Two Argonne researchers will discuss their Laboratory-Directed Research and Development (LDRD) sponsored work at the LDRD Seminar Series presentation Tuesday, June 11, 2019, at 12:30 p.m. in Building 212, Room A157. All are welcome to attend.
Visit the LDRD website to view upcoming seminars.
Aaron Greco
“Advancing Additive Manufacturing of Metal Alloys through High-Speed in situ Monitoring,” by Materials Scientist Aaron Greco (AMD)
Abstract
Additive manufacturing (AM), or 3-D printing, is a rapidly evolving technology that had been primarily used to make prototypes and is now being used to manufacture production components for various applications. However, the nature of printing parts layer-by-layer, as is done in AM, is inherently prone to introducing defects that diminish the quality and reliability of the part. This project focused on development of advanced monitoring techniques that are capable of predicting defect formation in additive manufacturing of metals by leveraging the high-speed X-ray imaging capabilities at the Advanced Photon Source.
Biography
Aaron Greco is a principal materials scientist and group leader of the Interfacial Mechanics & Materials group in the Applied Materials division. Greco’s research areas include tribology, surface engineering, advanced manufacturing and materials fatigue. He has been with Argonne since 2010, received his B.S. from Iowa State University and Ph.D. from Northwestern University.
Peijun Guo
“Strongly Anisotropic Excitons in Low-Dimensional Hybrid Perovskites,” by Named Fellow Peijun Guo (NST)
Abstract
The need for exquisite control of light is ubiquitous in light-harvesting applications, optoelectronics and information science. Hybrid materials such as low-dimensional organic-inorganic perovskites, which consist of distinct organic and inorganic sublattices, allow for dramatically enhanced light absorption and emission in the visible spectral range. This project used a new dielectric-coating based technique to characterize the refractive index for these materials for the first time. Strong quantum confinement can be easily imparted to hybrid perovskites with the use of organic spacer molecules, leading to a hyperbolic dispersion relation (i.e., the permittivity changes sign with direction). Such naturally occurring, exotic dispersion stems from the extremely anisotropic excitonic behaviors of low-dimensional perovskites and can intrinsically support a large photonic density of states, suggesting low-dimensional hybrid perovskites as excellent candidates for solid-state lighting applications.
Biography
Peijun Guo received his B.E. from Tsinghua University with highest honors in 2009, and his M.S. and Ph.D. from Northwestern University in 2011 and 2016, respectively, all in materials science and engineering. He is currently an Enrico Fermi Named Postdoc Fellow at Argonne National Laboratory. Guo has authored and co-authored more than 50 peer-reviewed journal publications and has been recognized with the Materials Research Society Graduate Student Gold Award and the SPIE Education Scholarship. His research is focused on the design and synthesis of inorganic and hybrid materials for enhanced light-matter interactions, and time-resolved optical studies of excited-state dynamics in complex material systems for energy conversion, optoelectronics and information science.