Joke Hadermann

Knowing the crystal structure at unit cell level is crucial for understanding and controlling the physical properties of materials and thus for advancing the various fields of materials science. However, for many materials, the arrangement of the atoms within the unit cell varies over nanoscale domains, especially after reactions or under the influence of external factors. Current techniques, such as three-dimensional electron diffraction, X-ray diffraction and atomic resolution imaging techniques, cannot determine unknown crystal structures for phases that are mixed at nanoscale. Therefore, in REACT, I develop a new method to precisely quantify crystal structures varying at nanoscale, and even unit cell scale, across multiphased particles. The new method will significantly impact materials science by providing, for the first time, the crystal structure of previously unknown phases that occur in functional materials during operation. It will accurately and precisely reveal how their structural parameters - such as chemical bond angles and lengths, and the coordinates and occupancy of atom sites - vary across the particles and change under external influences or reactions. This will give the field of materials science new critical insights into the structural changes accompanying processes like intercalation, degradation and diffusion. To demonstrate its potential, I apply the technique to open questions in materials science: the phases appearing in Li- and Na-ion battery materials during charge-discharge cycling and the changes in the local structure of metal organic frameworks (MOF) during CO2 intercalation. This project will generate a whole new research direction in crystal structure analysis. It will open new doors to understanding material behaviour at the nanoscale, contributing to technological advancements and scientific discoveries across the entire field of materials science.