Energetic Particle Beams: Radiation Effects and Nanofabrication

ChEMS Seminar

Featuring Jie Lian, Ph.D.
Assistant Research Scientist
Department of Nuclear Engineering and Radiological Sciences
University of Michigan, Ann Arbor

Location:  Engineering Tower 204

Abstract:
Energetic particle beam irradiation represents a well-controlled method to simulate radiation damage of materials as a result of α-decay events of the incorporated actinides. In this talk, the recent progress in understanding ion beam irradiation-induced phenomena in pyrochlore A2B2O7, potential nuclear waste form and advanced fuel matrix for actinide incorporation, will be briefly reviewed, with a focus on the ion beam-induced crystalline-to-amorphous and pyrochlore-to-fluorite structural transitions. Systematic ion irradiation studies of lanthanide pyrochlores with B = Ti, Zr, and Sn have indicated that the radiation response of the pyrochlore compounds is highly dependent on compositional changes. Both the ionic size and cation electronic configurations (e.g., bond-types) affect the structural distortion from the ideal fluorite structure and thus the response of pyrochlore-structure types to ion beam irradiation. These fundamental results provide critical data in understanding the materials’ behavior to radiation damage, and have significant implications for the design and selection of materials for actinide incorporation.

Furthermore, energetic particle beam irradiation provides a very unique tool for processing nanostructures of various types which may lead to important technological applications. Numerous novel nanostructures have been created by ion beam techniques in pyrochlore structured materials including amorphous and disordered nano-domains, perfectly lattice matched two-dimensional nanolayers, self-organized ripple structures, metallic nanoparticles, and nanowires. Different mechanisms are involved in the formation of nanostructures including ion beam-induced amorphization, order-disorder structural transition and phase decomposition. Combining with ‘top-down’ fabrication methods, the potential application of energetic beam irradiation on the controlled fabrication of ordered nanostructures will be demonstrated.

About the Speaker:
Jie Lian, Ph.D., joined in the Ph.D. program in the Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, in 1998, and became a member of the radiation effects research group, led by Professors Rodney C. Ewing and Lumin Wang. He received his Ph.D. degree in Nuclear Engineering and Radiological Sciences from the University of Michigan in 2003. After a two year post-doctoral research post, he is now an assistant research scientist in a research group that includes faculty and students from three departments:  Nuclear Engineering and Radiological Sciences, Materials Science and Engineering, and Geological Sciences. In the last nine years, he has been working on interdisciplinary research projects involving disciplines such as nuclear engineering, geological sciences, and materials science and engineering. His main research interests include radiation effects in nuclear materials, radioactive waste management, ion beam modification of materials, material characterization with advanced transmission electron microscopy, processing and characterization of nanostructured materials.  Lian has authored or co-authored three book chapters and more than 100 research papers (with more than 80 papers in SCI-indexed refereed journals).  Lian has an active collaboration with U.S. scientists in national laboratories, U.S. and foreign universities, and research institutes (e.g., in China, Germany, Russia, Singapore, and the U.K.).