Research visit and lecture of Professor Siegbert Schmid from the University of Sydney
If there are competing interactions or perturbations in a crystalline material – these can be deviations from an ideal chemical composition or concern space problems of the atoms involved –, especially modulations occur as an “answer” of the crystal structure. These are specific changes of individual structure parameters, e.g. displacements of atoms. Such materials are also characterized by sharp X-ray diffraction maxima. Due to the existing disturbances, however, they no longer exhibit a translational periodic arrangement of the atoms in the physical three-dimensional space. These order states are named “modulated structures”. Once considered rare, it is now known that modulated structures do occur in all areas of chemistry from elements to proteins. Currently, 128 incommensurate modulated and 24 composite structures are collected in the Bilbao Incommensurate Structures Database.
During his visit he gave the lecture entitled “Beyond 3D-order: Modulated structures from elements to proteins”. In his lecture Prof. Schmid focused on the fundamental aspects of commensurate and incommensurate modulated structures as well as composite structures. He described structural chemistries on base of examples, predominantly chosen from transition metal oxides. Prof. Schmid, who shortly before participated in the “Lithium Battery Discussions on Electrode Materials” in Arcachon (France), pointed out that with increasing studies of battery materials the researchers will have to deal more often with modulated structures. This is due to the composition changes making batteries work. Up to now, there are examples in which improved battery performance occurs with modulated structures. However, this research area is not yet explored, as Prof. Schmid noticed, and deserves more detailed studies.
Professor Schmid’s research interests lie in the synthesis and structural characterization of aperiodic and other materials with potential technological applications, e.g. insertion materials for rechargeable batteries. In this regard, back to 2017, we established a collaboration, since he synthesized a material which is a high potential candidate as aluminum-ion solid electrolyte. This has been figured out by the IEP in a combined theoretical approach for identifying battery materials. The material will now be electrochemically characterized at the IEP.
Within the joint-research project “R2RBattery”, financially supported by the German Federal Ministry of Education and Research, the IEP is working on high-valent ion batteries, including an aluminum-ion battery.