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High Pressure

High pressure science and technology has been a major thrust area at the Geophysical Laboratory since the founding of the department.  The Laboratory continues to develop and explore the field of extreme environments.

The Geophysical Laboratory has made important advances in the growth of diamond by chemical vapor deposition (CVD).  Methods have been developed to produce single-crystal diamond at low pressure having a broad range of properties. Video- "Growing Synthetic Diamonds"

Researchers studying the Earth's core have found that neither the liquid outer core nor the solid inner core is as dense as would be expected if the core were pure iron. Lighter elements must be present. But which ones? Melted samples are subjected to pressures up to 250,000 atmospheres.

Scientists at the Geophysical Laboratory use the dedicated facilities of the Los Alamos and Oak Ridge National Laboratories for the study of neutron scattering of condensed matter.

 

A broad range of optical spectroscopy techniques are used by scientists at the Geophysical Laboratory studying high-pressure phenomena. These techniques include absorption, reflectivity, and emission spectra over a wide spectral range (240-16,000 nm), infrared absorption spectroscopy, and Raman spectroscopy -- These techniques can be used at combined high pressures and variable temperatures from cryogenic to laser heating conditions.

Scientists run hydrothermal organic chemistry experiments at temperatures ranging from 50 up to 250 °C and at pressures from 2-3 MPa up to 400 MPa.

 

Probing minute samples at ultrahigh pressures requires high-energy beams from synchrotrons such as the Advanced Photon Source (APS) at Argonne National Laboratory. Geophysical Laborator yscientists have remained at the forefront of developing these new analytical tools.

High Pressure News

 

Washington, D.C., 23 June 2016 — New work published in Physical Review Letters by the Geophysical Laboratory’s Alexander Goncharov and University of Edinburgh’s Stewart McWilliams measures the conditions under which hydrogen undergoes this transition in the lab and finds an intermediate state between gas and metal, which they’re calling “dark hydrogen.”

Washington, D.C., 8 June 2016— Using laboratory techniques to mimic the conditions found deep inside the Earth, a team of Geophysical Laboratory scientists led by Ho-Kwang “Dave” Mao has identified a form of iron oxide that they believe could explain seismic and geothermal signatures in the deep mantle.

Washington, D.C., 1 June 2016— Earth's magnetic field shields us from deadly cosmic radiation, and without it, life as we know it could not exist here. The motion of liquid iron in the planet’s outer core, a phenomenon called a “geodynamo,” generates the field. But how it was first created and then sustained throughout Earth’s history has remained a mystery to scientists. New work published in Nature from a team led by the Geophysical Laboratory's Alexander Goncharov sheds light on the history of this incredibly important geologic occurrence.

Nagoya, Japan, 11 May 2016—Ronald Cohen was an invited speaker at the AMTC5 workshop in Nagoya May 11-13, 2016 and spoke on "Strong Coupling Ferroelectrics, How They Work and How They Can Be Improved."  He then visited ELSI (Earth and Life Sciences Institute) at Tokyo Tech and spoke on “First-principles studies of the deep Earth.”

Presentations

Russell J. Hemley "High-Pressure Geoscience: New Tools and Expanding Outreach", Workshop on Long Range Plans for High Pressure earth Sciences (Tempe, AZ, March 2-4, 2009).

Russell J. Hemley "Hydrogen, SUSSP 2008: High Pressure Physics", Scottish Universities Summer School in Physics No. 63 (Isle of Skye, Scottland, May 26-June 6, 2008).

Russell J. Hemley "New Light on Materials under Extreme Conditions: Synchrotron Radiation and High Pressure", ICTP (Trieste, November, 2006).

Russell J. Hemley "Overview of New Developments and Future Prospects in High Pressure Research ", Minerva School (Ein Guedi, March, 2006).