Shock-Compressed Diamond: Melt, Insulator-Conductor and Polymeric-Atomic Transitions

Journal Article · Thu Aug 16 04:00:00 EDT 2007 · Nature Physics, vol. 6, no. 1, January 1, 2010, pp. 40-43

OSTI ID:1010391

Eggert, J; Hicks, D G; Celliers, P M; Bradley, D K; McWilliams, R S; Jeanloz, R; Miller, J E; Boehly, T R

Temperatures measured on the shock-Hugoniot of diamond reveal melting between 650 ({+-} 60) GPa and 9000 ({+-} 800) K and 1090 ({+-} 50) GPa and 8400 ({+-} 800) K, with a heat of fusion of {approx} 25 {+-} 10 kJ/mole and a negative Clapeyron slope {partial_derivative}T/{partial_derivative}P|{sub melt} = -5 {+-} 3 K/GPa. Thus, the fluid is denser than the compressed solid, and optical reflectivity measurements show it to be metallic. Hugoniot-temperature measurements extending to over 4000 GPa (40 Mbar) and 115,000 K suggest de-polymerization of a dense covalently-bonded fluid to an atomic state between 10,000 and 30,000 K. These experimental results indicate that carbon present deep inside planets such as Uranus and Neptune could be solid for through-going convection, whereas stable stratification would allow for the presence of fluid metallic carbon at depth; in either case, the presence of carbon could potentially affect planetary seismic normal modes.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA
• Sponsoring Organization: USDOE
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 1010391
• Report Number(s): UCRL-JRNL-234391
• Journal Information: Nature Physics, vol. 6, no. 1, January 1, 2010, pp. 40-43, Journal Name: Nature Physics, vol. 6, no. 1, January 1, 2010, pp. 40-43 Journal Issue: 1 Vol. 6
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CARBON
CONVECTION
DIAMONDS
FUSION HEAT
MELTING
PLANETS
REFLECTIVITY
STRATIFICATION