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 I04: Temperature and XRD Measurements Informing EOSRecordings Available
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Chair: June Wicks, Johns Hopkins University Room: Anaheim Marriott Platinum 2 |
Tuesday, July 12, 2022 9:15AM - 9:30AM |
I04.00001: Hugoniot states and sound velocities in shock-compressed soda lime glass: Melting and liquid-state response Pritha Renganathan, Thomas S Duffy, Yogendra M Gupta Commercial silica-rich glasses contain significant fractions of additional oxide cations such as Na and Ca. In particular, soda lime glass (SLG) consists of approximately 71% SiO2 by weight. To examine the effect of these cations on the shock compression response, plate impact experiments were conducted to determine the high-pressure Hugoniot states and longitudinal sound speeds in shock compressed SLG. The Hugoniot states from 40 – 120 GPa determined from transmitted wave profiles are described very well using a linear Us-up relationship, with no features indicative of a phase transformation. However, the longitudinal sound speeds measured to 90 GPa showed a marked decrease between 52 and 58 GPa, providing experimental evidence for an amorphous solid to liquid transformation. Using the liquid state Hugoniot and sound speeds, the Mie-Grüneisen EOS was determined for liquid SLG. Our results show that the network modifying cations (1) inhibit the crystalline phase transformation observed in shocked fused silica and (2) lower the stress threshold for melting in silica-rich glasses under shock compression. Additionally, sound speed measurements provide a good approach to examine the melting transition in shock compressed amorphous solids, difficult to discern using x-ray diffraction. |
Tuesday, July 12, 2022 9:30AM - 9:45AM |
I04.00002: Structural Stability of Shock Compressed Noble Metals: Role of Microstructural Changes Yogendra M Gupta, Surinder M Sharma, Stefan J Turneaure, Michael Winey The structural stability of noble metals to very high pressures under static and shock compression has been widely accepted for a long time, resulting in their use as pressure markers. We present a summary of in situ x-ray diffraction (XRD) results – obtained at the Dynamic Compression Sector located at the Advanced Photon Source – on shock compressed Au, Ag, and Cu that reveal a fcc to bcc transformation with an onset stress between ~150-180 GPa; the fcc-bcc transformation was not observed for Pt shock compressed to over 380 GPa. Furthermore, the XRD results for Au, Ag, and Cu show a copious increase in stacking faults (SFs) before transformation to the bcc structure. In contrast, shock compressed Pt – having much higher SF energy, compared to the other three metals – remains largely free of SFs and retains the fcc structure. These findings suggest that SF formation promotes the fcc-bcc transformation in shock compressed noble metals. Therefore, the role of deformation-induced microstructural changes – an integral aspect of shock compression – needs to be carefully considered in high pressure structural transformations. |
Tuesday, July 12, 2022 9:45AM - 10:00AM |
I04.00003: Temperature measurements on shocked two-phase Ce Brian J Jensen, Matthew T Beason, Tom M Hartsfield, Robert Smalley, Frank J Cherne, Casey Shoemaker, Jason C Cooley The ability to understand and predict the response of matter at extreme conditions requires knowledge of a materials equation-of-state (EOS) including the location of phase boundaries, transitions kinetics, and accurate measurements of temperature at pressure. Recent developments in optical pyrometry have provided methods for measuring temperature in the shocked state, and these have been used to study the phase diagram for some metals including cerium. Cerium has received significant attention because it exhibits a rich phase diagram that includes an anomalous melt boundary and a low-pressure shock-melt transition. In this work, we continue our study of shock-melting using optical pyrometry to measure the temperature and stress states for two-phase cerium (γ-Ce and β-Ce) shocked into the high-pressure liquid phase. These results will be compared to the previously measured results for single phase Ce (γ-Ce) with the goal of gaining further insight into the shock melt transition and associated kinetics. Details of the experimental methods, analysis, and results will be presented (LA-UR-21-30567). |
Tuesday, July 12, 2022 10:00AM - 10:15AM |
I04.00004: Electrical conductivity of Sn at high pressure and temperature Minta C Akin, Ryan S Crum, David A Brantley, Vu Tran, Ricky Chau Temperature and conductivity at high pressure-temperature conditions are yet to be fully understood. We discuss recent electrical conductivity results, and the effect of skin depth, under dynamic loading conditions. Consideration of the skin depth has been neglected in previous dynamic electrical conductivity studies; by using much thinner films and improving signal-to-noise we are able to address this issue. These improvements enabled us to observe the conductivity changes related to solid-to-solid and solid-to-liquid phase transitions in Sn. We also discuss the relevance of the Wiedemann-Franz law to our experiments and compare against thermal transport dependent temperature measurements from previous work. |
Tuesday, July 12, 2022 10:15AM - 10:30AM |
I04.00005: Capability Development using Dynamic X-ray Diffraction of Bi on NIF Karlene R Maskaly, Amy L Coleman, Damian C Swift, Raymond F Smith, Amy E Jenei, Martin G Gorman, Joel V Bernier, Saransh Singh, Kazem Alidoost, Tom Lockard, Sebastien Hamel, Andrew Krygier, Jon H Eggert, James M McNaney The TARDIS platform on the National Ignition Facility (NIF) is a capability that can provide X-ray diffraction images of laser-shocked samples at two separate times during a dynamic loading path. This capability has proven valuable at providing insight into the physical state and behavior of a wide range of solid/liquid materials under dynamic loading conditions, specifically shock and shock-ramp experiments. While NIF has the capacity to achieve extremely high pressures, it is desirable to control the level of an initial shock precisely, to probe the equation of state, phase diagram, and kinetic behavior of materials starting at relatively low pressures (<100GPa). However, achieving a steady low-pressure drive can be challenging. To develop and refine this capability, bismuth was chosen as a target material due to its rich phase diagram at low pressures that presents opportunities to explore interesting physics (e.g., a multiphase liquid, metastable solid phases, rate-dependent phase transitions, multiple proposed melt lines, etc.). This talk will provide a brief overview of the bismuth studies that have been done using this platform, focusing on recent low-pressure studies that were done to develop this capability. |
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