and behavior not available to three-dimensional crystals.  Different dislocation orientation results in families of radically different structure types which exploit the available out-of-plane dimension [1,2].  For example folding creates distinct Raman spectroscopic signatures [3] and can lead to local band gap variation in layered materials such as boron nitride [4]. Folded, rolled, distorted and rippled sheets are interesting, not only in themselves, but also for the void spaces they create. There are a number of ways carbon can be used to confine other materials, either modifying bulk behavior or inducing unique low-dimensional change in the materials they are hosting [5].  Examples we will explore in the talk include the formation of new 1D material phases of intercalants such as phosphorus [6].

Figure 1: (top) Experimental image of phosphorus filled single walled carbon nanotube
(bottom) collapsed carbon nanotube with filling of the edge cavities.

References:
[1] M. Heggie et al. J. Nucl. Mater. 2011, 413, 150, doi: 10.1016/j.jnucmat.2011.04.015.
[2] J. McHugh et al. Carbon 2022, 188, 401, doi: 10.1016/j.carbon.2021.11.072.
[3] E. Picheau et al. ACS Nano 2021, 15, 596, doi: 10.1021/acsnano.0c06048.
[4] A. Impellizzeri et al. J. Phys. Chem. C 2022, 126, 17746, doi: 10.1021/acs.jpcc.2c05549.
[5] D. Rybkovskiy et al. Carbon 2018, 142, 123, doi: 10.1016/j.carbon.2018.10.049.
[6] D. Rybkovskiy et al. ACS Nano 2022, 16, 6002, doi: 10.1021/acsnano.1c11349.
[7] Full publication list available with pdf links from https://chrisewels.github.io/ewels.info/

Chris Ewels

graduated from Oxford University in 1993 in “Metallurgy and the Science of Materials”. After a Ph.D. in 1997 from the University of Exeter UK, for computational studies of oxygen defects in silicon, he moved to Sussex University where he worked on radiation induced defects in graphite and carbon nanosystems. At Sussex he joined the Vega Science Trust with Sir Harry Kroto, where he created an online science TV channel and developed a passion for public communication of science. In Paris he worked at the national aerospace research facilities ONERA, and was then a Marie Curie Individual Research Fellow at the Université Paris Sud within the electron microscopy group of Professor Christian Colliex.  In 2006 he received the European Marie Curie Excellence Award and in the same year jointed the CNRS at the Institute of Materials in Nantes, becoming Directeur de Recherche in 2015.  His work focuses on computer modelling of nanoscale carbons in close collaboration with experimental colleagues. He has authored over 200 journal publications including nine book chapters, and is on the Stanford University list top 2% most cited active scientists.  His interest in science communication continues, with Web videos he has commissioned and produced now viewed over 1.5 million times.  He is now joint head of the Physics of Materials and Nanostructures group at the IMN, coordinates nanocarbon initiatives at the local, regional, national and European level, and is actively building European research networks for both Nantes University (MaterialWell) and the regional CNRS (as DR17 European Science Advisor).