Diamond melting response at multimegabar pressures is of strong interest for understanding the interiors of giant planets and carbon-rich exoplanets, and for applications related to inertial confinement fusion. However, the high-pressure melting behavior of diamond remains poorly understood. Using plate impact experiments at the Sandia Z facility to achieve stresses up to 870 GPa, we show that melting onset in shock compressed [100] diamond single crystals and polycrystalline diamond occurs at 690 GPa. The [110] diamond response differs at stresses below the melting onset, showing that the approach to shock-induced melting depends on crystal orientation. In the solid-liquid mixed phase, the results for all diamond sample types coincide, demonstrating that the hydrodynamic assumption is appropriate after the melting onset. Our results provide an important benchmark for future theoretical studies, including the development of accurate multiphase equation of state models for diamond at high pressures and high temperatures.

Close

PrevNext

View figure in article

• Crystal melting
• Shock waves
• Diamond
• Hugoniot measurements