The pressing need to minimize our reliance on fossil fuels while at the same time meeting the rapidly growing energy demand has stimulated worldwide efforts to study advanced fission energy.

Developing materials for nuclear reactors that can withstand radiation damage presents a significant, longstanding challenge. Understanding radiation damage and how it affects the properties of useful materials is of principal importance in selecting proper structural materials for the advanced reactors.

To create innovative materials capable of enhanced radiation resistance, it is imperative to understand the damaging effects of radiation on material health. This involves studying these effects in isolated (as opposed to an ensemble of) microstructural features. This requires testing “small” samples, often with nanometer dimensions and at nanometer resolution.

The Early Career Research Program Award made it possible for us to develop a new nano-fabrication approach to create individual, nano-sized, metallic samples. The dimensions and atomic-level microstructures of these samples can be precisely controlled. We were able to implant helium ions (He+) directly into them.

Leveraging our group’s experience in nanomechanics, this grant fostered new collaborations with national labs. The grant let us add new capabilities in our in-situ nanomechanical instrument. That improvement allowed us to uncover new mechanisms in He-induced embrittlement of materials.

DOE’s Early Career award played a pivotal role in the early stage of my career. It allowed me to develop novel experimental and computational methods for testing and fabrication methodologies, as well as to uncover new mechanisms of mechanical deformation. Further, it enabled me to take risks in trying new approaches and in hiring a diverse group of young scientists.


Julia Greer is a professor of Materials Science, Mechanics and Medical Engineering at the California Institute of Technology.


The Early Career Research Program provides financial support that is foundational to early career investigators, enabling them to define and direct independent research in areas important to DOE missions. The development of outstanding scientists and research leaders is of paramount importance to the Department of Energy Office of Science. By investing in the next generation of researchers, the Office of Science champions lifelong careers in discovery science.

For more information, please go to the Early Career Research Program.


Investigation of Radiation Damage Tolerance in Interface‐Containing Metallic Nano Structures

The objective of this research is to obtain a fundamental understanding of interfaces in their role as helium sinks in irradiated metallic microstructures. Radiation damage and the associated production of helium in metals lead to degradation of a material's strength during the lifetime of nuclear reactor components. The research will use a suite of nanoscale characterization and testing techniques, as well as computational tools, to isolate and understand the effects of specific tailored interfaces and deformation mechanisms on the degradation of material properties. The elucidation of these mechanisms will give insight into the requirements for advanced materials for current and next‐generation nuclear reactors.


D.Z. Chen, C.Y. Shi, Q. An, Q.S. Zeng, W.L. Mao, W.A. Goddard, III, and J.R. Greer, “Fractal atomic-level percolation in metallic glasses.” Science 349, 1306 (2015). [DOI: 10.1126/science.aab1233]

R. Liontas, X.W. Gu, E. Fu, Y. Wang, N. Li, N.A. Mara, and J.R. Greer, “Effects of helium implantation on the tensile properties and microstructure of Ni73P27 metallic glass nanostructures.” Nano Letters 14, 5176 (2014). [DOI: 10.1021/nl502074d

Q. Guo, P. Landau, P. Hosemann, Y. Wang, and J. R. Greer, “Helium implantation effects on the compressive response of Cu nano-pillars.” Small 9, 691 (2013). [DOI: 10.1002/smll.201201614

DOE Explains… offers straightforward explanations of key words and concepts in fundamental science. It also describes how these concepts apply to the work that the Department of Energy’s Office of Science conducts as it helps the United States excel in research across the scientific spectrum. For more information on nanoscience and DOE’s research in this area, please go to “DOE Explains… Nanoscience.”


Additional profiles of the Early Career Research Program award recipients can be found on the Early Career Program Page.

The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit www.energy.gov/science.