Bulletin of the American Physical Society
2005 APS March Meeting
Monday–Friday, March 21–25, 2005; Los Angeles, CA
Session X4: Extreme Materials Science: the X-Games of Condensed Matter Physics |
Hide Abstracts |
Sponsoring Units: DCMP Chair: Bruce Remington, LLNL Room: LACC 515A |
Friday, March 25, 2005 8:00AM - 8:36AM |
X4.00001: Probing Fundamental Properties of Matter at Extreme Pressures and Densities on the Z Accelerator Invited Speaker: The Sandia Z accelerator has become a unique platform to study matter at extreme conditions. The large currents (20 MA, 200-300 ns rise time) and magnetic fields (several MG) produced by Z generate magnetic compression in the multi-Mbar regime, enabling quasi-isentropic compression experiments (ICE) to several Mbar stresses. Thus, the Z platform is useful in determining high stress material isentropes, performing phase transition studies (including rapid solidification), obtaining constitutive property information, and estimating material strength at high stress. Furthermore, the magnetic pressure can also accelerate macroscopic flyer plates to velocities in excess of 30 km/s. Thus, impact experiments can be performed to ultra-high pressures. Furthermore, the adiabatic release response of materials can be investigated through shock and release experiments, allowing hot, dense liquid states to be probed. The Z platform allows a large expanse of the equation of state surface to be explored enabling new and exciting material dynamics experiments. Specific examples from each of the areas mentioned above will be discussed. [Preview Abstract] |
Friday, March 25, 2005 8:36AM - 9:12AM |
X4.00002: Accessing ultra-high pressures and strain rates in the solid state: An experimental path to extreme materials science on the Omega and NIF lasers Invited Speaker: A new approach to materials science at extreme pressures and strain rates has been developed on the Omega laser, using a ramped plasma piston drive. The laser drives a shock through a solid plastic reservoir that unloads at the rear free surface, expands across a vacuum gap, and stagnates on the metal sample under study. This produces a gently increasing ram pressure, compressing the sample nearly isentropically. The peak pressure on the sample, diagnosed with VISAR measurements, can be varied by adjusting the laser energy and pulse length, gap size, and reservoir density, and obeys a simple scaling relation.$^{1}$ This has been demonstrated at OMEGA at pressures to 200 GPa in Al foils. In an important application, using in-flight x-ray radiography, the material strength of solid-state samples at high pressure can be inferred by measuring the reductions in the growth rates (stabilization) of Rayleigh-Taylor (RT) unstable interfaces. RT instability measurements of solid Al-6061-T6 and vanadium, at pressures of 20-100 GPa and strain rates of 10$^{6}$ to 10$^{8}$ s$^{-1}$, show clear material strength effects. High-pressure experimental designs based on this drive have been developed for the NIF laser, predicting that solid-state samples can be quasi-isentropically driven to pressures an order of magnitude higher than on Omega - accessing new regimes of dense, high-pressure matter. [1] J. Edwards et al., Phys. Rev. Lett., 92, 075002 (2004). [Preview Abstract] |
Friday, March 25, 2005 9:12AM - 9:48AM |
X4.00003: Synchrotron Radiation and High Pressure: New Light on Materials Under Extreme Conditions Invited Speaker: Current technological advances now make it possible to perform experiments on materials subjected to static or sustained conditions up to multimegabar pressures ($>$300 GPa) and from cryogenic temperatures to several thousand degrees ($\sim $0.5 eV range). With these techniques, densities of condensed matter can be increased over an order of magnitude, causing numerous transformations and new physical and chemical phenomena to occur. Growth in this area largely been made possible by accelerating developments in diamond-anvil cell methods coupled with new synchrotron radiation techniques. Significant advances have occurred in x-ray diffraction, spectroscopy, inelastic scattering, radiography, and infrared spectroscopy. With recent developments, structure refinements based on polycrystalline data up to multimegabar pressures have been possible. Single-crystal methods have been extended to megabar pressure, with the prospect of full crystallographic refinements. `Three- dimensional' diffraction data can be collected for determining strength, deformation, and elastic tensors at high P-T conditions. Studies carried out during the past three years provide numerous breakthroughs in high-pressure x-ray spectroscopy and a broad range of inelastic scattering methods. Other experiments have exploited the use of x-ray radiography over a range of pressures. Finally, synchrotron infrared measurements have revealed a wealth of high-pressure phenomena, particularly for molecular systems. Examples to be discussed include investigations of dense hydrogen; transformations in molecular materials; novel ceramics; new types of superconductors, electronic, and magnetic materials; and liquids and amorphous materials. [Preview Abstract] |
Friday, March 25, 2005 9:48AM - 10:24AM |
X4.00004: Frontiers in Electron Microscopy: Probing the Nanoscale in Nanoseconds Invited Speaker: Electron microscopy has traditionally been driven by the desire to investigate the result of a given materials process (e.g. nucleation and growth, fatigue etc) at the highest spatial resolution. However, this type of observation typically gives no indication as to how the material achieved its final state. With the nanotechnology revolution highlighting the novel properties that can be achieved by modifying the processing and ambient conditions a material is subjected to, the need to characterize the fundamentals behind the materials process itself has assumed critical importance. One of the developing methods to achieve this level of characterization is dynamic transmission electron microscopy (DTEM). Using a laser pulse to stimulate the electron emission, pulse durations of nanoseconds and shorter can be achieved with sufficient signal to obtain images and diffraction patterns from materials excited by a laser in a pump-probe configuration (with the probe being the electron beam). A novel nanosecond electron microscope incorporating this principle has been used initially to observe the hexagonal close packed (HCP) to body centered cubic (BCC) martensitic phase transformation in titanium. The general class of martensitic phase transformations occur by a rapid shear of the crystal lattice. No long range diffusion is required during these transformations, thus they propagate through a crystal with a speed that can approach the speed of sound. The images and diffraction patterns obtained can be interpreted in terms of the unusual vibrational stabilization of the high temperature BCC phase of Ti. An interesting observation is that the speed of the transition seems to be dependent on the history of the sample and appears to be linked to the presence of oxygen impurities. \newline\newline This work was performed in collaboration with A. Ziegler, G. H. Campbell, H. Kleinschmidt, and O. Bostonjoglo and supported by LLNL LDRD project 04-ERD-071. This work performed under the auspices of the U.S. Department of Energy by University of California, Lawrence Livermore National Laboratory under Contract W-7405-Eng-48. [Preview Abstract] |
Friday, March 25, 2005 10:24AM - 11:00AM |
X4.00005: Towards the determination of the equation of state of hydrogen and helium at extreme densities: Laser induced shocks on pre-compressed samples. Invited Speaker: The determination of the equation of state of helium and hydrogen at very high density is an important problem at the frontier between condensed matter physics and plasma physics. It is also an important issue in planetary physics for understanding the formation of giant and extrasolar planets. However, the extreme densities relevant to most of the interior of Jupiter are unreachable by either static or single-shock compression techniques alone. Recently, a laser-driven shock-wave in a hydrogen sample, pre-compressed in a diamond anvil cell, has been demonstrated [1]. Consequently, the compression factors of the dynamic and static techniques can now be multiplied. We will present our current effort with the Omega laser at LLE to measure accurately the Hugoniot curves of hydrogen and helium pre-compressed up to 1.5 GPa. The metrology and error bars of the measurements will be discussed. The Hugoniot data points will be compared to published calculations, and an interesting difference in the insulator-metal transition of hydrogen and helium will be discussed. \newline \newline Co-authors are Stephanie Brygoo, CEA, France; Jon Eggert, Peter Celliers, Guilbert Collins, LLNL, Livermore CA 94551 USA; Ryan McWilliam, Raymond Jeanloz, University of California, CA 94720 USA; and Tom Boehly, LLE, New-York 14623 USA. \newline \newline [1] P. Loubeyre et al., High Pressure Research \textbf{24}, 25- 31 (2004). [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