Compression-rate dependence of pressure-induced phase transitions in Bi

Rachel J Husband,Emma E Mcbride,Earl F O’Bannon,Alba S J Méndez,William J Evans,Zsolt Jenei,Hanns-Peter Liermann,Zuzana Konôpková,Magnus J Lipp

doi:10.1038/s41598-021-94260-y

Abstract

It is qualitatively well known that kinetics related to nucleation and growth can shift apparent phase boundaries from their equilibrium value. In this work, we have measured this effect in Bi using time-resolved X-ray diffraction with unprecedented 0.25 ms time resolution, accurately determining phase transition pressures at compression rates spanning five orders of magnitude (10–2–103 GPa/s) using the dynamic diamond anvil cell. An over-pressurization of the Bi-III/Bi-V phase boundary is observed at fast compression rates for different sample types and stress states, and the largest over-pressurization that is observed is ΔP = 2.5 GPa. The work presented here paves the way for future studies of transition kinetics at previously inaccessible compression rates.

Highlights

It is qualitatively well known that kinetics related to nucleation and growth can shift apparent phase boundaries from their equilibrium value
We performed a series of static compression experiments to determine the Bi-III/Bi-V phase boundary for different loading conditions (Fig. 1), which allows for a direct comparison with results from our diamond anvil cells (dDACs) experiments
A higher Bi-III/Bi-V transition pressure is observed in the quasi-hydrostatic samples compared to the sample loaded in Ar, with an even lower transition pressure observed in the sample loaded without a pressuretransmitting medium (PTM) (Table 1)

Summary

Introduction

It is qualitatively well known that kinetics related to nucleation and growth can shift apparent phase boundaries from their equilibrium value. We have measured this effect in Bi using timeresolved X-ray diffraction with unprecedented 0.25 ms time resolution, accurately determining phase transition pressures at compression rates spanning five orders of magnitude (10–2–103 GPa/s) using the dynamic diamond anvil cell. Recent time-resolved X-ray diffraction studies of shock- and ramp-compressed samples have revealed interesting compression-rate dependent phenomena such as shifts of phase transition b oundaries[1], the formation of metastable phases[2,3], and the adoption of alternative phase-transforming pathways[2,3,4]. The behavior of Bi at intermediate strain rates remains essentially unexplored Access to this strain-rate regime is possible using piezo-driven dynamic diamond anvil cells (dDACs), which can generate compression rates up to 160 TPa/s (strain rates of ~ 102 s−1)[5]. Bi-III was initially reported to form on shock release[4], subsequent studies determined the Bi-V/Bi-I transition to proceed through the high temperature Bi-II’ p hase[3], or via the Bi-V/Bi-M/Bi-II/Bi-II′/Bi-I structural s equence[16]

Methods

Results

Conclusion