Ultra-high frame rate direct electron 4D-STEM detector

• Subject Area: Materials Science
• Term: Funded in 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 560252986

The advent of four-dimensional scanning transmission electron microscopy (4D-STEM) has opened new approaches and possibilities to study materials from a mesoscopic level down to the atomic scale. Emerging direct electron detectors allow to capture thousands of diffraction patterns per second while scanning a convergent electron beam over the sample and thus 4D- STEM has the potential to replace conventional STEM imaging with annular detectors. This enables to design post-acquisition virtual imaging modalities, to determine local electric or magnetic fields and image light elements at atomic resolution. The ultra-high frame rate direct electron 4D-STEM detector will be used within four research topics: I) Rapid phase, crystal orientation and magnetic domain mapping in nanomaterials, II) 3D phase, crystal orientation and magnetic domain imaging by 4D-STEM tomography, III) In situ 4D-STEM and IV) Light element imaging at atomic resolution by differential phase contrast STEM and electron ptychography. Nanoprobe 4D-STEM experiments with a near parallel electron beam provide rich information of local crystal orientation, strain inside a material or the evolution of magnetic domains. The ultra-high frame rate 4D-STEM detector will enable to determine the structure of nanostruc- tured metals, nanocrystalline catalyst materials and nano hydrides with high sensitivity and acquisition speeds similar to conventional STEM imaging. This allows to capture larger fields of views and facilitates to reduce the electron dose deposited into the material. Novel machine learning based data analysis approaches will be developed to automatically segment, classify and label features within the 4D datasets. The high read out speed of the detector further enables to perform tomographic 4D-STEM experiments to determine the 3D orientation of nanocrystals alongside the 3D evolution of interfaces in nanostructured materials. This approach will be extended to imaging of the 3D structure of magnetic domains by implementing Lorentz-4D-STEM tomography experiments. The ultra-high frame rates the detector offers will further be used to perform dynamic in situ 4D-STEM experiments to probe the phase and domain evolution in materials when exposing them to varying temper- atures and magnetic fields. Differential phase contrast imaging and electron ptychography will provide insights into the atomic structure of complex oxide materials including possible oxygen octahedral tilting and will resolve the distribution of light elements at grain boundaries. Low-dose 4D-STEM will be used to determine the distribution of organic layers surrounding catalytic nanoparticles and aims to resolve the structure of beam sensitive metal organic frameworks.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: 4D-STEM Direkt-Elektronendetektor mit ultra-hoher Bildrate
• Instrumentation Group: 5140 Hilfsgeräte und Zubehör für Elektronenmikroskope
• Applicant Institution: Ruhr-Universität Bochum
• Leader: Professor Dr. Christian Liebscher