UConn Physics Colloquium
“Transport properties of liquid transition metals at extreme conditions: a lesson from metallic glasses with the forbidden symmetry”
Reynold E. Silber
Department of Geology and Geophysics, Yale University, New Haven CT, USA 06511
The Earth’s core is a giant heat engine that supports the existence of life on our planet by providing heat to drive mantle convection, plate tectonics and volcanism. The convection of a liquid iron (Fe) alloy in the outer core generates the Earth’s magnetic field. However, transport properties of liquid Fe-alloys (e.g., electrical, thermal and viscous transport properties) at extreme core conditions are some of the least constrained parameters. The high pressure experimental measurements of the transport properties are extremely challenging and a general theoretical understanding of the structures of liquid transition metals is still incomplete. Recent successful electrical resistivity measurements of liquid Fe, Ni and Fe-Si alloy at pressures up to 24 GPa show the invariant electrical resistivity along the melting boundaries. It was demonstrated that the Icosahedral Short Range Order (ISRO) structures in liquid transition metals and alloys strongly modulate transport properties at extreme conditions. Supporting evidence for the presence of the ISRO in the Earth’s and other terrestrial outer cores comes from the recently discovered quasi-crystalline phases in natural metallic glasses with the forbidden symmetry, previously considered impossible to exist in nature. However, the existence of forbidden fivefold symmetry is not possible without super-cooling of metallic glass forming liquids that contain ISRO structures. Thus, metallic glasses represent one of the convergence points between planetary science and materials science. Here, I first discuss a new paradigm imposed by the ISRO structures on the transport properties of the outer cores of terrestrial planetary bodies. The discussion is then extended toward the important role ISROs play in formation of metallic glasses with exotic properties. Furthermore, I examine the potential application of high pressures toward manufacturing of metallic glasses with customizable concentration of structures with ISRO or any other forbidden symmetry. Considering the important role of metallic glasses in the high tech industry, this research has significant cross-disciplinary implications.
Friday, February 7, 2020
3:30 P.M.
Biology Physics Building
Room BPB-131
Cookies will be served prior to the talk, at 3:00 p.m. outside BPB-131
For more information, contact: Anna Huang at anna.huang@uconn.edu