Periodic Reporting for period 4 - MatMech (Live Tapings of Material Formation: Unravelling formation mechanisms in materials chemistry through Multimodal X-ray total scattering studies)
Berichtszeitraum: 2023-08-01 bis 2025-07-31
The development of new functional materials for e.g. batteries or catalysis relies on our understanding of the relation between material structure, properties and synthesis. While the intense focus on ‘materials by design’ have made it possible to predict the properties of many materials given an atomic arrangement, knowing how to synthesize it is a completely different story. Material synthesis methods are to a large degree established by extensive parameter studies based on trial-and-error experiments, which slows down the development of novel materials. Specifically, our knowledge of particle nucleation is lacking, as even non-classical views on nucleation such as the concept of pre-nucleation clusters do not apply an atomistic view of the nucleation process. In the project MatMech, we apply new methods in X-ray total scattering and Pair Distribution Function analysis to follow nucleation processes to establish the framework needed for predictive material synthesis. One of the large challenges in studying nucleation is the limited characterization methods that can give structural information on materials without long-range order. In the project, we use time-resolved X-ray total scattering, which gives new possibilities for following structural changes in a synthesis, all the way from a solution over amorphous intermediates to crystalline materials. However, the analysis of the large amount of X-ray scattering data is an enormous bottleneck in such studies, and the data may not always provide enough information to result in a unique structure solution. We are therefore at the same time developing a new multimodal approach for scattering data analysis including methods from data science and Machine Learningc
Through this project, we have made several important scientific and methodological advances. First, we established that polyoxometalate (POM) structures are indeed involved in hydrothermal synthesis and act as pre-nucleation species. Their presence and configuration at the point of nucleation can determine which binary oxide forms—provided the solvent used stabilizes the POMs. This means that solvent choice plays a crucial role in directing reaction pathways, and we demonstrated that a simple and effective way to control structure formation is by considering how precursor materials behave in different solvents.
Building on this insight, we showed that by controlling the structure of the precursor cluster—particularly through solvent manipulation—we can predict and control which material polymorph forms. This was exemplified in our work on molybdenum oxide, where we successfully synthesized specific crystal structures, nanostructures, and defect densities by selecting targeted synthesis parameters.
Our studies of mixed metal oxides further revealed that dopant incorporation is highly system-dependent. For example, transition metal tungstates require the metal to be integrated into a tungsten-based POM in the precursor state, whereas molybdates do not. In the case of high entropy oxides, we found that synthesis success increases significantly when all constituent metals are incorporated into a single precursor cluster, as this reduces the risk of phase segregation. Given the current strong interest in high entropy materials, we believe our in situ studies offer valuable insights for designing new synthesis strategies.
Finally, we achieved significant methodological progress, particularly in synchrotron-based experimental setups and data analysis. One of our key contributions was the development of automated data analysis methods, which have greatly improved the efficiency and accuracy of interpreting complex datasets in real time.
Building on this insight, we showed that by controlling the structure of the precursor cluster—particularly through solvent manipulation—we can predict and control which material polymorph forms. This was exemplified in our work on molybdenum oxide, where we successfully synthesized specific crystal structures, nanostructures, and defect densities by selecting targeted synthesis parameters.
Our studies of mixed metal oxides further revealed that dopant incorporation is highly system-dependent. For example, transition metal tungstates require the metal to be integrated into a tungsten-based POM in the precursor state, whereas molybdates do not. In the case of high entropy oxides, we found that synthesis success increases significantly when all constituent metals are incorporated into a single precursor cluster, as this reduces the risk of phase segregation. Given the current strong interest in high entropy materials, we believe our in situ studies offer valuable insights for designing new synthesis strategies.
Finally, we achieved significant methodological progress, particularly in synchrotron-based experimental setups and data analysis. One of our key contributions was the development of automated data analysis methods, which have greatly improved the efficiency and accuracy of interpreting complex datasets in real time.
With the project, we have contributed important knowledge to the field of material nucleation, which will aid chemists of the future in the design of new, advanced materials.