A5061542791- Boron and Carbon Nanomaterials Research
- High-pressure geophysics and materials
- Methane Hydrates and Related Phenomena
- Diamond and Carbon-based Materials Research
- Superconductivity in MgB2 and Alloys
- Inorganic Chemistry and Materials
- MXene and MAX Phase Materials
- Metal and Thin Film Mechanics
- Spacecraft and Cryogenic Technologies
- Rare-earth and actinide compounds
- Graphene research and applications
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Inorganic Fluorides and Related Compounds
- Carbon Nanotubes in Composites
- Crystal Structures and Properties
- Advanced Chemical Physics Studies
- Hydrogen Storage and Materials
- Solid-state spectroscopy and crystallography
- Crystallography and molecular interactions
- Advanced ceramic materials synthesis
- CO2 Sequestration and Geologic Interactions
- Semiconductor materials and interfaces
- Perovskite Materials and Applications
- Energetic Materials and Combustion
Carnegie Institution for Science
2016-2025
Elettra-Sincrotrone Trieste S.C.p.A.
2022-2023
Geophysical Laboratory
2011-2020
California Institute of Technology
2017
United States Naval Research Laboratory
2015
Colorado School of Mines
2006-2012
Korea Advanced Institute of Science and Technology
2009
National Geophysical Research Institute
2009
Abstract Highly porous nanostructures with large surface areas are typically employed for electrical double-layer capacitors to improve gravimetric energy storage capacity; however, high area carbon-based electrodes result in poor volumetric capacitance because of the low packing density materials. Here, we demonstrate ultrahigh 521 F cm −3 aqueous electrolytes non-porous carbon microsphere co-doped fluorine and nitrogen synthesized by low-temperature solvothermal route, rivaling expensive...
Inspired by the synthesis of XB3C3 (X = Sr, La) compounds in bipartite sodalite clathrate structure, density functional theory (DFT) calculations are performed on members this family containing up to two different metal atoms. A DFT-chemical pressure analysis systems with X Mg, Ca, Ba reveals that size cation, which can be tuned stabilize B-C framework, is key for their ambient-pressure dynamic stability. High-throughput 105 Pm3̅ symmetry XYB6C6 binary-guest (where X, Y electropositive...
A key challenge in materials discovery is to find high-temperature superconductors. Hydrogen and hydride have long been considered promising displaying conventional phonon-mediated superconductivity. However, the high pressures required stabilize these restricted their application. Here, we present results from high-throughput computation, considering a wide range of high-symmetry ternary hydrides across periodic table at ambient pressure. This large composition space then reduced by...
The hydrogen storage capacity of binary THF−H2 clathrate hydrate has been determined as a function formation pressure, THF composition, and time. amount stored in the stoichiometric increases with pressure exhibits asymptotic (Langmuir) behavior to approximately 1.0 wt % H2. This concentration corresponds one molecule occupying each small 512 cavities large 51264 cavity framework. Contrary previous reports, was not increased upon decreasing below 5.6 mol solution 0.5 %, at constant even...
The compression of glassy carbon forms a series lightweight, ultrastrong, hard, elastic, and conductive carbons.
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTHigh-Pressure Synthesis and Characterization of Incompressible Titanium PernitrideVenkata S. Bhadram*, Duck Young Kim, Timothy A. Strobel*View Author Information Geophysical Laboratory, Carnegie Institution Washington, DC 20015, United States*(T.A.S.) E-mail: [email protected]*(V.S.B.) protected]Cite this: Chem. Mater. 2016, 28, 6, 1616–1620Publication Date (Web):March 7, 2016Publication History Received5 January 2016Revised29 February...
The realization of a novel guest/host carbon-boron sp 3 framework opens the door for new class 3D carbon-based materials.
We predict superconductivity for the carbon--boron clathrate ${\mathrm{SrB}}_{3}{\mathrm{C}}_{3}$ with ${T}_{c}=27\text{--}43\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ Coulomb pseudopotential (${\text{\ensuremath{\mu}}}^{*}$) values between 0.17 and 0.10 using first-principles calculations conventional electron--phonon coupling. Electrical transport measurements, facilitated by an in situ experimental design compatible extreme synthesis conditions ($>3000\phantom{\rule{0.28em}{0ex}}\mathrm{K}$...
We have determined the time-space average filling of hydrogen molecules in a binary tetrahydrofuran (THF)-d8 + D2 sII clathrate hydrate using high resolution neutron diffraction. The lattice THF-d8 occurred upon pressurization. were localized small dodecahedral cavities at 20 K, with nuclear density from approximately spherically distributed and centered cavity. With formation pressure 70 MPa, molecular was found to only singly occupy This result helps explain discrepancies about occupancy...
We report novel molecular compound formation from silane-hydrogen mixtures with intermolecular interactions unprecedented for hydrogen-rich solids. A complex ${\mathrm{H}}_{2}$ vibron spectrum anticorrelated pressure-frequency dependencies and a striking H-D exchange below 10 GPa reveal strong unusual attractive between ${\mathrm{SiH}}_{4}$ bond destabilization at remarkably low pressure. The unique features of the observed ${\mathrm{SiH}}_{4}({\mathrm{H}}_{2}{)}_{2}$ suggest new range...
Raman spectroscopic measurements of simple hydrogen and tetrahydrofuran+hydrogen sII clathrate hydrates have been performed. Both the roton vibron bands illuminate interesting quantum dynamics enclathrated H2 molecules. The complex region spectrum has interpreted by observing change in population these with temperature, measuring absolute content as a function pressure, D2 isotopic substitution. Quadruple occupancy large cavity shows highest vibrational frequency, followed triple double...
X-ray diffraction and Raman spectroscopic measurements confirm that molecular hydrogen can be contained within the small water cavities of a binary sH clathrate hydrate using large guest molecules stabilize cavity. The potential increase in storage could more than 40% when compared with sII hydrates. This work demonstrates stabilization structure previously unknown for encapsulating hydrogen, indicating other inclusion compound materials even greater capabilities.
The interconversion of methane-ethane hydrate from metastable to stable structures was studied using Raman spectroscopy. sI and sII hydrates were synthesized gas mixtures 65% or 93% methane in ethane water, both with without the kinetic inhibitor, poly(N-vinylcaprolactam). observed faster structural conversion rate higher concentration atmosphere can be explained terms differences driving force (difference chemical potential water hydrates) kinetics (mass transfer rearrangement). inhibitor...
Hydrogen sulfide (${\mathrm{H}}_{2}\mathrm{S}$) and hydrogen (${\mathrm{H}}_{2}$) crystallize into a `guest-host' structure at 3.5 GPa and, the initial formation pressure, rotationally disordered component molecules exhibit weak van der Waals-type interactions. With increasing bonding develops strengthens between neighboring ${\mathrm{H}}_{2}\mathrm{S}$ molecules, reflected in pronounced drop S-H vibrational stretching frequency also observed first-principles calculations. At 17 GPa, an...
Abstract It is well known that pressure causes profound changes in the properties of atoms and chemical bonding, leading to formation many unusual materials. Here we systematically explore all stable calcium carbides at pressures from ambient 100 GPa using variable-composition evolutionary structure predictions USPEX code. We find Ca 5 C 2 , C, 3 CaC, CaC have stability fields on phase diagram. Among these, are successfully synthesized for first time via high-pressure experiments with...
Three different sodium-silicon clathrate compounds–Na8Si46 (sI), Na24Si136 (sII), and a new structure, NaSi6–were obtained for the first time using high-pressure techniques. Experimental theoretical results unambiguously indicate that Na-intercalated clathrates are only thermodynamically stable under conditions. The sI can be synthesized directly from elements at pressures 2 to 6 GPa in 900–1100 K range. Over range of conditions studied, sII forms as an intermediate compound prior...
The Group 14 element silicon possesses a complex free-energy landscape with many (local) minima, allowing for the formation of variety unusual structures, some which may be stabilized at ambient conditions. Such exotic allotropes represent significant opportunity to address ever-increasing demand novel materials tailored functionality since these forms are expected exhibit superlative properties including optimized band gaps solar power conversion. application pressure is well-recognized and...
Here we report on the first structural and optical high-pressure investigation of MASnBr3 (MA = [CH3NH3]+) CsSnBr3 halide perovskites. A massive red shift 0.4 eV for 0.2 is observed within 1.3 to 1.5 GPa from absorption spectroscopy, followed by a huge blue 0.3 0.5 eV, respectively. Synchrotron powder diffraction allowed us correlate upturn in properties trend (onset shift) with phase transitions cubic orthorhombic tetragonal monoclinic CsSnBr3. Density functional theory calculations...
BaReH9 is an exceedingly high-hydrogen-content metal hydride that predicted to exhibit interesting behavior under pressure. The high-pressure electronic properties of this material were investigated using diamond-anvil-cell electrical conductivity techniques megabar (100 GPa) pressures. measurements show BeReH9 transforms into a and then superconductor above 100 GPa with maximum transition temperature (Tc) near 7 K. occurrence superconductivity was confirmed by the suppression resistance...
Large-volume, phase-pure synthesis of BC8 silicon ($Ia\overline{3}$, $cI16$) has enabled bulk measurements optical, electronic, and thermal properties. Unlike previous reports that conclude BC8-Si is semimetallic, we demonstrate this phase a direct band gap semiconductor with very small energy moderate carrier concentration mobility at room temperature, based on far- midinfrared optical spectroscopy, temperature-dependent electrical conductivity, Seebeck heat capacity measurements. Samples...