Diamond at 800 GPa

Abstract

A new compression technique, which enables the study of solids into the TPa regime, is described and used to ramp (or quasi-isentropically) compress diamond to a peak pressure of 1400 GPa. Diamond stress versus density data are reported to 800 GPa and suggest that the diamond phase is stable and has significant material strength up to at least this stress level. Data presented here are the highest ramp compression pressures by more than a factor of 5 and the highest-pressure solid equation-of-state data ever reported.

Refractive index of lithium fluoride ramp compressed to 800 GPa

“…1(b) displays a distinct plateau at 2 lm/ns caused by the drop from the longitudinal to the bulk sound speed as the elastic limit of diamond is exceeded. In this experiment, as in previous experiments, 12 the plateau shows a very constant velocity and the elastic limit is treated as a straightforward drop in the sound speed. Using that assumption, the calculated drive pressure is determined and then forward-propagated to the diamond/LiF boundary, where pressures were impedance matched, thereby determining U t .…”

“…12 This work shows that LiF remains transparent when the ramp is compressed to 800 GPa; the highest pressure under which a transparent insulator has ever been observed. We use a new technique to measure its refractive index at pressures of 30 to 800 GPa.…”

X-ray diffraction of molybdenum under shock compression to 450 GPa

“…Previous shock wave studies of molybdenum provided only constraints on the equation of state 16 or sound velocities 2,9,37 and could not directly determine the stability of different phases. Laserdriven dynamic compression experiments have emerged in recent years as a novel technique for probing the ultra-high pressure behavior of materials [38][39][40] . In laser-shock experiments, the application of pulsed high-powered laser energy ablates the surface of a sample creating a hot, expanding plasma which exerts pressure on the surrounding material resulting in the propagation of a strong shock wave through the sample.…”

Thermal conductivity of diamond under extreme pressure: A first-principles study

“…Diamond has also proven to be an ideal test material for both theoretical [6][7][8] and experimental [9][10][11] high-pressure studies with measured pressures reaching as high as 800GPa [11].…”