A5064175708- High-pressure geophysics and materials
- Geological and Geochemical Analysis
- Atomic and Subatomic Physics Research
- Quantum, superfluid, helium dynamics
- Laser-Plasma Interactions and Diagnostics
- Energetic Materials and Combustion
- Boron and Carbon Nanomaterials Research
- Organic and Molecular Conductors Research
- Nuclear Physics and Applications
- Metal and Thin Film Mechanics
- Diamond and Carbon-based Materials Research
- Hydrogen Storage and Materials
- earthquake and tectonic studies
- Nuclear Materials and Properties
- Solid-state spectroscopy and crystallography
- Advanced Chemical Physics Studies
- High-Velocity Impact and Material Behavior
- Catalytic Processes in Materials Science
- Methane Hydrates and Related Phenomena
- Rare-earth and actinide compounds
- Gas Sensing Nanomaterials and Sensors
- Geophysics and Sensor Technology
- Ion-surface interactions and analysis
- X-ray Diffraction in Crystallography
- Transition Metal Oxide Nanomaterials
Sandia National Laboratories California
2021-2024
Sandia National Laboratories
2020-2024
Los Alamos National Laboratory
2022
Nevada National Security Site
2022
Washington State University
2016-2020
Pulsed power accelerators compress electrical energy in space and time to provide versatile experimental platforms for high density inertial confinement fusion science. The 80-TW “Z” pulsed facility at Sandia National Laboratories is the largest device world today. Z discharges up 22 MJ of stored its capacitor banks into a current pulse that rises 100 ns peaks as 30 MA low-inductance cylindrical targets. Considerable progress has been made over past 15 years use precision scientific tool....
Pressure-induced structural and electronic transformations of tungsten disulfide (WS2) have been studied to 60 GPa, in both hydrostatic nonhydrostatic conditions, using four-probe electrical resistance measurements, micro-Raman spectroscopy, synchrotron X-ray diffraction. The results show the evidence for an isostructural phase transition from hexagonal 2Hc 2Ha phase, which accompanies metallization at ∼37 GPa. This occurs displacively over a large pressure range between 15 45 GPa is driven...
Both shock and shockless compression experiments were performed on laser powder bed fusion (LPBF) Ti–5Al–5V–5Mo–3Cr (Ti-5553) to peak compressive stresses near 15 GPa. Experiments the as-built material, containing a purely β (body centered cubic) microstructure, two differing heat treatments resulting in dual phase α (hexagonal close packed) microstructure. The Hugoniot, Hugoniot elastic limit (HEL), spallation strength measured compared wrought Ti-6Al-4V (Ti-64). results indicate LPBF...
Hydrazinium azide (HA) has been investigated at high pressures to 68 GPa using confocal micro-Raman spectroscopy and synchrotron powder x-ray diffraction. The results show that HA undergoes structural phase transitions from solid HA-I HA-II 13 GPa, associated with the strengthening of hydrogen bonding, then N8 40 GPa. transformation recently predicted (N≡N+-N--N=N--N-+N≡N) is evident by emergence new peaks 2384 cm-1, 1665 1165 arising terminal N≡N stretching, central N=N N-N respectively....
The high-pressure response of titanium dioxide (${\mathrm{TiO}}_{2}$) is interest because its numerous industrial applications and structural similarities to silica (${\mathrm{SiO}}_{2}$). We used three platforms---Sandia's Z machine, Omega Laser Facility, density-functional theory-based quantum molecular dynamics (QMD) simulations---to study the equation state (EOS) ${\mathrm{TiO}}_{2}$ at extreme conditions. magnetically accelerated flyer plates Sandia measure Hugoniot up pressures 855...
We report here pressure induced nanocrystal coalescence of ordered lead chalcogenide arrays into one-dimensional (1D) and 2D nanostructures. In particular, atomic crystal phase transitions mesoscale PbS PbSe nanocrystals have been observed monitored in situ respectively by wide- small-angle synchrotron X-ray scattering techniques. At the scale, both underwent reversible structural transformations from cubic to orthorhombic at significantly higher pressures than those for corresponding bulk...
Hydrogen $({\mathrm{H}}_{2})$ and helium (He), the most abundant elements in universe, pose a unique challenge measuring equation of state mixture, owing to their differing physical properties. There remains need for data with high enough precision discriminate between existing (EOS) mix models order understand internal structure gas-giant planets. Here, we have measured EOS precompressed ${\mathrm{H}}_{2}\text{\ensuremath{-}}\mathrm{He}$ mixtures at conditions directly relevant planetary...
MoO3 has large electronic and mechanical anisotropy arising from diverse chemical bonding in its layered structure. Here, we report high-pressure structural transitions to 100 GPa, using confocal micro-Raman spectroscopy, synchrotron X-ray diffraction, electric conductivity measurements at both ambient low temperatures. The results indicate that MoO3-I (Pnma) undergoes a series of phase transitions, initially MoO3-II (P21/m) 11 GPa then MoO3-III (Pmma) 60 GPa. former transition occurs...
The phase diagram of D2S has been investigated to 70 GPa in diamond anvil cells using confocal micro-Raman spectroscopy. results show that molecular IV transforms "polymeric" V at 30 300 K, analogous an extended network structure ice X with symmetrized hydrogen bonds. formation is evident by its characteristic single vibrational Raman peak ∼460 cm–1 for symmetric D–S–D bending/stretching, ∼730 76 GPa. At low temperatures, the proton-disordered more proton-ordered phases IV′ and VI, which...
We report the reversible photochemical transformation of sulfur–hydrogen mixture to (H2S)2H2, which occurs through an expanded state photoactive a-S phase sulfur at 4 GPa. Upon further compression, photoproduct (H2S)2H2 undergoes a transition 17 GPa, and 40 The pressure-induced Raman changes indicate that from I II GPa is associated with proton-ordering process in evident by profound splitting S–H H–H vibrational modes, whereas accompanied disappearance all stretching bending modes partial...
We have studied the compression behavior of ${\mathrm{H}}_{2}\text{\ensuremath{-}}\mathrm{He}$ mixtures in comparison with pure ${\mathrm{H}}_{2}$ and He using powder synchrotron x-ray diffraction, we present pressure-volume (PV) data to 160 GPa. The results indicate that both remain hcp maximum pressure studied, yet they develop a substantial level lattice distortion (100) plane, most profound He-rich solids below 66 measured PV also softening an (or ${\mathrm{H}}_{2}$) -rich upon...
Brillouin scattering spectroscopy has been used to obtain an accurate (1%) $\ensuremath{\rho}\text{\ensuremath{-}}\mathit{P}$ equation of state (EOS) 1:1 and 9:1 ${\mathrm{H}}_{2}\text{\ensuremath{-}}\mathrm{He}$ molar mixtures from 0.5 5.4 GPa at 296 K. Our calculated equations indicate close agreement with the experimental data right freezing pressure hydrogen GPa. The measured velocities agree on average, within 0.5%, ideal mixing model. EOSs presented have a standard deviation under 0.3%...
We have studied the pressure-induced structural and electronic phase transitions in WO3 to 60 GPa using micro-Raman spectroscopy, synchrotron X-ray diffraction, electrical resistivity measurements. The results indicate that undergoes a series of with increasing pressure: triclinic WO3-I initially transforms monoclinic WO3-II (P21/c) at 1 GPa, involving tetrahedral distortion corner-shared octahedral framework, then mixed corner edge-shared seven-coordinated WO3-III 27 large volume change ∼6%...
Pulsed-power generators can produce well-controlled continuous ramp compression of condensed matter for high-pressure equation-of-state studies using the magnetic loading technique. X-ray diffraction (XRD) data from dynamically compressed samples provide direct measurements elastic crystal lattice, onset plastic flow, strength-strain rate dependence, structural phase transitions, and density defects, such as dislocations. Here, we present a cost-effective, compact, pulsed x-ray source XRD on...
Efficient carbon capture requires engineered porous systems that selectively CO
Metal hydrides with a high hydrogen content are important for materials-based storage and high-temperature superconductivity. Nanoconfinement of metal in porous hosts is promising strategy to tune the thermodynamic stability control hydrogen-to-metal ratio. However, lanthanum hydride (LaHx) nanoconfinement materials has been limited due challenges associated isolating stabilizing nanoparticles La or La-hydrides. Here we successfully demonstrated chemical reduction La(III) salts La(0),...
Metal hydrides with a high hydrogen content have long been considered for materials-based storage and but are now attracting attention as potential high-temperature superconductors. 1 Recently, we showed that cryo-milling lanthanum improves diffusion, yielding higher hydrogen-to-metal ratio of hydride up to LaH 4 . 2 Another strategy improving the thermodynamics desorption kinetics metal is nanoconfinement within porous hosts. 3,4 However, this has not previously achieved (LaH x ) due...
The application of pressure, internal or external, transforms molecular solids into nonmolecular extended network with diverse crystal structures and electronic properties, ranging from optically nonlinear CO2–V to high Tc superconducting CS2-III. While these transformations can be understood in terms pressure-induced electron delocalization, the governing mechanisms are complex often result unusual phase/chemical transformation diagrams a large number polymorphs, metastable phases,...
Reaching astrophysically relevant high energy density (HED) material states in the laboratory is an ongoing effort at multiple experimental facilities. We have developed a new dynamic compression platform for Z Pulsed Power Facility that allows sample sizes 100s of μm thickness accommodate grains order to fully capture bulk properties, such as strength. A pair experiments compressed platinum (Pt) HED conditions and conventional inverse Lagrangian analysis well recent Bayesian calibration...
The high-pressure dynamic response of titanium dioxide (TiO2) is not only interest because its numerous industrial applications but also structural similarities to silica (SiO2). We performed plate impact experiments in a two-stage light gas gun, at peak stresses from 64 221 GPa determine the TiO2 along Hugoniot. lower stress experiment shows an elastic behavior followed by elastic–plastic transition, whereas high above show single wave structure. Previous shock studies have shown presence...