Hugoniot and sound velocity measurements of bismuth in the range of 11–70 GPa

Abstract

Plate impact experiments in backward-impact geometry were performed on bismuth (Bi) in the pressure range of 11–70 GPa. The bismuth sample used as flyer impacted a LiF window, and the impact velocity and particle velocity at interface were simultaneously measured by a distance interferometer system for any reflector. Hugoniot and sound velocity data were extracted from the observed particle velocity profiles. The obtained plot of shock velocity (D) versus particle velocity (u) showed a discontinuity at u ≈ 0.9 km/s, corresponding to a pressure of ∼27 GPa. Furthermore, plate impact experiments in forward-impact geometry were conducted to measure sound velocities of bismuth. The extracted sound velocity data from backward and forward-impact experiments showed a transition from longitudinal to bulk sound velocity (18 GPa–27 GPa), and the pressure of transition to bulk sound velocity is consistent with the pressure of D-u knee at u ≈ 0.9 km/s. This D-u discontinuity at u ≈ 0.9 km/s is attributed to shock induced melting, and the onset and completion of melting on bismuth Hugoniot are estimated around 18 GPa and 27 GPa, respectively.