Speaker: Prof. David A. Keen (University of Oxford)

Title: Local complexity in (mostly) cubic crystals

Date: 6 December 2022

Place: Building 1, meeting room



Cubic crystals have always appealed to condensed matter physicists for their conceptual simplicity and structural richness.  The first crystal structure to be determined by X-ray diffraction was cubic and they still play a key role in diffraction instrumentation today.  But what happens when parts of the structure deviate from cubic symmetry at a local level?  How can we determine this local complexity experimentally and – equally importantly – interpret our data in a crystallographically coherent manner?  This is what this talk will explore. I will outline an analysis methodology based on neutron and X-ray diffraction and pair distribution function methods which can be used to extract local complexity signatures within long-ranged ordered crystals. The talk will include a number of examples including phase transitions in perovskites, simple ice structures and other disordered cubic-structured materials.