Scientists at Lawrence Livermore National Laboratory have measured how diamond melts under pressures far beyond those found at Earth’s core, according to ScienceDaily. The new study, published in Nature Physics, helps resolve two long-running disagreements about how the material behaves under extreme conditions.
Researchers used laser-driven dynamic compression experiments at the University of Rochester’s Laboratory for Laser Energetics to shock tiny diamond samples. The team recorded atomic structure, temperature, density and optical reflectivity in conditions that lasted only about a billionth of a second.
According to the report, the new measurements bring laboratory results into close agreement with quantum-mechanics-based simulations and confirm an updated melting temperature that matches theory far better than earlier experiments did. A prior finding that diamond became denser when it melted was also reaffirmed.
The study also addressed another question raised by earlier work at Sandia National Laboratories. Instead of passing through another crystalline phase before melting, the diamond kept its structure until it became liquid carbon. Researchers said that may be because the single shock did not give the sample time to change structure.
The results could have practical value for inertial confinement fusion research, where diamond capsules are used in experiments that aim to compress fuel to extreme conditions. The findings may also improve models of the interiors of planets such as Neptune and Uranus.
