Ultra-fast x-ray diffraction studies of the phase transitions and equation of state of scandium shock-compressed to 82 GPa
Physical Review Letters American Physical Society 118:2 (2017) 025501
Abstract:
Using x-ray diffraction at the LCLS x-ray free electron laser, we have determined simultaneously and self-consistently the phase transitions and equation-of-state 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.Inelastic response of silicon to shock compression.
Scientific reports Nature Publishing Group 6 (2016) 24211
Abstract:
The elastic and inelastic response of [001] oriented silicon to laser compression has been a topic of considerable discussion for well over a decade, yet there has been little progress in understanding the basic behaviour of this apparently simple material. We present experimental x-ray diffraction data showing complex elastic strain profiles in laser compressed samples on nanosecond timescales. We also present molecular dynamics and elasticity code modelling which suggests that a pressure induced phase transition is the cause of the previously reported 'anomalous' elastic waves. Moreover, this interpretation allows for measurement of the kinetic timescales for transition. This model is also discussed in the wider context of reported deformation of silicon to rapid compression in the literature.Simulations of in situ x-ray diffraction from uniaxially compressed highly textured polycrystalline targets
Journal of Applied Physics AIP Publishing 118:6 (2015) 065902
Electron-phonon equilibration in laser-heated gold films
Physical Review B American Physical Society (APS) 90:1 (2014) 014305
Investigations into rapid uniaxial compression of polycrystalline targets using femtosecond X-ray diffraction
Journal of Physics Conference Series IOP Publishing 500:11 (2014) 112063