Scientists have made a breakthrough in understanding how diamonds melt. This new knowledge could help triple the energy output from laser-driven nuclear fusion.
Researchers at Lawrence Livermore National Laboratory (LLNL) studied how diamonds behave under extreme pressure. They found that diamonds melt at pressures three times greater than those found at Earth's core.
Marius Millot, an LLNL scientist, explained that they compressed tiny diamond samples. These samples reached temperatures hotter than the sun's surface and pressures higher than the centers of Neptune and Uranus. Even under these conditions, they could still measure the diamond's atomic structure, temperature, density, and how it reflected light.
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Start Your News DetoxDiamond's Role in Fusion and Planets
Diamonds are more than just jewels. This super-hard form of carbon is used to encase fuel in inertial confinement fusion. Scientists also believe diamonds rain down deep inside ice giant planets like Neptune and Uranus. In both situations, the material faces immense pressures.
For a long time, experiments and computer simulations disagreed on how diamonds behave under these conditions. This new study has resolved two major differences in the field. The experimental results now match simulations based on quantum mechanics.
Applying these findings to inertial confinement fusion could triple the energy gain. Also, this new understanding of diamond's high-pressure phases could change how scientists model the insides of planets.
LLNL has been studying diamond's extreme behavior for decades. About 20 years ago, lab scientist Jon Eggert found that diamond's density increased when it melted.
Millot noted that this is unusual for most materials. However, liquid water is denser than ice, which is why ice cubes float. Eggert's discovery meant that diamond would float in liquid carbon at high pressures.
Solving a Long-Standing Mystery
While Eggert's work was important, it also raised new questions. One big puzzle was a 20% difference between the observed and predicted melting temperatures of diamond.
Millot said that even with the most advanced computer simulations, theorists could not match the experimental results.
The new study, published in Nature, solves this puzzle. It shows that the diamond structure remains stable up to 1 terapascal (TPa) of pressure. This contradicts earlier reports of a change to a different phase called BC8, which was thought to be stable above 1 TPa.
The study provides evidence for melting caused by shock waves. It also shows a slight drop in melting temperature as pressure increases near 7,300 Kelvin.
Researchers believe their work offers important benchmarks for quantum simulations of materials under extreme conditions. This has implications for understanding planetary interiors. They also noted that their improved understanding of diamond melting could help achieve higher energy gain in laser-driven nuclear fusion.
