Recovery of a high-pressure phase formed under laser-driven compression

Abstract

The recovery of metastable structures formed at high pressure has been a long-standing goal in the field of condensed matter physics. While laser-driven compression has been used as a method to generate novel structures at high pressure, to date no high-pressure phases have been quenched to ambient conditions. Here we demonstrate, using in situ x-ray diffraction and recovery methods, the successful quench of a high-pressure phase which was formed under laser-driven shock compression. We show that tailoring the pressure release path from a shock-compressed state to eliminate sample spall, and therefore excess heating, increases the recovery yield of the high-pressure ω phase of zirconium from 0% to 48%. Our results have important implications for the quenchability of novel phases of matter demonstrated to occur at extreme pressures using nanosecond laser-driven compression.

Development of slurry targets for high repetition-rate XFEL experiments

“…For future high-repetition rate operation where the XRD data is integrated over many shots to enhance signal-tonoise, this azimuthal intensity variation is expected to smooth out to produce a powder pattern suitable for Rietveld refinement analysis (26,58). Shown in Fig.…”

“…Here, we describe combined laser-shock and X-ray diffraction (XRD) measurements on the Matter in Extreme Conditions (MEC) endstation at the Stanford LCLS XFEL, which provide a direct measure of granular density and crystal structure as a function of increasing shock pressure (25,26). Temperature in the sample is constrained by comparing crystal structure evolution as a function of sample density with recent similar data from full-density samples (53).…”

“…The use of XFEL sources, which deliver high-flux Xray pulses (10 12 -10 13 photons at ∼6-25 keV over 50fs) within a narrow photon-energy bandwidth (∆E/E ∼ 2×10 −3 ), has been transformative for the study of dynamic material properties and high energy density (HED) science (47). Combined with high power laser drivers, this has allowed for measurements previously thought possible only when performed under static compression and integrated in time, including complex crystallography (8,13,25,26,30,60), precise spectroscopy (61), and high-resolution imaging (10,48,55) in single-shot dynamic compression experiments.…”

“…However, the nature of this design requires initial target ductility and so precludes the study of a whole class of brittle ceramics materials. In addition, the production of extended ribbon targets will produce samples with a characteristic micro-structural texture and an x-ray texture pattern which may be challenging for Rietveld refinement analysis, and consequently for determination of phase fraction (26,58).…”

Molecular dynamics simulations of inelastic x-ray scattering from shocked copper

“…An enduring and growing interest in this field is driven not only by a desire for fundamental understanding of the behaviour of matter under extreme conditions, but also by the goal of linking such knowledge to a description of the interiors and dynamics of planets within our own solar system and beyond [10][11][12][13] . On a practical front there also exists the prospect of finding and recovering new high-pressure phases that are metastable under ambient conditions, opening novel routes for materials synthesis [14][15][16][17][18] .…”