Publications by David McGonegle


Ultrafast X-Ray Diffraction Studies of the Phase Transitions and Equation of State of Scandium Shock Compressed to 82 GPa.

Physical review letters 118 (2017) 025501-

R Briggs, MG Gorman, AL Coleman, RS McWilliams, EE McBride, D McGonegle, JS Wark, L Peacock, S Rothman, SG Macleod, CA Bolme, AE Gleason, GW Collins, JH Eggert, DE Fratanduono, RF Smith, E Galtier, E Granados, HJ Lee, B Nagler, I Nam, Z Xing, MI McMahon

Using x-ray diffraction at the Linac Coherent Light Source x-ray free-electron laser, we have determined simultaneously and self-consistently the phase transitions and equation of state (EOS) of the lightest transition metal, scandium, under shock compression. On compression scandium undergoes a structural phase transition between 32 and 35 GPa to the same bcc structure seen at high temperatures at ambient pressures, and then a further transition at 46 GPa to the incommensurate host-guest polymorph found above 21 GPa in static compression at room temperature. Shock melting of the host-guest phase is observed between 53 and 72 GPa with the disappearance of Bragg scattering and the growth of a broad asymmetric diffraction peak from the high-density liquid.


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