Squeezing information from materials under extreme pressure

By Jared SagoffJuly 1, 2010

By compressing tiny amounts of material between two diamond anvils, scientists have for more than three decades been able to achieve pressures of over 1 million atmospheres. The physical changes and phase transitions that occur under such pressures test theories of solid-state physics and shed light on conditions in planetary interiors. But to gain useful information from highly compressed samples, researchers need probes that resolve fine details of the materials' structure.

A team of scientists from Argonne, the Carnegie Institution of Washington, National Cheng Kung University (Taiwan), and Stanford University has now used nanoscale x-ray beams at the U.S. Department of Energy’s Advanced Photon Source (APS) at Argonne National Laboratory to resolve, on a scale of 250 nanometers, different elements in a mixture of metals, and to obtain diffraction patterns of similarly-sized single crystals in a powder. Such techniques make it feasible to perform measurements at even higher pressures, using smaller diamond anvil cells.

The success of these techniques for high-resolution x-ray studies of materials under extreme pressures makes it feasible to go to still higher pressures, using smaller diamond faces. The researchers think it will ultimately be realistic to get useful data from experiments at terapascal pressures, an order of magnitude higher than has been achieved to date.

Citation Information: Lin Wang et al., "Nanoprobe measurements of materials at megabar pressures," PNAS 107, 6140 (2010).