Cardiff University, School of Chemistry, Materials Discovery Group, UK
报告人简介：Prof. Stefano Leoni obtained his PhD from ETH Zürich with a thesis on periodic surfaces, working with Reinhard Nesper. In 2000 he joined the Max Planck Institute for Chemical Physics of Solids in Dresden as a postdoctoral associate, followed by an Advanced Research Fellowship of the Swiss National Science Foundation. In 2009 he received the VeniaLegendi for inorganic chemistry at Dresden University of Technology, where from 2010 he was lecturer and leader of an externally founded research group. In 2013 he received an Heisenberg Stipendium of the DFG. From 2013 to 2016 he was Adjunct Professor at the University of Berne. He is currently Associate Professor in computational and inorganic chemistry at the University of Cardiff UK, and .s Visiting Professor at Xiamen University. His interests span the broad field of computational material sciences.
报告摘要: Research on novel carbon allotropes never loses momentum. This is due to its ability to form tetrahedral sp3 compounds like diamond, as well as planar sp2 graphite. Between those, manifold intermediates are known, from fullerenes to nanotubes, from hyperbolic Schwarzites to carbon foams. While the planar sp2 unit implies layers of merged six-rings, as regular triangles tile the Euclidean plane, this is not necessarily true for structures based on sp3 centers. Diamond consists of adamantane-like cages of fused six-rings in chair conformation. On the other hand 3D structures with planar six-rings and tetrahedral centers seem to be intrinsically a problem, unless there is a certain amount of odd rings in the structure. Combination of odd and even rings is key to hard and transparent carbon materials, while entangling 1D nanotubes in regular pattern produces superior hydrogen storage materials. Dirac fermions appears in single sheet graphene, while electronic properties can be further tuned in few-layers gaphite. In the attempt to expand the catalogue of carbons, we have found novel graphenoid structures, based on sp2 centers, which nonetheless are not planar, i.e. they represent 3D gaphenes. They define a novel class of compounds, very poorly investigated so far, that can be derived from generalized graphite compounds. Along this way, different graphite(s) as well as graphenoid carbons can be obtained, which hosts interesting electronic properties. The chirality of some of them may represent the starting point towards pure carbon 3D Weyl fermion materials, which so far could be realized in exotic materials only. The possibility of experimentally accessing these materials from suitable precursors can be studied by accurate mechanistic investigation based on advanced molecular dynamics techniques, showing details of pressure-induced material formation.
D. Selli et al, PRB 84, 161411 (2011) ; S.E. Boulfelfel, Scintific Reports 2, 471 (2012); L. Craco, PRB 91, 205120 (2015); L. Craco, PRB 94, 165168 (2016).