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.

Direct Observation of Melting in Shock-Compressed Bismuth With Femtosecond X-ray Diffraction

“…However, these estimates were obtained from the modeling of Bi wave profiles, which can be very complex [32], and which also require assumptions as to which profile features are indicative of melting. This is non-trivial, and even in the most recent study [8] it was not possible to say whether the "knees" seen in the release wave profiles definitely resulted from melting of Bi-V, but only that this was a possibility.…”

“…We studied melting of Bi on release from the highpressure body-centered cubic (bcc) Bi-V phase, as recently reported by Tan et al [8], which was obtained by shocking the Bi to pressures of between 8 and 14 GPa (see Fig. 1).…”

“…1). There have been no direct observations of shock melting in Bi via diffraction, but numerous wave profile [6][7][8] and pyrometry [9] studies have reported melting, or its absence, on both compression and release. The indirect nature of these measurements means that the timescale of melting in Bi remains poorly constrained, with inferred melting times ranging from tens to hundreds of nanoseconds [10,11].…”

Experimental investigation of the shock response of bismuth under one-dimensional shock-loading

“…Bismuth is a post-transition metal which shows a series of clear phase changes under relatively low pressure shock loading, key amongst which are [1][2][3][4]: phase I II (rhombohedral monoclinic) [~2.6 GPa]; phase II III (body-centred tetragonal; bct) [2.8 GPa]; phase III V (body-centred cubic; bcc) [c.a. 7 -7.7 GPa].…”

“…For example, Tan et al [2] undertook a series of conventional and reverseorientation plate impact tests to investigate the dynamic response of bismuth in the pressure range 11-70 GPa. A two-phase Hugoniot was identified in the U s -u p plane, with differing linear responses above and below u p = 0.9 mm/ s (corresponding to ~27 GPa).…”