Bulletin of the American Physical Society
19th Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 60, Number 8
Sunday–Friday, June 14–19, 2015; Tampa, Florida
Session J5: Equation of State VII: Multiphase Systems |
Hide Abstracts |
Chair: Brian Jensen, Los Alamos National Laboratory, Amit Samanta, Lawrence Livermore National Laboratory Room: Grand I/J |
Tuesday, June 16, 2015 11:15AM - 11:30AM |
J5.00001: A new equation of state for $\alpha$-quartz Rudolph Magyar, John Carpenter Quartz (SiO$_2$) is often used as an optically transparent window for visar signals in shock experiments and is itself an active component of the experiments. Therefore, the shock response of quartz is an important input that must be known to high fidelity for precise measurement of other materials. We describe on-going work to develop a wide-range equation of state table that includes multiple phases and incorporates the latest high quality experimental and density functional theory (DFT) calculations. The emphasis in this work is the proper description of $\alpha$-quartz along its principal Hugoniot through Stishovite and liquid phases. While molecular dissociation occurs at high pressures and temperatures, we find that an additional dissociation model is unnecessary. Although SiO$_2$ possesses a number of solid phases, we restrict our focus to $\alpha$-quartz and Stishovite as these two provide the density change along the Hugoniot path. We compare the model to recently measured data on Sandia's Z-machine. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE [Preview Abstract] |
Tuesday, June 16, 2015 11:30AM - 11:45AM |
J5.00002: A liquid regime equation of state for silicon dioxide Travis Sjostrom, Scott Crockett A new SESAME liquid phase silicon dioxide equation of state (EOS) has been developed utilizing the best experimental data and theoretical calculations. The EOS inputs include recent alpha-quartz shock Hugoniot results from the Sandia Z machine experiments, as well as quantum molecular dynamics simulations. An immediate and critical application of the new EOS lies in analysis of shock experiments where in recent years alpha-quartz has been used extensively as an impedance match standard at significant (above $\sim$100 Gpa) pressures to measure shock velocities. [Preview Abstract] |
Tuesday, June 16, 2015 11:45AM - 12:00PM |
J5.00003: Equation of State of Dolomite from Shock Hugoniot and Static Compression Studies Dennis Grady Dolomite mineral and dolomite geologies occur naturally in the earth's crust. Interest in the shock equation of state of dolomite rock arose in the 1960's. Reasonably extensive and consistent experimental Hugoniot data from several sources spanning the range of 10~to~170~GPa shock pressure are available for dolomite. In addition, structured shock wave measurements performed in the 1970's provide evidence for a time-dependent phase transformation in dolomite at approximately 20 to 25~GPa shock pressure. Interest in the equation of state of dolomite has resurfaced in response to increasing concerns with the whole earth carbon cycle. In the 2000's and later, three independent investigations of the high-pressure properties of dolomite using DAC methods have identified two solid state phase transitions and new crystal structures in the pressure range of 17 to 37~GPa. The present paper addresses the stark disparities between the earlier shock Hugoniot equation-of-state data for dolomite and the more recent DAC data. [Preview Abstract] |
Tuesday, June 16, 2015 12:00PM - 12:15PM |
J5.00004: Entropy and phase diagram of warm dense water Martin French, Michael Desjarlais, Ronald Redmer Under conditions typical for the interiors of Neptune-like planets, water can occur not only as a fluid phase, but also form superionic states or the solid ices VII and X. Here we employ density functional theory (DFT) in combination with molecular dynamics (MD) simulations to construct thermodynamic potentials for the ices VII and X and for the superionic phases with bcc and fcc oxygen lattices. This allows us to determine boundaries between the phases directly from their thermodynamic functions. In doing so, it is necessary to calculate the entropy from the DFT-MD simulations, which is done with the 2PT-MF method [1] generalized to multi-component systems. In the case of ices VII and X, we develop an analytic expression for the free energy using a multi-stage fitting procedure of DFT-MD data [2]. The respective equation of state agrees well with experiments. The calculated phase boundary between the ices and the superionic phase is consistent with that obtained directly from heating and cooling DFT-MD simulations. \\[4pt] [1] M. P. Desjarlais, Phys. Rev. E 88, 062145 (2013)\\[0pt] [2] M. French, R. Redmer, Phys. Rev. B 91, 014308 (2015) [Preview Abstract] |
Tuesday, June 16, 2015 12:15PM - 12:30PM |
J5.00005: Equation of State of Phenomenological Mechanochemistry of Damage Michael Greenfield Traditional damage theory deals with distributed microcracks rather than with individual cracks. This theory adds just one additional parameter to the set of classical thermodynamic parameters of deformable solids, like strain and temperature. Basically, the traditional damage theory reflects only one experimental observation: the elastic modules become smaller with growing damage. Contrary to the traditional damage theory, the Phenomenological Mechanochemistry of Damage (PMD) includes, in addition to the bulk elastic energy, the energy associated with braking/recovery of chemical bonds. Therefore, in addition to the elasticity equations it includes the equation, describing evolution/dynamics of chemical bonds. Although ``chemical bonds'' is a nano-scale concept, we treat the bonds using phenomenological approach. The additional equation of damage evolution is of the rate type, thus, making the whole model rate-dependent (even in quasi-static approach.) In the paper, we review some earlier results and present the novel ones with emphasis on the rate-dependent effects. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700