Simon Billinge

Date: 

Thursday, October 24, 2019, 4:15pm to 5:15pm

Location: 

Pfizer Lecture Hall.
Professor Simon Billinge, Columbia University. "Towards Clusterography, a crystallography for our 21st Century materials."  Woodward CCB Departmental Colloquium.Abstract:

Materials in 21st century applications are increasingly complex,
nano- and meso-structured, heterogeneous and defective. We seek to engineer exactly this complexity to get the high performance that we desire from the materials. Not only that, functional materials generally change their structure when they are functioning, and so studying the structural complexity as a function of time during device operation becomes critical. What hasn't changed in the 21st century is that the properties of the materials derive from their atomic arrangements, and it is therefore crucial to be able to control and characterize atomic arrangements on all the length-scales relevant to the properties in question. Properties depend on bond-length changes on picometer length-scales, which makes the challenge all the more intense.  We have ever improving experimental and theoretical tools to tackle this challenge, and I will describe recent developments in x-ray and neutron scattering to that give us such picometer precision insights into nanoscale structures in both ex-situ and in-situ environments.  A consequence of these developments is that we need to start thinking about structure in a less conventional way. Our understanding is embedded in the language of crystallography and space-groups, or point symmetries relevant to isolated molecules. What we actually have in general is something  in between, something I call clusterography, and we need to start thinking about how properties emerge from these multi-scale systems that are ntermediate.