Publications by Justin Wark

Identification of phase transitions and metastability in dynamically compressed antimony using ultrafast x-ray diffraction

Physical Review Letters American Physical Society 122 (2019) 255704

AL Coleman, R Briggs, RS McWilliams, D McGonegle, CA Bolme, AE Gleason, DE Fratanduono, RF Smith, E Galtier, HJ Lee, B Nagler, E Granados, GW Collins, JH Eggert, J Wark, MI McMahon

Ultrafast x-ray diffraction at the LCLS x-ray free electron laser has been used to resolve the structural behavior of antimony under shock compression to 59 GPa. Antimony is seen to transform to the incommensurate, host-guest phase Sb-II at ∼11 GPa, which forms on nanosecond timescales with ordered guest-atom chains. The high-pressure bcc phase Sb-III is observed above ∼15 GPa, some 8 GPa lower than in static compression studies, and mixed Sb-III/liquid diffraction are obtained between 38 and 59 GPa. An additional phase which does not exist under static compression, Sb-I', is also observed between 8 and 12 GPa, beyond the normal stability field of Sb-I, and resembles Sb-I with a resolved Peierls distortion. The incommensurate Sb-II high-pressure phase can be recovered metastably on release to ambient pressure, where it is stable for more than 10 ns.

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