A new X-ray technique developed by Cornell engineers has revealed the cause of a long-identified flaw in sodium-ion batteries; a discovery that could prove to be a major step toward making sodium-ion... Read more about Engineers reveal cause of key sodium-ion battery flaw
Andrej Singer received his Ph.D. degree (2012) in Physics from the University of Hamburg, Germany in the lab of Prof. Edgar Weckert and Prof. Ivan Vartanyants, following a Physics diploma from the University of Muenster, Germany. He studied the properties of new x-ray sources, particularly their ability to generate interference patterns, similar to lasers in optics. He then worked as a Postdoc in the lab of Prof. Oleg Shpyrko at the University of California San Diego. Singer’s group applies coherent x-ray scattering techniques to study a wider range of materials, spanning from fundamental correlated electron materials and applied "real" materials in operando devices to photonic crystals, in particular those present in nature.
Our group uses state-of-the-art x-ray characterization to see inside complex nanomaterials during operation and harness the mesoscale phenomena for advanced functionality. Specifically, we are interested in understanding the fundamental interactions leading to increased electrocatalytic activity and durability of catalysts. We also apply x-ray imaging resonant and non-resonant diffraction to study ion intercalation and ion transport in materials for energy storage. Finally, we induce novel states in quantum materials and interrogate their properties with x-rays at free-electron lasers.
1. Defect dynamics and phase transformations in energy storage materials: Electrochemical energy storage devices, the dominant power source for mobile electronics, are increasingly used in hybrid and fully electric vehicles and are promising candidates for the grid storage. Electrodes with increased capacity, faster charge rates, and minimal capacity fade are required. Our group uses various state-of-the-art x-ray scattering and imaging techniques to study the dynamical processes in nanoparticulate lithium-ion and sodium-ion based positive electrode materials. The in-situ understanding of the ion-motion-induced physical phenomena at the single particle level is key to for advanced functionality.
2. New phases of matter far from equilibrium: The emergence of order through symmetry breaking is a fascinating phenomenon. It leads to a plethora of intriguing ground states found in antiferromagnets, Mott insulators, superconductors, and density wave systems. Exploiting states of matter far from equilibrium provides even more surprising routes to symmetry-lowered, ordered states. Photoexcitation is unique in accessing non-equilibrium dynamics, and our group uses pump-probe techniques at the recently developed x-ray free-electron lasers to study ultrafast processes in strongly correlated electrons systems. We seek to explore new non-equilibrium phases of matter, which have the potential for technological applications.
3. Self-assembly of biological photonic crystals: Light interference, as was realized as early as the beginning of the 19th century by Lord Rayleigh, is a common cause of the bright coloring of various animals such as the spine of the sea mouse, butterfly wings, feathers of birds of paradise, or the skin of chameleons. These photonic crystals are not only interesting for evolutionary biology but also appealing for metamaterial research and exciting applications such as designing Weyl points. Our group uses coherent x-ray imaging and ptychography to study the self-assembly processes underpinning the formation of biological photonic crystals in various species.
Structure of materials, mechanical properties, advanced x-ray characterization, and kinetics of materials
Selected Awards and Honors
- NSF Career Award, 2019
- VFFD award at DESY, Hamburg 2013
- Scholarship from Studienstiftung des deutschen Volkes 2007
- University of Muenster, 2008
- Ph D University of Hamburg, 2012