Ronald Cohen primarily studies materials through first principles research—computational methods that begin with the most fundamental properties of a system, such as the nuclear charges of atoms, and then calculate what happens to a material under different conditions, such as pressure and temperature. He particularly focuses on properties of materials under extreme conditions such as high pressure and high temperature. This research applies to various topics and problems in geophysics and technological materials.

Some of his work focuses on understanding the behavior of high-technology materials called ferroelectrics—non-conducting crystals with an electric dipole moment similar to the opposite poles found in a common bar magnet. He also looks at minerals in Earth’s deep interior and of materials that display interesting physical and chemical properties. Other researchers use Cohen’s results as a tool to interpret their observations and to design experiments.

Medical imaging, sonar, semiconductors, and other electronics devices can benefit from understanding ferroelectrics. Ferroelectrics are unusual in that their polarity can exist even in the absence of an electric field, and the direction of the dipole can change when an electric field is applied. These useful substances further exhibit the piezoelectric effect—they can translate mechanical energy into electricity. New piezoelectrics have ten times the coupling between mechanical and electrical energy, and could revolutionize medical ultrasound and naval applications. Cohen investigates the physics underlying their intriguing behavior and uses theory to search for even better substances. 

 

Predicting how minerals behave at extreme pressures and temperatures in Earth’s interior is important to interpreting seismic data and to understanding the structure and dynamics of the planet. Cohen calculates what happens, for example, to iron—the major component of Earth’s core; transition metal oxides such as iron oxide (FeO), and high-pressure silicates such as MgSiO3, perovskite, alumina, and silica phases as pressure increases. Some work hones in on the temperature at Earth’s center through the computed elastic properties of iron compared with seismological data.

Cohen obtained a B.Sc. in geology from Indiana University in 1979 and a Ph.D. in geology from Harvard University in 1985. Before coming to Carnegie as a staff scientist in 1990, he was a research associate at the National Research Council from 1985-1987 and a research physicist at the Naval Research Laboratory from 1987 to 1990. For more see the Cohen lab

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Journal of Physical Chemistry Letters cover
September 9, 2019

Washington, DC— New materials can contribute potential solutions to many societal issues—from increasing access to clean drinking water to improving solar panel efficiency. But figuring out how to synthesize them can be a difficult process of trial and error.

Carnegie’s Li Zhu, Timothy Strobel, and Ronald Cohen have created a new tool for predicting pathways to novel materials that could speed this process up significantly. A paper demonstrating the method’s effectiveness is a cover story in The Journal of Physical Chemistry Letters.

Called PALLAS after one of the nicknames for Athena, the Greek goddess of wisdom, their method creates a kind of

March 13, 2019

Carolyn Beaumont, a senior at the Potomac School in McLean VA, won 5th place in the 78th Regeneron Science Talent Search. During the summer of 2018, she worked with Geophysical Laboratory staff members George Cody and Bjorn Mysen on a project to shed light on the molecular details of how water interacts with silicate melts. During her time, she learned how to run all aspects of the experiment, including how to operate a piston cylinder pressure apparatus that generates pressures on the order of 1.5 GPa and temperatures in excess of 1400°C. She also used molecular spectroscopy and nuclear magnetic resonance spectroscopy, to obtain detailed

September 20, 2018

A new Venture Grant has been awarded to the Geophysical Laboratory’s Dionysis Foustoukos and Sue Rhee of the Department of Plant Biology, with colleague Costantino Vetriani of Rutgers University for their project Deciphering Life Functions in Extreme Environments.

Carnegie Science Venture Grants ignore conventional boundaries and bring together cross-disciplinary researchers with fresh eyes to explore different questions. Each grant provides $100,000 support for two years with the hope for surprising outcomes. The grants are generously supported, in part, by trustee Michael Wilson and his wife Jane and by the Ambrose Monell Foundation.

Deep sea hydrothermal vents

Unraveling the properties of fluid metallic hydrogen could help scientists unlock the mysteries of Jupiter’s formation and internal structure. Credit: Mark Meamber, LLNL.
August 15, 2018

Washington, DC—Lab-based mimicry allowed an international team of physicists including Carnegie’s Alexander Goncharov to probe hydrogen under the conditions found in the interiors of giant planets—where experts believe it gets squeezed until it becomes a liquid metal, capable of conducting electricity. Their work is published in Science.

Hydrogen is the most-abundant element in the universe and the simplest—comprised of only a one proton and one electron in each atom. But that simplicity is deceptive, because there is still so much to learn about it, including its behavior under conditions not found on Earth.

For example, although hydrogen on the

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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.

Staff Associate Kamena Kostova joined the Department of Embryology in November 2018. She studies ribosomes, the factory-like structures inside cells that produce proteins. Scientists have known about ribosome structure, function, and biogenesis for some time. But, a major unanswered question is how cells monitor the integrity of the ribosome itself. Problems with ribosomes have been associated with diseases including neurodegeneration and cancer. The Kostova lab investigates the fundamental question of how cells respond when their ribosomes break down using mass spectrometry, functional genomics methods, and CRISPR genome editing.

Kostova received a B.S. in Biology from the

Sally June Tracy applies cutting-edge experimental and analytical techniques to understand the fundamental physical behavior of materials at extreme conditions. She uses dynamic compression techniques with high-flux X-ray sources to probe the structural changes and phase transitions in materials at conditions that mimic impacts and the interiors of terrestrial and exoplanets. She is also an expert in nuclear resonant scattering and synchrotron X-ray diffraction. She uses these techniques to understand novel behavior at the electronic level.  Tracy received her Ph.D. from the California Institute of

The Ludington lab investigates complex ecological dynamics from microbial community interactions using the fruit fly  Drosophila melanogaster. The fruit fly gut carries numerous microbial species, which can be cultured in the lab. The goal is to understand the gut ecology and how it relates to host health, among other questions, by taking advantage of the fast time-scale and ease of studying the fruit fly in controlled experiments. 

Nick Konidaris is a staff scientist at the Carnegie Observatories and Instrument Lead for the SDSS-V Local Volume Mapper (LVM). He works on a broad range of new optical instrumentation projects in astronomy and remote sensing. Nick's projects range from experimental to large workhorse facilities. On the experimental side, he recently began working on a new development platform for the 40-inch Swope telescope at Carnegie's Las Campanas Observatory that will be used to explore and understand the explosive universe.

 Nick and his colleagues at the Department of Global Ecology are leveraging the work on Swope to develop a new airborne spectrograph that will be