LLNL Researchers Measure Diamond Melting at Pressures Three Times Earth's Core
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Lawrence Livermore National Laboratory researchers have measured how diamond melts at pressures three times greater than Earth's core. The measurements, published in Nature Physics, bring experimental data into close agreement with quantum mechanical simulations, resolving a 20-year-old discrepancy in diamond research.
Key Facts
- Earlier laboratory measurements of diamond melting temperatures differed from theoretical predictions by roughly 20%.
- Sandia National Laboratories' Z machine experiments had suggested diamond passes through another crystalline structure before melting into liquid carbon.
- About 20 years ago, LLNL scientist Jon Eggert and colleagues reported that diamond becomes denser when it melts.
- LLNL scientist Marius Millot said liquid water is denser than ice, an analogy for diamond floating in liquid carbon at high pressure.
High-Pressure Diamond Measurements
Researchers at Lawrence Livermore National Laboratory used shock compression on tiny diamond samples at pressures three times greater than Earth's core. They recorded temperatures hotter than the surface of the sun and pressures higher than the center of Neptune and Uranus. The measurements resolved two long-standing discrepancies in diamond research. The experimental data now closely match simulations based on quantum mechanics.
Twenty Years of Conflicting Data
About 20 years ago, LLNL scientist Jon Eggert and colleagues made pioneering diamond melting experiments at high pressure. Their laboratory melting temperatures differed from theoretical predictions by roughly 20%. LLNL scientist Marius Millot said even advanced computer simulation techniques could not reproduce the experiments. Separate experiments at Sandia National Laboratories' Z machine suggested diamond passes through another crystalline structure before melting into liquid carbon. Computer simulations supported that interpretation, and the new LLNL measurements now resolve the conflict.
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LLNL Researchers Measure Diamond Melting at Pressures Three Times Earth's Core
