Bulletin of the American Physical Society
22nd Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 67, Number 8
Monday–Friday, July 11–15, 2022; Anaheim, California
Session W01: Phase Transitions in Non-MetalsRecordings Available
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Chair: Federica Coppari, Lawrence Livermore Natl Lab Room: Anaheim Marriott Platinum 5 |
Thursday, July 14, 2022 4:00PM - 4:15PM |
W01.00001: High-pressure phase transition of magnesium fluoride under shock compression Nobuaki Kawai, Sota Takagi, Sally J Tracy, Takamichi Kobayashi, Kouhei Ichiyanagi Shock compression was applied to single-crystal magnesium fluoride (MgF2) in the (100) and (111) directions by using guns, and the propagating shock wave profiles were measured. In the (100) compression, a kink originating from the phase transition was observed on the shock wave front. The shock compression state after the phase transition was in good agreement with the compression curve of the PdF2 phase predicted from theoretical calculations. In the (111) compression, although the formation of a multi-wave structure associated with the phase transition was not observed on the shock wave front, the shock compression state asymptotically approaches the theoretical compression curve of the PdF2 phase as the shock pressure increases. X-ray diffraction measurements of polycrystalline MgF2 under shock compression confirmed the formation of the PdF2 phase under shock compressed state. It was also confirmed that the phase transition to the α-PbO2 structure was observed during the pressure release process, instead of back-transition to the initial rutile structure. |
Thursday, July 14, 2022 4:15PM - 4:30PM |
W01.00002: In situ X-ray diffraction of Al2O3 during laser compression and release Anirudh Hari, Rohit Hari, Saransh Singh, Joel V Bernier, Raymond F Smith, Thomas S Duffy, Todd C Hufnagel, June K Wicks
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Thursday, July 14, 2022 4:30PM - 4:45PM |
W01.00003: Transformation mechanisms for the pressure-induced phase transition in single crystal CdS Marcus Knudson, Dane V Morgan, Tommy Ao, Mark A Rodriguez, David O Montes de Oca Zapiain, J Matthew D Lane Cadmium Sulfide is a well-studied material which undergoes a solid-solid phase transition from wurtzite to rock salt structures between 3 and 9 GPa. Here we describe the results of dynamic x-ray diffraction (XRD) experiments performed at the Dynamic Compression Sector (DCS) on single crystal CdS shocked along both the c- and a-axis. An automated machine language based regression tool, capable of identifying the lattice and orientations of the underlying structure from multicomponent experimental diffraction patterns, was used to identify orientation relations between the parent and daughter phases. The results provide unique insight into the transformation mechanisms of this solid-solid phase transition and the relationship of these mechanisms to the elastic/inelastic deformation and kinetics of the transition. |
Thursday, July 14, 2022 4:45PM - 5:00PM |
W01.00004: Time resolved measurement of the 1.4 micron absorption band in water during the shock-induced liquid to ice-VII phase transition Brandon M LaLone, Jason G Mance, Darrel Ramsey, Dan Dolan Reverberation compression of a thin water layer, sandwiched between sapphire windows under plate impact, transitions the water from a liquid to a supercooled liquid to solid ice vii. We measured the transmission spectrum of the 1.4 micron absorption band during this transformation using a spectrum to time mapping technique which consists of a train of supercontinuum laser pulses sent through a dispersive spool of optical fiber, a photo detector and a digital oscilloscope. The fiber fed and chirped laser pulses are double passed through the water cell which is compressed with the impactor of a light gas gun and recorded on the oscilloscope. The spectrum changes only slightly during compression to a supercooled liquid, it then more substantially red shifts and narrows as ice vii forms. The dynamic spectrum is compared with prior diamond anvil cell data. |
Thursday, July 14, 2022 5:00PM - 5:15PM |
W01.00005: Real-time latent heat emission during dynamic compression freezing of water Erin J Nissen, Brandon M La Lone, Jason G Mance, Dan Dolan The temperature of liquid water was measured during quasi-isentropic compression for the first time. Compression was achieved through multiple shock wave loading using sapphire windows, where photon Doppler velocimetry was collected at the liquid/window interface and the radiance was simultaneously collected from a ZrF fiber on an amplified liquid nitrogen cooled InSb detector. The results show ice clusters form at pressures below the previously defined metastable limit of 6 – 7 GPa for homogeneous nucleation of ice VII. We also show the water is not hypercoooled as previously described. Instead, the latent heat from solidification brings the temperature to the liquid-ice VII melt line, where it remains with increasing pressure. We suggest an alternative hypothesis to corroborate the results presented here with previous work on dynamic compression freezing of liquid water. |
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