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Sound speed and thermal property measurements of inert materials: laser spectroscopy and the diamond-anvil cell

Description: An indispensable companion to dynamical physics experimentation, static high-pressure diamond-anvil cell research continues to evolve, with laser diagnostic, as an accurate and versatile experimental deep planetary properties have bootstrapped each other in a process that has produced even higher pressures; consistently improved calibrations of temperature and pressure under static and dynamic conditions; and unprecedented data and understanding of materials, their elasticity, equations of state (EOS), and transport properties under extreme conditions. A collection of recent pressure and/or temperature dependent acoustic and thermal measurements and deduced mechanical properties and EOS data are summarized for a wide range of materials including H2, H2O, H2S, D2S, CO2, CH4, N2O, CH3OH,, SiO2, synthetic lubricants, PMMA, single crystal silicates, and ceramic superconductors. Room P&T sound speed measurements are presented for the first time on single crystals of beta-HMX. New high-pressure and temperature diamond cell designed and pressure calibrant materials are reviewed.
Date: July 1, 1997
Creator: Zaug, J.M.
Partner: UNT Libraries Government Documents Department

The compressibility of cubic white, orthorhombic black and rhombohedral black phosphorus

Description: The effect of pressure on the crystal structure of white phosphorus has been studied up to 22.4 GPa. The {alpha} phase was found to transform into the {alpha}' phase at 0.87 {+-} 0.04 GPa with a volume change of 0.1 {+-} 0.3 cc/mol. A fit of a second order Birch-Murghanan equation to the data gave Vo = 16.94 {+-} 0.08 cc/mol and K{sub o} = 6.7 {+-} 0.5 GPa for the {alpha} phase and Vo = 16.4 {+-} 0.1 cc/mol and K{sub o} = 9.1 {+-} 0.3 GPa for the {alpha}' phase. The {alpha}' phase was found to transform to the A17 phase of black phosphorus at 2.68 {+-} 0.34 GPa and then with increasing pressure to the A7 and then simple cubic phase of black phosphorus. A fit of a second order Birch-Murnaghan equation to our orthorhombic and rhombohedral black phosphorus data gave Vo = 11.43 {+-} 0.02 cc/mol and K{sub o} = 34.7 {+-} 0.5 GPa for the A17 phase and Vo = 9.62 {+-} 0.01 cc/mol and K{sub o} = 65.0 {+-} 0.6 GPa for the A7 phase.
Date: June 5, 2009
Creator: Clark, S & Zaug, J M
Partner: UNT Libraries Government Documents Department

Deflagration Rates and Molecular Bonding Trends of Statically Compressed Secondary Explosives

Description: We discuss our measurements of the chemical reaction propagation rate as a function of pressure. Materials investigated have included CL-20, HMX, TATB, and RDX crystalline powders, LX-04, Comp B, and nitromethane. The anomalous correspondence between crystal structure, including in some instances isostructural phase transitions, on pressure-dependant RPRs of TATB, HMX, Nitromethane, CL-20, and PETN have been elucidated using micro-IR and -Raman spectroscopies. Here we specifically highlight pressure-dependent physicochemical mechanisms affecting the deflagration rate of nitromethane and epsilon-CL-20. We find that pressure induced splitting of symmetric stretch NO{sub 2} vibrations can signal the onset of increasingly more rapid combustion reactions.
Date: March 9, 2010
Creator: Zaug, J M; Foltz, M F & Hart, E
Partner: UNT Libraries Government Documents Department

Final Report. IUT No. B560420 with UC Berkeley. Organic Chemistry at High Pressures &Temperatures

Description: We have successfully completed the research outlined in our proposal: Organic Chemistry at High Pressures and Temperatures. We have experimentally determined a phase diagram which documents the phases and reaction regimes of cyanuric acid , H{sub 3}C{sub 3}N{sub 3}O{sub 3} (1,3,5-triazine-2,4,6-trione), from 300 - 750 K and 0 - 8.1 GPa. We utilized a comparatively new technique to study thin samples of cyanuric acid in the diamond anvil cell in order to collect ambient temperature, high pressure FTIR and Raman data as well as the high-pressure, high-temperature data used in the phase diagram. These experiments made use of the CMLS High-pressure lab's diamond anvil facilities as well as the FTIR and Raman systems.
Date: March 20, 2007
Creator: Montgomery, W; Crowhurst, J C; Zaug, J M & Jeanloz, R
Partner: UNT Libraries Government Documents Department

Photoacoustically Measured Speeds of Sound and the Equation of State of HBO2: On Understanding Detonation with Boron Fuel

Description: Elucidation of geodynamic, geochemical, and shock induced processes is limited by challenges to accurately determine molecular fluid equations of state (EOS). High pressure liquid state reactions of carbon species underlie physiochemical mechanisms such as differentiation of planetary interiors, deep carbon sequestration, propellant deflagration, and shock chemistry. In this proceedings paper we introduce a versatile photoacoustic technique developed to measure accurate and precise speeds of sound (SoS) of high pressure molecular fluids and fluid mixtures. SoS of an intermediate boron oxide, HBO{sub 2} are measured up to 0.5 GPa along the 277 C isotherm. A polarized exponential-6 interatomic potential form, parameterized using our SoS data, enables EOS determinations and corresponding semi-empirical evaluations of >2000 C thermodynamic states including energy release from bororganic formulations. Our thermochemical model propitiously predicts boronated hydrocarbon shock Hugoniot results.
Date: March 9, 2010
Creator: Zaug, J M; Bastea, S; Crowhurst, J; Armstrong, M; Fried, L & Teslich, N
Partner: UNT Libraries Government Documents Department

Elastic constants of B-HMX and tantalum, equations of state of supercritical fluids and fluid mixtures and thermal transport determinations

Description: Ultrasonic sound speed measurements via Impulsive Stimulated Light Scattering (ISLS) were made in single crystals of b-HMX and tantalum over an extended range of temperatures. Elastic constants are consequently determined for b-HMX. Sound speeds are calculated for tantalum, from known elastic constants, and compare favorably with the results presented here. ISLS time-domain fits of tantalum records allowed for thermal diffusion determinations and, correspondingly, thermal conductivity. Measurements of the speed of sound and of the thermal diffusivities of fluid oxygen up to pressures of 13 GPa and at several temperatures are presented. Between 0.1 and 13 GPa the fluid's density increases by a factor of three. Thermal diffusivities rise slowly over this range, and are substantially smaller than those previously measured for the solid b-phase. Additional sound speed measurements were made along the 250 C isotherm in a 1:1 molar ratio mixture of liquid oxygen and nitrogen. These experiments demonstrate the versatility and potential application of a new laboratory within the U. S. DOD and DOE complex. 1
Date: August 21, 1998
Creator: Zaug, J M
Partner: UNT Libraries Government Documents Department

The Melting Curve and High-Pressure Chemistry of Formic Acid to 8 GPa and 600 K

Description: We have determined the melting temperature of formic acid (HCOOH) to 8.5 GPa using infrared absorption spectroscopy, Raman spectroscopy and visual observation of samples in a resistively heated diamond-anvil cell. The experimentally determined melting curve compares favorably with a two-phase thermodynamic model. Decomposition reactions were observed above the melting temperature up to a pressure of 6.5 GPa, where principal products were CO{sub 2}, H{sub 2}O and CO. At pressures above 6.5 GPa, decomposition led to solid-like reaction products. Infrared and Raman spectra of these recovered products indicate that pressure affects the nature of carbon-carbon bonding.
Date: April 13, 2005
Creator: Montgomery, W; Zaug, J M; Howard, W M; Goncharov, A F; Crowhurst, J C & Jeanloz, R
Partner: UNT Libraries Government Documents Department

Shock compression of precompressed deuterium

Description: Here we report quasi-isentropic dynamic compression and thermodynamic characterization of solid, precompressed deuterium over an ultrafast time scale (< 100 ps) and a microscopic length scale (< 1 {micro}m). We further report a fast transition in shock wave compressed solid deuterium that is consistent with the ramp to shock transition, with a time scale of less than 10 ps. These results suggest that high-density dynamic compression of hydrogen may be possible on microscopic length scales.
Date: July 31, 2011
Creator: Armstrong, M R; Crowhurst, J C; Zaug, J M; Bastea, S; Goncharov, A F & Militzer, B
Partner: UNT Libraries Government Documents Department

Pressure-induced isostructural transition in PdN2

Description: We show that a synthesized Pd-N compound crystallize into the pyrite structure by comparison of experimental and calculated Raman intensities. The decreasing Raman intensities with decreasing pressure is explained by a closing of the fundamental band gap. We further discuss the experimental decomposition of this compound at 11 GPa in terms of an isostructural transition within the pyrite structure.
Date: March 5, 2010
Creator: Aberg, D; Erhart, P; Crowhurst, J; Zaug, J M; Goncharov, A F & Sadigh, B
Partner: UNT Libraries Government Documents Department

Energetic Materials and Atomic Force Microscopy: Structure and Kinetics

Description: Understanding the structure and composition of energetic materials at the sub-micron level is imperative for the fundamental studies of hot-spot formation and structural composition of energetic materials. Using in situ high-temperature AFM we have observed the solid-solid phase transition of Octahydro-1,3,5,7,-tetrazocine, HMX, in real time. Massive surface reconstruction occurs during the 1st-order transition. The temperature induced increase in void space and surface roughness observed in the delta phase polymorph of HMX serve to increase the growth rate and volume of shock initiated hot spots and possibly reaction sensitivity. HMX exists in four solid phase polymorphs, labeled {alpha}, {beta}, {chi}, and {delta}. The phase conversion of the {beta} phase to the {delta} phase involves a major disruption of the crystal lattice. The energy required to bring about this change is a measurable quantity. Multiple thermal analysis techniques carried out simultaneously are preferable because the results are directly comparable. Thermal methods are dynamic techniques, where heating or cooling is applied to a sample, unless isothermal conditions are employed. Thermogravimetic Analysis, TGA, can be used to quantify decomposition components in a substance while Differential Thermal Analysis, DTA, can be used to measure the heat flow or the specific heat capacity, with respect to time and temperature. The advantage of TGA/DTA analysis is that the measurement of weight loss and heat flow are taken simultaneously and the observed events are directly related with respect to time and temperature. TGA/DTA experiments were performed to help us take a different look at the chemical nature of HMX and aid us in understanding the void formation process.
Date: July 31, 2002
Creator: Weeks, B.L.; Weese, R.K. & Zaug, J.M.
Partner: UNT Libraries Government Documents Department

Impulsive Stimulated Light Scattering at High Pressure - Precise Determination of Elastic Constants of Opaque Materials

Description: Impulsive stimulated light scattering has been used to measure interfacial wave propagation speeds and elastic constants under conditions of high pressure. Data obtained from single-crystal Ge and Fe, and from polycrystalline Ta is presented. The method is complementary to other techniques for obtaining this type of information. There appears no fundamental reason why it cannot be extended to the 1 Mbar regime.
Date: August 22, 2002
Creator: Crowhurst, J C; Zaug, J M; Abramson, E H; Brown, J M & Ahre, D W
Partner: UNT Libraries Government Documents Department

A study of the elasticity of Ta at high temperature and pressure

Description: The thermodynamic and transport properties of crystals and fluids at high temperature and pressure play a central role in the Earth and planetary sciences as well as in a variety of technologies and constitute a principal probe into the internuclear potential energy function at high density. Observation of surface waves by coherent time-domain optical spectroscopy provides an experimental approach to the determination, in the diamond-anvil high-pressure cell, of the elastic constants and thermal diffusivity of metal crystals as well as the equation of state and thermal transport properties of fluids. The electrical resistivities of metals may also be approximately accessible via the Wiedemann Franz Law. Preliminary results on Ta to pressures of 5.2 GPa are reported here. [Ta, elasticity, sound velocity, thermal diffusivity, equation of state].
Date: August 26, 1998
Creator: Abramson, E H; Brown, J M; Hansen, D W; Ruddle, C M; Slutsky, L J & Zaug, J M
Partner: UNT Libraries Government Documents Department

Experimental EOS and Chemical Studies of High-Pressure Detonation Products and Product Mixtures

Description: We present equation of state results from impulsively stimulated light scattering (ISLS) experiments conducted in diamond anvil cells on pure supercritical fluids, and supercritical fluid mixtures. We have made measurements on fluid H2O (water), CH2O (formaldehyde), and CH3OH (methanol). Sound speeds measured through ISLS have allowed us to refine existing potential models used in the EXP6 detonation product library [Fried, L. E., and Howard, W. M., J. Chem. Phys. 109 (17): 7338-7348 (1998).]. The refined models allow us to more accurately assess the chemical composition at the Chapman-Jouget (C-J) state of common explosives. We predict that water and formaldehyde are present in appreciable quantities at the C-J state of HMX, RDX, and NM. Methanol is predicted to be present only in trace quantities at the C-J state. In the case of methanol, chemical decomposition and phase separation was observed at high temperatures. We are developing micro-FTIR and Raman techniques to determine the chemical composition of the phase separated detonation products.
Date: July 1, 2002
Creator: Zaug, J M; Fried, L E; Crowhurst, J C; Hansen, D W; Howard, W M; Lee, G S et al.
Partner: UNT Libraries Government Documents Department

Quasi-dynamic pressure and temperature

Description: The phase transformation of {beta}-HMX (< 0.5% RDX) to the {delta} phase has been studied for over twenty years and more recently with an optically sensitive second harmonic generation technique. Shock studies of the plastic binder composites of HMX have indicated that the transition is perhaps irreversible, a result that concurs with the static pressure results published by F. Goetz et al. [l] in 1978. However the stability field favors the {beta} polymorph over {delta} as pressure is increased (up to 5.4 GPa) along any sensible isotherm. In this experiment strict control of pressure and temperature is maintained while x-ray and optical diagnostics are applied to monitor the conformational dynamics of HMX. Unlike the temperature induced {beta} -> {delta} transition, the pressure induced is heterogeneous in nature. The room pressure and temperature {delta} -> {beta} transition is not immediate although it seems to occur over tens of hours. Transition points and kinetics are path dependent and so this paper describes our work in progress.
Date: August 26, 1998
Creator: Zaug, J. M.; Blosch, L. L.; Craig, I. M.; Hansen, D. W.; Aracne-Ruddle, C. M. & Shuh, D. K.
Partner: UNT Libraries Government Documents Department

A Beamline for High Pressure Studies at the Advanced Light Source With a Superconducting Bending Magnet as the Source

Description: A new facility for high-pressure diffraction and spectroscopy using diamond anvil high-pressure cells has been built at the Advanced Light Source on Beamline 12.2.2. This beamline benefits from the hard X-radiation generated by a 6 Tesla superconducting bending magnet (superbend). Useful x-ray flux is available between 5 keV and 35 keV. The radiation is transferred from the superbend to the experimental enclosure by the brightness preserving optics of the beamline. These optics are comprised of: a plane parabola collimating mirror (M1), followed by a Kohzu monochromator vessel with a Si(111) crystals (E/{Delta}E {approx} 7000) and a W/B{sub 4}C multilayer (E/{Delta}E {approx} 100), and then a toroidal focusing mirror (M2) with variable focusing distance. The experimental enclosure contains an automated beam positioning system, a set of slits, ion chambers, the sample positioning goniometry and area detectors (CCD or image-plate detector). Future developments aim at the installation of a second end station dedicated for in situ laser-heating on one hand and a dedicated high-pressure single-crystal station, applying both monochromatic as well as polychromatic techniques.
Date: April 21, 2005
Creator: Kunz, M.; MacDowell, A. A.; Caldwell, W. A.; Cambie, D.; Celestre, R. S.; Domning, E. E. et al.
Partner: UNT Libraries Government Documents Department