May 19, 2017
Colloquium Speaker: Russell J. Hemley
Russell J. Hemley explores the nature of materials in extreme pressure and temperature environments, and the implications of those findings for physics and chemistry, earth and planetary science, and biology. He received his B.A. from Wesleyan University (1977), and M.A. (1980) and Ph.D. (1983) from Harvard University, all in chemistry. He worked at the Carnegie Institution since 1984-2016, and is a Research Professor in the School of Engineering and Applied Sciences, The George Washington University. He is also the Director of the Capital/DOE Alliance Center (CDAC) funded by the DOE-NNSA and of Energy Frontier Research in Extreme Environments (EFree), a DOE Energy Frontier Research Center. His honors include membership in the National Academy of Sciences (2001), Balzan Prize in Mineral Physics (2005), Corresponding Fellow of the Royal Society of Edinburgh (2008), Honoris Causa Professor of the Russian Academy of Sciences (2008), and the Percy W. Bridgman Award (2009). He has published approximately 630 scientific papers. He has been a member of the JASON Advisory Group since 2003, and currently serves as Chair.
Extreme pressures and temperatures produce profound effects on structure, bonding and electronic character of atoms and molecules, molding matter to make new materials. A growing number of novel materials and phenomena are being documented over the broad range of conditions, including both static and dynamic multimegabar (e.g., >300 GPa) pressures that can now be generated in the laboratory. Examples include unexpected transitions between insulating and metallic phases, new superconductors and low-dimensional materials, and novel structural and superhard materials. Of particular interest have been pressure-induced transitions in the putatively simple systems hydrogen and water. Altogether, these studies have implications for problems in physics and chemistry, planetary science, geoscience, astrophysics, and even soft matter and biology, and the new materials being discovered may find potential applications in energy and other technologies. In this effort, accelerator-based x-ray, infrared, neutron scattering, and large-scale dynamic compression facilities are allowing new types of measurements to be made as well as more extreme environments to be reached in the laboratory.