PhD student at FZJ – high-res. time-resolved microstructural evolution under ion irradiation via TEM

Thesis subject: High-Resolution Time-Resolved Microstructural Evolution Under Ion Irradiation.

In situ transmission electron microscopy (TEM) is a powerful characterization technique that can be used to provide a comprehensive understanding of microstructure-property relationships in materials systems in the presence of different stimuli close to operational conditions. Such knowledge is crucial for designing advanced materials with optimized physical and mechanical properties, in particular for energy-related (e.g., solar cell), aerospace and nuclear applications, where materials are exposed to ion irradiation.

Although the effects of ion irradiation have been widely studied by comparing microstructures before and after exposure and as a function of irradiation dose and temperature over timescales of up to years, real-time observations of material evolution during ion interactions remain largely unexplored. Such knowledge is crucial to understand transient processes and defect dynamics, in order to design next-generation materials and devices.

This PhD project will leverage Dynamic TEM (DTEM) to directly visualize irreversible microstructural changes in materials in real time, capturing transformations on timescales ranging from nanoseconds to microseconds with near-atomic spatial resolution. The project will pioneer the direct observation of high-energy ion-induced atomic displacement cascades and the associated ultrafast atomic rearrangements. It will allow progress in the prediction and, eventually, mitigation of their detrimental effect in materials. In addition, it will provide a better understanding of the fundamentals of fast transitions that are able to enhance the glass transition, recrystallization and rejuvenation in amorphous metals. The experiments will reproduce real-world working conditions as closely as possible by integrating temperature, atmosphere, humidity and laser (white light or infrared) illumination. The ion irradiation process will be controlled by tuning parameters such as ion isotope, energy, flux and flow. The key focus areas include:

• Displacement cascade evolution
• Tracking microstructural evolution and defect dynamics.
• Investigating phase transitions under irradiation.

Simulations of displacement-cascade formation and microstructural evolution by molecular dynamic, kinetic Monte Carlo, and kinetic rate theory calculations will complement the experimental findings, in order to provide an improved understanding of the observed phenomena. Advanced image processing techniques will also be applied to analyse low-dose recorded images. Beyond ion irradiation, the project will explore how laser illumination and mechanical forces can influence microstructural stability.

The Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C) at Forschungszentrum Jülich will serve as the host institute in collaboration with ETH Zurich. ER-C is home to a world-class collection of state-of-the-art electron microscopes, enabling high-resolution studies of materials and devices with exceptional spatial, energy, and time resolution.

This project is carried out in collaboration with the Laboratory of Metal Physics and Technology (LMPT), part of the Department of Materials at ETH Zurich, with experts in radiation damage processes and fast phase transitions in materials. Extended research stays at ETH Zurich will provide access to complementary expertise and metallic sample preparation, as well as additional advanced microscopy instrumentation at the microscopy center (ScopeM) of ETH Zurich.

Further information can be obtained from Dr. Amir H. Tavabi, email: a.tavabi@fz-juelich.de and Dr. Robin E. Schäublin, email: robin.schaeublin@mat.ethz.ch