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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

 

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.”

Washington, D.C., 18 March 2016—Geophysical Laboratory team Tim Strobel, Venkat Bhadram, and alum DuckYoung Kim, has discovered a new transition metal, titanium pernitride, TiN2, which is ultraincompressible and could be a potential superhard material.

Washington, D.C., 8 February 2016—A team including the Geophysical Laboratory's Qiaoshi “Charles” Zeng and Ho-kwang “Dave” Mao, among others, is trying to figure out the rules that govern metallic glass’s creation. They are doing this by looking at metallic glasses under extreme pressures. High-pressure research can be used to probe structure on an atomic level and understand a material’s state of order or disorder.

Using diamond-anvil cell technology combined with X-ray absorption spectroscopy, a research team led by the Geophysical Laboratory's Reinhard Boehler was able to demonstrate a melting temperature for iron of 3,090 K (about 5,100 degrees Fahrenheit) in the 100-gigapascal pressure range (about a million times normal atmospheric pressure).

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).