Christian Liebscher has held the professorship for Advanced Transmission Electron Microscopy at Ruhr University Bochum since April 2024. The newly established professorship is not only part of the Research Centre Future Energy Materials and Systems, but is based at the Faculty of Physics and Astronomy. Liebscher previously conducted research at the University of California, Berkeley, and has been a research group leader at the Max Planck Institute for Iron Research (MPIE) in Düsseldorf since 2015. Liebscher's professorship will play a central role within the RC FEMS in linking the functional properties of energy materials with their structural and atomic composition. This fundamental understanding is seen as a prerequisite for developing and customising new types of materials.

Website

https://www.atem.ruhr-uni-bochum.de

Hydrogen Storage Materials APT

My research focuses on developing sustainable and recyclable TiFe-based materials for efficient and safe hydrogen storage in stationary applications. By utilizing secondary raw material sources, the project aims to reduce costs and ensure an environmentally friendly hydrogen storage solution. A key challenge is understanding how alloying and impurity elements affect the microstructural stability and hydrogenation properties of TiFe alloys.

My task is to systematically analyze the microstructure down to the atomic level to uncover fundamental mechanisms governing hydrogen uptake and release. By employing atom probe tomography (APT), we quantify the relationship between defect structures, segregation effects, and hydrogen interaction, through an innovative correlative characterization approach, from the millimeter to the nanometer range. Through this research, I aim to provide critical insights into the fundamental material properties required for sustainable hydrogen storage solutions.

My research focuses on the structural characterization of materials across multiple length scales using aberration-corrected (scanning) transmission electron microscopy. I am also particularly interested in understanding the dynamic behavior of these materials under external stimuli—such as temperature, electric fields, and mechanical strain—using in situ TEM techniques. Additionally, advanced methods like 4D-STEM and ptychography play a significant role in my work, enabling high-resolution imaging and quantitative analysis of complex material structures.

My research aims to understand strongly correlated and functional materials—especially quantum materials—at the atomic scale, with the ultimate goal of enabling their tailored design. To achieve this, I employ advanced quantitative high-resolution scanning transmission electron microscopy (STEM), including techniques such as 4D-STEM, ptychography, and spectroscopy, to gain a comprehensive view of material properties. For strongly correlated materials, it is essential to probe not only the atomic structure but also charge, spin, and orbital degrees of freedom at the atomic level; therefore, a significant part of my work involves developing new methods to measure these properties. My research also emphasizes in-situ experiments, where I apply various external stimuli to observe phase transitions and investigate functional materials under real operating conditions. A key objective is to access and understand the transport properties of these materials at local scale.

In situ electron microscopy

Often, the interpretation of processes which govern material behavior is challenging, as materials are normally investigated in a static state, at ambient conditions (i.e. ex situ). Frequently, materials undergo complex transformations which are difficult to understand when only observing the pre and post-states, or, in other cases, relevant material structures and behaviors only appear upon changing of material conditions. As a result, in situ analyses are critical to enable a fundamental understanding of material behaviors. In our work, we utilize highly specialized in situ holders which allow for precise control of sample conditions while imaging at atomic resolution. The instrumentation at the chair of Advanced Transmission Electron Microscopy allows for cooling (from ≤-160 °C to room temperature), heating (up to 1300 °C), and simultaneous bias application.

A variety of in situ experiments are planned and/or ongoing in the group. Among the focus areas are: the study of the evolution of catalyst materials at high temperature and under external biases, the investigation of low temperature phase changes in materials for information technology, the study of room temperature ferroelectric and electromechanical behavior in oxides, and the exploration of grain boundary phase transformations in energy materials.

Hydrogen (H₂) stands out as a promising energy carrier for achieving a CO₂-neutral economy. However, one of the key challenges in establishing a large-scale hydrogen economy is the efficient storage of H₂. Among the various storage methods, solid-state hydrogen storage using metal hydrides offers several advantages over liquid and gas storage, including higher energy density, reduced explosion risk, minimal H₂ loss rates, and the potential for hydrogen purification.

Iron-titanium (FeTi) alloys are particularly attractive for stationary hydrogen storage applications due to their ability to reversibly transform between FeTi and FeTiHx hydride phases under near-room temperature and pressure conditions. Utilizing recycled source materials can help lower production costs and support large-scale FeTi manufacturing. However, the incorporation of recycled materials may introduce additional elements that influence storage capacity and long-term cyclability. Gaining a deeper understanding of the effects of micro-/nanostructure and impurities in FeTi is crucial for optimizing material performance and facilitating the widespread adoption of solid-state hydrogen storage technologies.

Advanced characterization techniques such as transmission electron microscopy (TEM) and atom probe tomography (APT) provide valuable insights into the structural evolution, phase transformations, and microstructural modifications of FeTi during hydrogenation and dehydrogenation cycles. High-resolution scanning transmission electron microscopy (HRSTEM) enables precise identification of phase transitions, while energy-dispersive X-ray spectroscopy (EDS), electron energy loss spectroscopy (EELS), and APT allow for detailed elemental mapping. In this project, these techniques are employed to assess the impact of the microstructure on both high-purity FeTi alloys and FeTi alloys derived from recycled Fe sources. By investigating the evolution of microstructure following hydrogenation cycles, we study the role of impurities originating from recycled materials. These findings contribute to the advancement of FeTi-based materials for efficient, reversible, and scalable hydrogen storage applications. 

In my doctoral work, I contributed to the development of deep learning methods for restoring superresolution structured illumination microscopy (SR-SIM) images. 

In-situ and 4D-STEM Methods

Chang-Lin’s research focuses on in situ electron microscopy methods and 4D-STEM for the study of microstructural and texture evolution in nanocrystalline materials. His work combines advanced microscopy experiments with data-driven analysis approaches, to enable the efficient analysis and interpretation of large diffraction datasets.

I am the team assistant at the Chair of Advanced Transmission Electron Microscopy and have been dedicated to integrating and establishing all administrative matters since the inception of the chair. I am excited to grow together with the team and grateful for the opportunity to gain insight into the scientific work.

My research focuses on an atomic-scale understanding of novel energy-related materials through the development of advanced 4D-STEM techniques. By collecting diffraction patterns with direct electron detectors across the sample, we gain the ability to explore the emergence of local crystal structures, electric and magnetic fields and to enable novel atomic imaging modalities. Additionally, using fast pixelated detectors, we are able to image highly beam-sensitive materials—such as metal-organic frameworks (MOFs)—down to the atomic scale through ptychographic methods.